Betty Montgomery: Conifers add color, texture to a winter garden

Plants that are green all year are a key element in landscape design. Walk out of your house now, in the dead of winter, and what stands out in the garden? Trees and shrubs that are green all year give winter interest when deciduous trees have shed their leaves. All evergreens, and conifers, in particular, give the garden color and texture, making the garden more inviting in the winter months.
Conifer, a broad group of plants that are cone-bearer and have needle-like foliage, come in a wide range of sizes, textures and shapes that can give you year-round interest in any setting. Trees and shrubs that fall into this category reproduce by forming a cone instead of a flower. I want to be correct and this can get a little confusing since there is some overlap between conifer and evergreen but a good general statement is “cones versus flowers” for reproduction since there are also deciduous conifers like larch, bald cypress and dawn redwoods, as well as evergreen ones. Reproduction is the key to the difference between evergreens and conifers.
Conifers can be miniature, dwarf, intermediate and quite tall. No matter what size or shape garden you have, there are conifers to fit every need. There is a multitude of choices today that will have different traits. You can find giant conifers and small conifers, small enough to make the perfect focal point for a little container.
Pine, cedar, yew, false cypress, metasequoia and hemlock are the conifers that I have in my garden. There are others like spruce, juniper and fir, but I have not grown them, yet. Some conifers love cooler climates and others like juniper, cypress and cedar can take the heat of the deep South.
Plus, there is wonderful color in conifers and some of them change colors as the seasons change. The many different shades of green that are present in conifers that I find useful in brightening up the garden in the winter. You can also find golden yellow, frosty blue, emerald blue, celadon, silver and cream, and colors in between, plus there are some that are variegated. I have a large deodar cedar named “Blue Ice” that towers above the garden and a golden mop false cypress that weeps close by. “Carolina Blue” cypress with its lacy, blue color adds interest in another area with a pine that has a shimmery silver color glistening in another part of the garden.
If you know the climate where a particular conifer is native, this might help you when choosing a conifer and where to locate it in your garden. If they come from a hot dry area or the cool Northeast, this might tell you something. Conifers are easy to grow and care for, not finicky at all. They survive in full sun, especially if they have blue, silver or dark-green foliage. If they have golden needles, they perform best when planted with morning sun and a little afternoon shade. They are not too picky about soil as long as it drains well. Most conifers prefer slightly acidic conditions but a few will take a more alkaline soil. After a conifer is established there are very few requirements. They are quite drought tolerant once established and you do not have to worry about fertilizing them either.
Pruning is done for both structural and aesthetic reasons. I try to prune my smaller ones but my large trees go unpruned. In general, conifers should be pruned in late winter or early spring to encourage lush, healthy new branches and foliage in the spring.
Since most people, including myself, used to think of conifers as plants for cold climates, and they do take the cold weather of Maine and Colorado, but many will take warmer weather. It was interesting when two Southern airports that I am aware of, decided to go away from planting deciduous trees, to planting conifers. Raleigh-Durham International in North Carolina and Greenville-Spartanburg International have a lush planting of different conifers that perform great in the heat and humidity of the South. I was told they wanted a beautiful landscape and the conifers they chose were more inviting in the winter months rather than having flowering trees that were spectacular when in flower but not so special in other seasons of the year.
With all the attributes that conifers have to offer: being used for color, screens, focal points, hedges, backdrops, a tapestry of color and variety of sizes makes them a group of plants worth learning more about and planting. They fit nicely into informal as well as formal landscapes. There are ones that can be used as ground covers and others that become giant trees. Take an interest in conifers and you too will become a fan of this wonderful group of plants.
Betty Montgomery is a master gardener and author of “Hydrangeas: How To Grow, Cultivate & Enjoy,” and “A Four-Season Southern Garden.” She can be reached at [email protected]

Growing and caring for Conifers

Planting
Spring and early fall, when temperatures are cooler and rainfall more abundant, are the best times to plant conifers. To reduce transpiration or water loss from the tree, plant on an overcast day when there is ample soil moisture. Most conifers grow best in full sun, but a bit of afternoon shade is best for the dwarf conifers in hot southern zones.

  1. Dig a hole twice the width of and more shallow than the height of the root ball. When planting a conifer sold in a container, first loosen the roots by firmly tapping around the pot with the palm of your hand. Then, trim any roots that may be growing out of the drainage holes. Circling roots should carefully be loosened by hand or with a small hand cultivator prior to planting. This will prevent the roots from girdling and eventually killing the plant.
  2. Balled and burlaped conifers are sometimes wrapped in plastic “burlap” or treated burlap, which may be green in color. These coverings do not decompose and should be removed before you fill in the hole with soil. Plants in untreated burlap should be set into the prepared hole, which should then be filled about a third of the way with soil. Next, cut the burlap and cord away from the trunk and roll the burlap back to expose the top of the soil. Finally, you can fill in the rest of the hole, burying the burlap.
  3. Be sure that the trunk flare (where the trunk and roots meet) is slightly higher than the surrounding soil level to compensate for settling, especially if your soil is heavy or poorly drained. Use excess soil to create a saucer or rim around the plant. This will allow water to collect, keeping the plant moist until it is established, and will provide extra soil when settling occurs.
  4. Water thoroughly after planting.

Soil
For most conifers, slightly acid soil that is loamy and well-drained is ideal. Unless the soil is very compacted or so light and porous that it retains very little moisture, you will not need to add organic matter. If soil drainage is a continual problem, consider creating a raised planting bed that has been amended to improve the soil.

Water
Diligent care is critical from the time of planting until new roots are established. For the first few weeks, check the plant every two to three days for signs of stress and water whenever the soil feels dry. Once the roots have grown out into the surrounding soil, which generally takes about three to six months, the plant can be checked less frequently. Established plantings need supplemental water only during periods of prolonged drought. The amount of water will depend on the species and your soil type. On average, water thoroughly if the top two to three inches of soil feel dry. Deep waterings when needed are better than frequent, shallow waterings. It’s important to note that conifers do not show signs of stress as readily as other plants. For example, they seldom wilt; instead, the overall plant color will lighten or fade and interior needles will turn brown.

Fertilizing
Conifers are not heavy feeders and need only an annual application of a general, complete garden fertilizer such as 10-10-10 or 16-8-8, or a top dressing of well-rotted manure. It is best to fertilize in the early spring before the plants break dormancy, or in late fall before the soil freezes.

Pests and Diseases
Bark beetles are the most devastating insects to attack pines. They exist throughout North America in both eastern and western forms. They will kill healthy trees and trees already weakened by other factors. The bark beetles girdle trees while building egg-laying galleries. The lack of sap flow immediately kills the tree, the insects move to adjacent live trees and the damage spreads. The Douglas-fir tussock moth is an important defoliator of true firs and Douglas-fir in Western North America. The larvae feeds on current year’s foliage, causing it to shrivel, turn brown and will kill or top-kill the tree. The pest is considered serious and can kill up to one-third of trees in a stand of Douglas-fir and deform significant numbers of trees remaining alive.

Pitch canker is a recently introduced fungal disease of pines. Monterey and Bishop pines are especially susceptible, although other non-native California pines can become infected. If allowed to progress, pitch canker will kill the tree. The disease was first reported in California in 1986 in the Santa Cruz and southern Alameda county areas. Potential vectors include all twig, cone, and bark beetles associated with Monterey pine. Disease spread can occur through transport of infected trees and tree parts, bark beetle insect vectors, and the use of contaminated tools. Seeds from infected trees can give rise to infected seedlings. Infected seedlings may initially appear disease free, but later develop disease symptoms.

The first symptom usually noticed is color change in the foliage at the ends of branches–these are called “flags.” Flagging can be caused by the disease, feeding activity of twig beetles, or a combination of both. Needles on infected branch tips fade from the normal dark green to lime green, to yellow, and finally to sorrel before needle drop. Needle color change can occur any time of the year. If pitch canker is the cause of the fading, closer inspection of these branch ends will reveal pitch flow at the transition zone between dying and green needles. These characteristics may be hard to see if fading branches are high in the tree. The infected wood under the bark is resin-soaked and amber in color.

The name “pitch canker” is appropriate because infections are characterized by a copious pitchy flow. Cankers may be found on any woody part of the tree including cones, branches, the tree trunk, and exposed, damaged roots. Pitch from large branch or bole infections may run down the trunk for many feet or drip onto the ground. Dried pitch of old infections will be thickened and amber colored. Pitch nodules of the sequoia pitch moth can resemble pitch canker infection. These nodules are usually rounded, but can run down the host for a foot or so. Most have remnants of the insect’s pupal case extending out. Pitch tubes of the red turpentine beetle occur at the base of the trunk. This bark beetle is not believed to participate in disease spread, although attacks can weaken an already stressed Monterey pine.

Pruning and Maintenance
Dead or diseased conifer branches should be removed immediately, regardless of the time of year. Any other pruning should be done when the plant is dormant. Unlike many deciduous shrubs, most conifers can’t re-sprout from older wood, and so a good rule of thumb is never to remove more than one-third of the total growth at a time. If you prune too drastically, the plant may never fully recover. Many of the dwarf varieties never need to be pruned, but do appreciate some thinning to allow air and sunlight to penetrate to the interior of the plant.

The most common method of pruning evergreens is known as “cutting” or “heading” back. Only part of the branch is pruned; the terminal or tip growth is trimmed to side or lateral buds or branches. This promotes thicker, more compact foliage and a smaller overall plant. Pines are pruned in a special way, called candling, to control growth. Candles are the elongated shoots from which the current season’s needles will emerge. To prune a pine, remove one-half to two-thirds of the candle growth in the spring. Gently break the tips off by hand when the needles are just pushing out of the shoot. Do not use pruners as the blades will also cut the tips of the remaining needles, causing them to brown and discolor.

A type of mutation called a reversion is common in dwarf or variegated selections. A reversion is when these cultivars change back to the plant’s “species form.” Cultivars of some species, such as sawara false cypress, are especially prone to reversion. Familiarity with your particular cultivar will enable you to spot—and remove—a renegade branch quickly. To be sure that you have removed the area where the mutation originated, make the cut in the stable growth just below the point where the reversion has occurred.

Mulching conifers is essential. It maintains the relatively cool soil temperatures that most conifers prefer. Mulching also helps conserve water and reduces weed competition. However, the mulch should be no more than two to three inches deep, and should never come in contact with the trunks of your plants.

ADDITIONAL INFORMATION
For more information on conifers, see the website for the American Conifer Society at www.conifersociety.org or The Gymnosperm Database at www.conifers.org.

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Growing and Caring for Conifers

Conifers are woody plants, which means that they have stems and trunks of wood, which are covered with bark. They have woody stems even if they are ground covers or tiny miniatures that grow a fraction of an inch a year. Most of us think of trees when we hear ‘woody plants’ but there are thousands of shrubs, groundcovers and vines that are included in the category. Growing and caring for conifers and other woody plants is generally the same.

Woody plants need water, nutrients and sunlight, just as herbaceous plants do (herbaceous refers to soft, green stems). However, they have particular requirements regarding soil type and root treatment, as well as sometimes needing staking. Pruning is also more complex than with herbaceous plants and is done for both structural and aesthetic reasons.

Growing and Caring for Conifers: Selecting

Conifers in boxes for sale at Rare Tree Nursery in Silverton, Oregon

When you are shopping for conifers, and this holds true for woody plants in general, you need to pay attention to structure, roots and overall health. Woody plants grow more slowly than perennials and it is important to evaluate them using ‘tree time’, understanding that problems are slow to develop but also slow to correct. When you evaluate a conifer for purchase, take note of the following:

It’s best to buy conifers and other woody plants from knowledgeable nursery owners. Webeditor Sara Malone shopping at Pond and Garden in Cotati, CA, a retail nursery specializing in dwarf conifers

  • Is the color true to its intended description? For example, a golden conifer that’s supposed to be deep green indicates a lack of nutrients.
  • Is it structurally sound, e.g. if it is a plant that is supposed to have a excurrent, ‘Christmas tree’ shape, does it? Is there evidence of awkward branching? Will it stand without staking?
  • Do you see girdling roots at the crown? This could create problems going forward.
  • How deeply buried is the root flare? It’s critical for a conifer’s root flare (the point at which the roots begin to “flare out” from the trunk) to be visible at the soil surface. Many woody plants are buried far too deeply. The plant must be ‘excavated’ so that the flare is visible. You may remove any small, adventitious roots that have filled the soil above the flare. This is one of the biggest problems with nursery stock.
  • If possible, pop the plant out of its pot. Is it excessively root-bound? How much ‘root management’ will be necessary? With rootbound plants it is important to tease apart (sometimes cut apart) the roots.

Woody plants are grown in one of two ways: in containers or the field. Container-grown plants are much more likely to be root-bound than those that are field grown, however their entire ‘history’ is evident in the container, and it is relatively easy to get a look at the roots. They are grown in a potting medium that is generally very fast draining, but should be removed as much as possible before planting. Field grown plants are exactly that: they are grown in fields in the grower’s native soil, then root-pruned, excavated and the root ball wrapped and tied in burlap, and often referred to as balled-and-burlapped (B&B).

B&B conifers have an unique set of issues:

  • The soil is often clay, and the clay ball often buries the root flare.
  • There is often much more root trauma involved with digging and preparing these trees, which means more transplant shock and a greater need for supplemental irrigation.

Adventitious roots grow into the soil above the flare. It is safe to remove them

Growing and Caring for Conifers: Placing

  • It is always helpful to know the climate where your conifer is native. Consider the amount of heat, sun, wind, drainage and rain that a plant receives in its native habitat, and try to replicate this as best you are able. Some conifers that are native to very difficult environments are adaptable to easier conditions, such as mugo pines. Others are much fussier. You will learn from other conifer collectors, or, even better, from experience!
  • Conifers with blue, silver, or dark-green foliage look and perform their best when planted in full sun.
  • Most golden conifers look and perform best when they receive morning sun and some afternoon shade. Some of the golden cultivars will burn in full sun until established, which can take 2-3 summers. A few never burn in full sun. Check the plant description to be sure, or better yet, consult with other conifer lovers in your area.
  • Conifers with white variegation tolerate very little to any direct sun. However, in deep shade, the variegation will often be suppressed. Bright light but never direct sun is the “sweet spot” here.
  • Some species naturally grow in the understory of large canopy trees. These do quite well in places of low light. Chamaecyparis, Taxus and Tsuga are the best conifer species for shady locations.
  • Remember to consider growth rate when placing your conifer; fast growing selections will need space to expand.

Growing and Caring for Conifers: Preparing for Planting

  • Dig a hole no more than the depth of the pot / root ball and twice as wide. If your soil is poorly-draining, consider planting your conifer in a slightly raised position, and mounding better-draining soil around it. DO NOT amend the planting hole itself; you will be creating a ‘bathtub’ that will fill with water.
  • Do not add organic amendments of any kind to the soil. In nature, woody plants live in un-amended soil. You can use pebbles or other inorganic materials to increase drainage in the mound, if necessary.
  • Remove any excess soil above the root flare, then loosen the roots, especially roots that wind around the inside of the pot and especially girdling roots near the trunk. If you cannot untwist the girdling root(s), cut it off at the origin.
  • Spread the roots outward into the hold in a radiating manner.
  • Back-fill, ensuring that the root crown is visible.
  • Stake if necessary, taking care to remove any stakes that were used in the pot, and inserting a new stake or stakes at the outer edge of the rootball and tying loosely.
  • Fertilizers and transplant tonics are not necessary and can do more harm that good. They promote excessive top growth before roots develop.
  • Mulch around the root ball, taking care to keep mulch away from the trunk. Mulch will help keep roots cool in summer, warm in winter, and help retain water and retard weed growth.

Growing and Caring for Conifers: Watering and Staking

  • Thoroughly water your new conifer upon planting. This ensures proper contact between roots and soil.
  • For the first few years in the ground, water when the soil is dry to the touch 1 to 2 inches below the surface.
  • After 3 to 5 years, little to any supplemental water is necessary provided you live in a climate that receives natural rain during the growing season. If you live in a summer-dry climate, additional irrigation is generally necessary.
  • Once planted, a stake may be necessary if the plant is tall, wobbly in the hole and you live in a windy area.
  • A stake should be in place for only as much time as is necessary to allow sufficient development of the root system to hold the plant upright. Trees, particularly, need to flex and move in order to develop trunk strength, and long-term, tightly bound staking prevents this from happening.

Ongoing Care

As noted, conifers rarely need fertilizing and do not need or benefit from additions of organic matter. Do not overwater, and check and adjust/remove any staking in the first year or two. Diseases and pests are generally genus and location-specific; some genera have very few problems, others, such as hemlocks (Tsuga) are rapidly being diminished by a specific pest, this case the wooly adelgid. Refer to information about your specific plant and learn about pests and diseases prevalent in your area.

We will discuss pruning in a separate entry.

Enjoy your conifers and don’t hesitate to call on ACS members for suggestions or feedback!

ACS Member Holly Reid after a successful shopping trip at Peacock Horticultural Nursery in Sebastopol, CA

What Are Conifers: Growing Conifers In The Garden Landscape

Perhaps one of the best reasons to plant conifers in the garden is that they require very little care. They rarely need fertilizer, resist most insects and diseases, and only need to be watered during prolonged dry spells. Pruning is optional. You can prune them to limit their height and some conifer tree types can be clipped into fanciful topiary art, but they grow into lovely trees and shrubs with or without the occasional trim. Let’s learn more about growing conifers in the garden landscape.

What are Conifers?

Conifers are trees with sharp, needle-like foliage that remains on the branches year round with only a few exceptions. Bald cypresses and larches are notable exceptions that drop their needles in winter. Conifers get their name from the cones which serve as reproductive structures. A few species have berry-like structures instead of cones.

The female cones have ovaries on the individual scales which are pollinated by the windblown pollen from the male cone. The female cones mature into large, woody structures that drop to the ground in autumn. The male cones are quite small in comparison to the female structures, and often go unnoticed.

Coniferous Plant Info

A conifer tree list includes:

  • Pine
  • Spruce
  • Cedar
  • Fir
  • Juniper
  • Cypress
  • Arborvitae

Within these groups you’ll find thousands of species and cultivars, each with its own characteristics.

When choosing a conifer for your property, its best to consult with a local nurseryman. Choosing from a conifer tree list for your U.S. Department of Agriculture plant hardiness zone only tells you that the tree will withstand the minimum temperatures in your area. There is much more to consider when choosing a tree that will last for many years to come.

We appreciate conifer tree types most in winter when their green foliage, sometimes tinged with blue, gold and gray provide color just when we need it most. Some types also produce brightly colored winter berries. When planted in the right place, a conifer can protect homes and gardens from icy winter winds and drifting snow.

A conifer’s dense foliage can also act as a screen, blocking out unsightly views and providing you with privacy. For the ultimate in privacy, choose types that have branches that extend all the way to the ground. The canopy of a conifer tree also provides year-round shade.

Tips & Tricks

Apart from larix conifers need good drainage. There are more conifer casualties from overwatering and water logging than hot summers. Plants have a habit of being able to close down in hot or dry weather and can come back to life when moisture arrives. In long prolonged spells of dry weather water a little and/or cover with a piece of shade netting. Good drainage is achieved by mixing a few chippings or stones with the existing soil but do not plant in boggy or solid clay situations.

You get better yellows if planted in full sun and better blues in partial shade.

Conifers do not need much fertilizer and a light dressing of fish, blood and bone worked into the soil around the plants will be quite adequate.

Pots and troughs should be planted with a mixture of ericaceous compost and soil 50/50 with a little gravel, or drainage sand and of course drainage holes in the base. Top off with stones, gravel, bark as all these items retain the moisture in the pot or trough for the summer months. Lift a stone in your garden and you will find it is always a little damp underneath!

To keep miniatures very small try planting them in their arrival pot into your pot or tough and sinking just below ground level to hide the original pot. This restricts the root growth but the plant can still grow out of the drainage holes. In effect you are semi-bonsai-ing the plant. If you eventually want the move the plant it can be transferred to a larger pot or new site with less disturbance of the roots.

Conifers will grow quite happily in gravel or stoney sites. Abies koreana which are usually grown for their lovely blue cones, will cone much earlier and more profusely if grown in stoney and rough ground than lush fertilized situations.

All conifers can be trimmed to suit your needs. Let them establish for a couple of years and trim in autumn or early spring to shapes you prefer. A much more bushy plant can be obtained by cutting out leading shoots and allowing the side shoots to fill the plant in.

Pests – Vine Weevil are a naturally occurring pest and in particular like Taxus varieties. The adult weevil eats pieces from the leaves and lays its eggs in the soil around the plant which grow into white larvae which feed on the roots. A chemical if now available from garden centre shops to water on the soil to resolve the problem.

Growing & Planting Out Conifers

It’s been a busy week for us, not least because we’ve had the builders in. Where the house roof meets the wall of the old cowshed there’s a gully that channels the water to the gutter. Well it should channel the water away but the lead was cracked so the water pushed down into the wall where it oozed through making the house damp.

I’d tried to repair it with waterproof paint but it hadn’t worked so time for the professionals. Rendering was chiselled off the wall, slates removed from the roof and the old, very patched lead flashing replaced before re-rendering and slating. Not a cheap job but it had to be done. Hopefully a dryer winter this year than last indoors at least.

Moved from 7.5cm pot on left to 1ltr pot on right

I’ve been planting out some conifers. Initially when we moved I thought to plant just native trees but conifers being evergreen look better in winter so we’re planting a few around. Never be afraid to change plans when facts hit you on the noggin.

The cost of trees is closely related to how old they are, obviously cheaper to care for a plant for one year rather than two or even four. So we buy small plants, pot them on and eventually plant them in the ground when they’re big enough to survive all that gets thrown at them. Happily they don’t seem to appeal to the blessed sheep that seem to be our biggest (in every sense) garden pest.

Conifers tend to like a fairly acid soil so when I get them in their little 7.5cm pots, I move them into 1 litre pots with a mixture of half ericaceous and half normal multi-purpose compost to which I add about a third of normal soil (that’s quite acidic here) and a little slow release fertiliser.

Conifer in Final Pot where it’s been for 2 years now

The next year I double the pot size and increase the ratio of normal soil to about half the mix. Depending how fast growing, they’ll either go to a larger pot or for their final pampered year into large tubs. In the tubs I put a layer of old turf upside down which acts as a water holding sponge.

In the summer we liquid feed the conifers about half what we’d feed the flowers in tubs, preferably with an ericaceous feed.

When planting out, I dig a hole about twice as wide as the pot and half as deep again. Break up the base of the hole with a fork and add some compost along with 500gr of bonemeal to feed it for the next few years.

Take some of the soil removed from the hole and mix with compost about 50:50 in the wheelbarrow. Remove the tree from the pot and tease the circling roots out a little. Making sure the top of the pot soil is level with the ground, back fill from the barrow adding a little slow release shrub fertiliser to the soil.

Tread down well as you fill and then give a really good watering, at least one can full if not two, to settle everything down. In dry weather, water weekly to really get them established.

Conifer finally planted out and hopefully growing on

If you were to just grow the conifers on in compost rather than mixing some soil in, then they’d probably grow a little faster but when they go into the ‘wild’ the tree will check as the roots won’t be used to soil and have been known to just keep circling the original root ball. Sticking with the good stuff.

Given a few years, they should be getting towards 2M high and providing some winter greenery to look at. Do watch what variety you get and remember fast growing usually means a large tree. I’m trying to add some decoration, not a tall forest so I’m looking for trees with a maximum height of three metres, two is fine but not the really dwarf types.

Rowan (Mountain Ash) Trees

The next project I’m thinking about is to grow a bulk amount, maybe 50, Rowan in pots. Rowans do fairly well here but we’ve had much better results with pot-grown trees about 4 years old rather than bare-rooted 2 year olds. But the 4 year old trees can easily run over £20.00.

The local trees are heavy with berries but I believe extracting the seeds from them is a fiddly job and 100 seeds can be purchased for a few pounds which would be reasonable for the time saving.

Choosing a conifer, when and where to plant

Choosing the right conifer for your garden

  • Finding the right conifer for the right place is key.
  • Consider the eventual height and spread of different varieties very carefully. Taller growing varieties won’t just stop growing when they reach a sensible height.
  • If you’re looking to plant fast-growing varieties and want to control their height, make sure you can definitely commit to pruning at least once a year. If you’re looking to choose a tall-growing variety make sure you can commit to clipping it at least once per year.

Planting a conifer near Jackson’s Nurseries, Staffordshire

  • Limit your selection to dwarf conifers for rockeries. Anything larger will end up requiring you to lift the stones to remove it at a later date. Rockery conifers combine well with shrubs like Daphne and miniature bulbs. Their foliage offers year-round colour, texture and form.
  • Juniper Blue Carpet makes a great choice for ground cover on slopes whilst common yew (Taxus baccata) is a great alternative to box for formal hedges.
  • Growing conifers in containers can be a great way to control excessive growth in smaller gardens.

Juniper Blue Carpet is a great choice for groundcover

When to Plant

  • Conifers grown in containers can be planted at any time of the year, providing the ground is not frozen or waterlogged and it’s not excessively windy. If you have the choice, early autumn planting works best for most conifers so their roots can establish whilst the soil is still warm, leaving them best equipped to cope with the winter cold and grow strongly in spring.
  • Frost-proof conifers such as Cedrus deodara ‘Feelin’ Blue’ are best planted in early spring.
  • Root ball conifers can be planted from the beginning of October to mid-April.
  • If you’re not able to plant immediately, leave your conifers in a cool, light, frost-free place, out of the sun. Containerised conifers can be left in their pots. If they’re at risk of drying out, dunk in a bucket of water.

If you can’t plant immediately, leave your conifer in a cool, light, frost-free place

Where to Plant

  • Aspect. Most conifers grow best in full sun, but a bit of afternoon shade is best for dwarf conifers in warmer southern parts of the UK.
  • Shelter. Choose a sheltered location – avoid planting in areas exposed to cold winds as the foliage will get scorched and turn brown.
  • Soil Type. Conifers prefer an acidic soil, ideally a loam that’s well-drained. If you have a heavy or poor soil, consider incorporating some ericaceous compost or organic matter such as well-rotted pine needles into the planting hole. If drainage is a problem, a raised bed can work well.

Fertilizing

A fertilization program is used to maintain trees and shrubs in a vigorous condition and to increase their resistance to injury from diseases and insects. However, the addition of any soil nutrient is recommended only if soil or plant foliage tests indicate a deficiency. Trees and shrubs that need fertilization to stimulate more robust and vigorous growth include those exhibiting pale green, undersized leaves and reduced growth rates and those in declining condition (e.g. dead branch tips, dieback) resulting from insect attacks or disease problems. Trees and shrubs which should not be fertilized include newly planted specimens and those with severe root damage from recent trenching or construction. The root systems of these plants will need to re-establish before fertilizers are applied. Older, established trees do not need to be fertilized every year.

For trees and shrubs in northern Illinois, the two most common causes of nutrient problems are high pH (alkaline) soils, which can lead to chronic deficiencies of nutrients in some tree species, such as red maple and pin oak, and nitrogen-deficient soils. Nitrogen (N), phosphorus (P), and potassium (K) are essential plant nutrients and these are most commonly applied. A list of soil testing services is available.

HOW AND WHEN TO FERTILIZE

Fertilizers are labeled to indicate proportions of available nutrients. For example, a label showing a 20-5-5 formulation indicates 20% nitrogen (N), 5% phosphorus (P) as phosphoric acid, and 5% potassium (K) as potash. Thus, a 50 pound bag of 20% nitrogen fertilizer contains 10 pounds of actual nitrogen (50 x .20 = 10).

The following general recommendations apply to trees and shrubs needing a fertilization program. Soil and foliage test results may indicate more specific nutrient requirements.

For all trees and shrubs:

If needed, the best time to fertilize is late April or early May, or late fall once plants are dormant. The recommended fertilizer should be spread evenly across the soil surface. The amount of actual nitrogen applied should be 3 pounds (lbs) per 1,000 square feet. Do not use fertilizer containing herbicides, such as those formulated for use on lawns. The nitrogen content of the fertilizer should be 12% to 30%, with phosphorus and potassium at 3% to 12%. Fertilizer application rates are based upon the area occupied by the roots. Roots spread well beyond the branches on established trees and shrubs; therefore, the area beneath the plant to be fertilized should be 1.5 times the diameter of the branch spread. For groups of plants, estimate the surface area underneath the entire planting to be fertilized.

The Proper Time to Prune

An important aspect of pruning is knowing when to prune plants. Proper timing helps to insure attractive, healthy, productive plants. The proper time to prune various woody plants in the yard and garden are indicated below.

Deciduous Shrubs

Many deciduous shrubs are planted in the home landscape for their attractive flowers. Spring-flowering shrubs bloom in the spring on the growth of the previous season. Two widely planted examples are the lilac and forsythia. The proper time to prune spring-flowering shrubs is largely determined by their condition and the amount of pruning required.

Old, neglected spring-flowering shrubs often require extensive pruning to rejuvenate or renew the plants. The best time to rejuvenate large, overgrown shrubs is late winter or early spring (mid-February to early April) before the plants begin to leaf out. While heavy pruning in late winter or early spring will reduce or eliminate the flower display for a few years, the restoration of a healthy, vigorous shrub is more important.

If spring-flowering shrubs need only light pruning, prune them immediately after blooming. Pruning immediately after bloom allows the gardener to enjoy the spring flower display and gives the shrubs adequate time to initiate new flower buds for next season.

Summer-flowering shrubs, such as potentilla and Japanese spirea, bloom in summer on the current year’s growth. Prune these shrubs in late winter or early spring. Summer-flowering shrubs pruned from mid-February to early April will still bloom in summer.

Many deciduous shrubs don’t produce attractive flowers. These shrubs may possess attractive bark, fruit, or fall leaf color. Prune these shrubs in late winter or early spring.

Don’t prune deciduous shrubs in late summer. Pruning shrubs in August or early September may encourage a late flush of growth. This new growth may not harden sufficiently before the arrival of cold weather and be susceptible to winter injury.

Evergreen Shrubs

Prune evergreen shrubs, such as juniper and yew, in late March or early April before new growth begins. Light pruning may also be done in late June or early July. Avoid pruning evergreen shrubs in the fall. Fall pruned evergreens are more susceptible to winter injury.

Deciduous Trees

The best time to prune deciduous trees is late winter or early spring (February, March, and early April) before they begin to leaf out. Some trees, such as maples, “bleed” heavily when pruned in late winter or early spring. However, the heavy bleeding doesn’t harm the trees. The trees won’t bleed to death and the flow of sap will gradually slow and stop.

To prevent the spread of oak wilt, avoid pruning oaks from April 1 to July 1. Pruning oaks during this period may attract sap beetles carrying the oak wilt fungus to the pruning cuts and transmit the disease to healthy trees. An excellent time to prune oaks is February and March.

If possible, avoid pruning deciduous trees in the spring as they are leafing out. At this time, the tree’s energy reserves are low and the bark “slips” or tears easily. Another poor time to prune is during leaf drop in the fall.

Evergreen Trees

An excellent time to prune spruce and fir is late winter when they are still dormant. Spruce and fir possess side or lateral buds. The pruning cut should be just above a side bud or branch. Pines are pruned in early June to early July when the new growth is in the “candle” stage. Pinching or snapping off one-half to two-thirds of the candle reduces the pine’s annual growth.

Unwanted lower branches on all evergreen trees can be removed in late winter.

Fruit Trees

The best time to prune fruit trees is late February to early April. Fruit trees pruned in fall or early winter may be susceptible to winter injury.

Grapes

Prune grapevines in March or early April. Grapevines pruned at this time of year will bleed heavily. However, the bleeding will not harm the vines.

Roses

The upper portions of modern roses, such as hybrid teas, floribundas, and grandifloras, typically winterkill due to exposure to low winter temperatures and extreme temperature changes. Gardeners should prune out the dead wood after the winter protection is removed from modern roses in late March to mid-April.

Old garden roses, hybrid rugosas, and other hardy roses often survive Iowa’s winters with little or no winter injury. Those that bloom only once a year should be pruned immediately after flowering. Those that bloom throughout the summer should be pruned in March or early April.

Clematis

Clematis varieties are often placed into groups based on their flowering characteristics. Some varieties bloom in June and July on the current season’s growth. Others bloom on stems from the previous season’s growth and again in late summer on new wood. Despite these differences in flowering characteristics, pruning practices for the types commonly grown in Iowa are basically the same. Simply wait until growth begins in early spring and then prune out all the dead wood.

This article originally appeared in the February 11, 2000 issue, pp. 9-10.

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