Plug plants and how to care for them

Plug plants are an excellent and economic way to fill your garden with summer colour with the minimum of fuss.

Seeds are cheaper to buy, but sowing and growing them successfully usually involves purchasing propagation equipment and germination can be hit and miss and pricking out tiny seedlings is a fussy job. Buying plug plants gives gardeners the luxury of leaving the professional grower to take care of the trickier early stages and to step in once the young plants are a little more established and then grow them, each in their own plug of compost, until they are ready to be potted up or planted into their final positions.

How much work you need to do with plug plants and the price you pay for them depends on how big they are when you buy them. The smaller they are, the lower the price – but the more TLC they’ll need.

    • Mini plugs are the first of the season, filling garden centres and nurseries from late February. These need the most attention and time to grow on in trays or pots. They will need to be transplanted and grown on a windowsill, or in a greenhouse or conservatory, before planting out ready to flower.
    • Standard plugs come next and require potting and growing on for a month or so if you want filler plants for beds and containers.
    • Garden-ready plug plants are usually healthy, well-established plants in pots and can be planted straight out into their final position in the garden, though these may also benefit from being grown on for a few weeks in a large pot, for sturdier roots.
Caring for plug plants

Potting on
Plug plants should be potted on into larger pots or trays as soon as possible after you have purchased them.

Water your plants so they are just moist. The best way to do this is to place them in a container of water and allow them to soak it up from the roots.

Fill a small pot or seed tray with good quality, free draining multipurpose compost and make a hole in the centre, roughly the same size as the plug plant· Gently pinch the bottom of the plug and push up from the bottom gently holding it by the leaves. Place the root ball in the hole ensuring the stem is at the same level in the compost as it was before and firm the compost lightly around the plug.

Gently water the freshly potted plants and allow any excess to drain away. Place them somewhere well lit, ventilated and reasonably warm such as a greenhouse or windowsill. After 2 – 3 weeks feed them with a balanced liquid feed and repeat every 10 to 14 days.

Hardening off and Planting out
Once your plants are sturdy and well grown, you can harden them off ready for planting outdoors. This just means acclimatising them to lower outdoor temperatures for a week or two by putting them outside in a sheltered spot during the day and bringing them back in at night. If temperatures drop below 5°C keep them inside until the colder weather is over.
When the plants are well rooted into the compost, and the risk of frost has passed, your plugs should be ready for planting out into their final position. Water them well 1-2 hours before planting out, and again when in position. Once in the ground, water regularly, especially in dry sunny spells.

Henry Street Garden Centre has a large range of mini plug plants now in store as well as the full complement of composts and fertilisers.

What are Plug Plants?

Our Guarantee

We go out of our way to ensure that your plants arrive in perfect condition. If not we will refund or replace immediately. No quibble.

How to grow plug plants

  • Open Packaging Immediately on Receipt
  • Place the plants somewhere reasonably warm. If you have a greenhouse, around 16-18°C is the best temperature. Alternatively, a kitchen windowsill is a suitable place.
  • Allow the plants to settle and acclimatize for 2-3 hours.
  • Water your plants with clean tap water. The best way to do this is to place them in water for a few minutes and allow them to soak it up. A saucer or dish should suffice, alternatively the opened out transport packaging makes a handy container.
  • Transplant your plugs on the day you receive them if you can. Use a good quality, free draining multipurpose compost. 13cm pots (5”) are the best size to use. If you are using old pots, make sure you sterilise them first to remove any pathogens. We find Jeys Fluid to be the best, if you can’t find any, give them a good wash with warm water and soap.
  • Fill your pots with compost up to about 1cm below the rim. Don’t compact the compost in the pot. Make a hole in the centre roughly the same size as the plug plant. Handle the plant gently by the leaves or root ball place in the hole, minimising compost compaction below the plug. Try to make sure the surface of the plug is not buried Firm lightly around the plug.
  • Gently water-in your newly potted plants, with clean water and a fine rose, label your plants.
  • Grow on your plants in a fairly warm area such as a kitchen windowsill or greenhouse.
  • Start feeding your plants around 3 weeks after planting with a general feed.
  • Plant out your plants into their final growing position according to the instructions received with your plants. Enjoy!

Plug plants – how do you grow them on?

It’s your last chance to buy plug plants, the baby plants which start off at around half the size – and half the cost – of the regular 9cm pot plants you buy later on in the season to fill containers.

They’re usually available until the end of April, but as the weather’s been cold this spring, the season is running three to four weeks later, which means there’s extra time to bag your bargain babies, says Tim Evans, horticultural buyer at Wyevale Garden Centres.

Savings can be great, says Evans. “A 9cm-pot patio plant in a garden centre will range from £2 to £2.50, whereas the current plug price for a 4.6cm pot is about £1.30, or you can get cheaper multi-buys,” he says.

Plug plants can be planted into hanging baskets (Thompson & Morgan/PA)

“You’ve probably also got the widest range of plants available from young plant suppliers at this time of year, which gives you greater flexibility to create your own mixes.

“And your finished product will be first to flower – and should last through the season if you feed and deadhead it regularly.”

Easier than growing from seed

Begonias can be tricky to grow from seed (Thinkstock/PA)

While packets of seeds may be cheaper to buy, some plants are tricky or take a long time to grow from seed, including begonias, petunias, geraniums and dianthus, according to award-winning online garden retailer Thompson & Morgan.

What should you look for when buying plug plants?

Plug plants should have a healthy root system (Thompson & Morgan/PA)

The most important thing to look out for is a healthy root system, advises Thompson & Morgan. Evans adds: “Avoid plug plants which are stretched and straggly. You want something which is compact, a good shape and hasn’t gone yellow, which may mean they’ve run out of food, haven’t had enough light or have been too cold.”

Do you need a greenhouse?

“Not everyone has a cold greenhouse, so a lot of people pot plug plants into 9cm or 10cm pot and carry on growing them on the windowsill,” notes Evans.

Plants like peppers can be grown on a windowsill (Thinkstock/PA)

Once the plant has filled the larger pot in a few weeks’ time, it should be ready to be planted into its final place outside, but don’t do this until the end of May or beginning of June, when all risk of frost has passed.

What do you do when you get them home?

Whether you buy them online or in store, remove them from their protective packaging and water them. Ease out the plants and the soil in which they growing all in one go by pushing up from underneath the container using your thumb or, if the plugs are very small, a pencil, so you avoid damaging the fragile stems or leaves.

Plant them on in larger pots as soon as you receive them and place them in in bright, frost free conditions under cover but out of direct sunlight. Before planting in their final spot outdoors, harden them off in a sheltered spot outside for seven to 10 days to acclimatise the plants.

Remove bacopa carefully (Thompson & Morgan/PA)

What type of potting compost should you use to pot them on?

“Any good multi-purpose compost should be sufficient. Pot them on as soon as you can to get them established,” says Evans. “A lot of the plugs already have little roots sticking out of them and establish quickly once they are re-potted in a larger container.”

Don’t add feed at the initial stage of repotting, he advises. However, if you’re using plug plants for a hanging basket which you are planting up now and keeping in a cool greenhouse until the weather warms up, feel free to use a multi-purpose compost incorporating slow-release fertiliser, to help sustain the plants through the summer.

You can plant plugs straight into containers

Some retailers sell garden-ready plug plants (Thompson & Morgan/PA)

If you have the space under cover, give your summer bedding a head start by planting your plugs into their final containers, but keep them in a sheltered frost-free place until the weather warms up.

Some garden retailers sell tough, large garden-ready plug plants which have already been hardened off and are ready to plant out when you receive them.

But if you have smaller plug plants that you are housing in an unheated greenhouse and the weather turns really cold, you may need to cover them with horticultural fleece at night to protect them.

What types of plants are available as plugs?

Geraniums are a good choice of plug plant (Thinkstock/PA)

They are usually annuals, ranging from geraniums and bacopa to busy Lizzies, ageratums and fuchsias. You can buy perennial plugs from some online retailers as well as vegetables, including tomatoes, chillies and sweet peppers, and small pots of strawberries.

Are some plug plants better than others?

Fuchsias are available as plugs (Thinkstock/PA)

Cutting-raised plants tend to be more robust, says Evans: “Their ultimate garden performance is generally better than seed-raised varieties. Some plug plants don’t exist as seed-raised, such as fuchsias, bacopa and bidens.”

General Care

Your plants have been grown under ideal conditions, and inspected by one of our experts prior to careful packaging and despatch by post. However, should they have been damaged or delayed during delivery, please contact us immediately.

To achieve that stunning summer long display, please ensure that you regularly check your plants to ensure that they have adequate water, and feed regularly. When planting containers, mix a slow release plant food such as Suttons Controlled Release Fertiliser, plus some Water Storing Crystals into the compost. They will then need less attention throughout the summer. Watering below the foliage canopy of the plants will reduce marking and damage to the flowers. Removing the dead and damaged flower heads will not only improve the appearance of the plants, but will also prevent the plant putting energy into seed production and ensure that more flowers are produced.

Tip! – Remember to ensure all summer bedding plants are protected from spring frosts. Do not plant outdoors before late May/early June.

On delivery of your plants do this straight away:

  • Carefully unpack your plants and check that the compost is moist.
  • Should any of the compost be dry, water carefully using a small watering can, and allow to drain.
  • Stand in a light, warm place, and then follow the growing on instructions in this leaflet as soon as you can – provided they are kept moist, they can usually be left for up to 3 days.


  • To reduce the need for weeding once you have planted out your bedding display, you can dig over your planting area a couple of weeks before you intend to plant. As the soil warms this will encourage the weed seeds to germinate and these can be removed before you plant up your display.
  • If you intend to plant ‘Value Plug Plants’ through the side of your baskets then you can use a smaller pot than 7cm and transfer into baskets when well established.

Extra Value Plug Plants (Plant Size: approx. 5cm)

  • A 7cm pot filled loosely with moist compost is ideal to plant these sturdy young plants into. In each pack of extra value plug plants you will find a dibber stick.
  • Gently push it through the base hole of each cell and ease the plant and root plug out of the tray, placing it into the centre of the filled pot until the roots of the plug are covered.
  • Firm the compost gently around the base of the plug whilst ensuring the stem and leaves remain above the top layer.
  • Alternatively, plant into trays of compost. A 36x22cm (14×8½”) tray will hold up to 24 plants.
  • Grow on in a light place at a temperature of 16 ̊C (60 ̊F).
  • For Begonia and Impatiens 18 ̊C (65 ̊F) would be even better to encourage quick establishment.

Value Plug Plants (Plant Size: approx. 7cm)

  • These larger cell grown plug plants will develop very quickly once planted in 7 to 9cm pots.
  • Ease them from their tray using the dibber stick provided, pushing through the base hole of each cell, then plant into the centre of the pot ensuring all the roots are covered but that the stem and leaves remain exposed.
  • Alternatively, plant into trays of compost.
  • Begonias and Impatiens should ideally be grown on at a minimum temperature of 18 ̊C (65 ̊F).
  • For other plants 16 ̊C (60 ̊F) would be suitable.

Garden Ready Plug Plants (Plant Size: approx. up to 9cm)

  • Always ensure that the risk of frost has passed before you plant these into the garden.
  • Should there still be a risk in your area then we suggest that you pot these plug plants into a 7 to 9cm pot and allow them to develop further somewhere warm and light, before planting, rather than leave them in the growing tray.
  • For planting directly into the garden, ensure that the soil has been dug over and lumps broken down, then plant straight into their flowering position.
  • In areas where the existing soil is poor, incorporate a good handful of compost into each area you are planting.
  • Once planted don’t forget to give your plants a drink and protect them from any slugs and snails that may appear.

Super Plug Plants (Plant Size: up to 12cm)

  • We have selected these plants to be grown where you would like something that bit different in areas such as hanging baskets, patio containers, tubs and raised beds.
  • For best performance we recommend that you grow them on further, either in 9 to 11cm pots or in the final planting containers, maintaining a minimum temperature of 13-16 ̊C (55-60 ̊F).
  • Allowing these plants to establish in this way before placing in their final position outdoors will pay dividends later in the season.

Perennial Pot Ready Plug Plants (Plant Size: up to 12cm)

  • Pot these plants individually into 10-12cm (4-5”) pots using a good quality potting compost and grow on in a greenhouse, frame or outdoors once the risk of frost has passed.
  • When the plants have been potted for approximately 4-6 weeks apply a balanced liquid fertilizer every 7-10 days.
  • Once the perennial plants are fully established and have produced a good root system they can be planted into their flowering position.
  • Ensure that the soil you are planting into is well drained, incorporating a general purpose fertiliser when planting.
  • Plants should be watered directly after planting and during dry spells.

Potted Plants (Plant Size: up to 20cm)

  • These are large potted plants for ultimate convenience!
  • Well established plants in various pot sizes (as detailed against each plant) that can be planted straight into their final positions


  • For small bulb varieties up to 5+cm in size, plant up to 5cm (2″) below the soil level, for larger bulbs over 5+cm in size plant 10cm (4″) below the soil level.

Please note: Our Extra Value and Value plug plants trays contain extra cells over and above the stated quantity – so that you should normally receive a few extra plants, even if some of the cells are empty.

How to grow your plants

Whether your plants are delivered as bareroots, bulbs or plugs, you can follow our step by step guides to get your plants off to the best possible start.

If you would like to know more about our product specifications, view our How we grow and send your plants information page.

For more specific growing instructions please visit the individual product pages.

Growing Plug Plants

Open your plug plants immediately on arrival. For the best start they should be potted up as soon as possible. Pot them up into individual pots using a good quality potting compost and water them thoroughly. Grow them on in bright frost free conditions until they are large enough to plant outdoors. Prior to planting out in the garden, your plants should be acclimatised to outdoor conditions in a sheltered spot over 7 – 10 days.

Growing Bulbs and Tubers

If your bulbs and tubers can’t be planted immediately, open the packaging and store them in a cool, dry, frost free place until planting becomes possible. You can plant bulbs in containers or directly into the ground. However, Begonia tubers will always need to be started off in pots indoors. Most bulbs and tubers will enjoy a fertile, well drained soil. The recommended planting depth will vary between species; but as a rule of thumb most bulbs can be planted at 3 times their own depth. Cyclamen and Begonias are exceptions to this rule and should be planted just at the soil surface. Water sparingly after planting.

Growing Potted Shrubs and Perennials

Our potted plants can be transplanted into larger pots and grown on, or planted out in their final positions. Prior to planting in the garden, you will need to acclimatise them to outdoor conditions in a sheltered spot over a period of 7 to 10 days. Prepare a planting hole wide enough to accommodate the rootball and deep enough to ensure that the soil of the potted plant sits at ground level. Gently firm the plant into the ground leaving a slight depression around the plant – this will help to direct water towards the roots. Water your plant well to settle the soil.

Growing Bareroot Perennials

If your bareroot perennials can’t be planted immediately, open the the packaging and store them in a cool, frost free place. If the delay in planting will be longer than a week then bareroots should be potted up and grown on in a cold frame, greenhouse or sheltered spot outdoors for planting out at a later date. Prepare a planting hole wide enough to accommodate the roots when they are spread out, and deep enough that the crown of the plant is just a few cm below soil level. Backfill the hole with soil and firm the plant in gently. Iris rhizomes are the exception to this rule and should be planted so that the rhizomes sit at ground level.

Growing Bareroot Trees and Shrubs

If your bareroot trees and shrubs can’t be planted immediately, remove the packaging and store them in a cool, frost free place. Before planting, soak the roots in tepid water for a couple of hours to rehydrate them. Prepare a planting hole that is wide enough to accommodate the roots when they are fully spread out. A soil mark is often visible on the stem, indicating the original planting depth at the nursery. Plant your tree or shrub so that this mark sits at soil level. If this is not obvious, then plant it so that the top of the root system sits just below ground level. Firm the soil around the roots and water well.

Selecting the Right Cell Tray

What propagation tray is best for you?

There are many different size cell trays to choose from. If you want to get started propagating your seedlings you need to figure out which cell tray is best for your needs. We will go over the different options to help you select which is best for you.

32 Cell Trays

32 Cell trays are the largest cell trays that we carry. Each cell is 2″ x 2″ giving your seedlings plenty of room to grow. Each cell has a removable insert for easy transplantation. They are great for plants that are more prone to transplant shock such as cucumbers, melons, squash and pumpkins. These cell trays will encourage faster growth as there is more access to nutrients and plenty of space.

Recommended Plants: Early season Tomatoes, Flowers, Cucumbers, Melons, Squash, Pumpkin and Other Vine Crops.

72 Cell Trays

72 Cell trays are the most popular choice. They are a good balance between space for growing and seedlings per tray. Each cell is 1.5″ square and 2.25″ deep which makes them a great option for a large variety of plants. These are also a good choice for the vine plants, however you will want to transplant the vine plants earlier than you would with the 32 Cell trays.

Recommended Plants: Early Season Peppers, Early Season Vine Crops, Early Season Cole Crops (Cabbage, Cauliflower, Collards, Kale, Mustard, Kohlrabi, Broccoli, Brussels sprout, Watercress)

128 Cell Trays

128 Cell Trays are a great choice if you have many plants that you wish to grow while they are still small seedlings. Each cell is 1″ square and 2.25″ deep. You will be able to plant 78% more seedling with 1 tray than the more common 72 Cell.

200 Cell Trays

200 Cell Trays are an excellent tray if you want to be economical about growing Cole Crops and Lettuce. You will be able to grow ~2.8 times as many plants with one tray as you would with a 72 cell tray. Each cell is 0.75″ square and 2.25″ deep. However you will need to transplant your seedlings at an earlier stage.

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