What Is A Potato Bush: Information About The Blue Potato Bush Plant

The potato bush plant is an attractive shrub that grows up to 6 feet tall and wide. It is evergreen in warm climates, and its dense growth habit makes it suitable for use as a hedge or screen. You can also grow it as a tree by removing the lower branches. Pinching the tips of new growth encourages bushiness.

What is a Potato Bush?

The potato bush plant (Lycianthes rantonnetii), a native of Argentina and Paraguay, is best suited to the frost-free climates found in U.S. Department of Agriculture plant hardiness zones 10 and higher. A member of the Solanum family, it is closely related to potatoes, tomatoes and eggplants, but you should never eat it because it is poisonous. Common names for this plant include blue potato bush, Paraguay nightshade and blue solanum shrub.

Potato bush plant is grown outdoors in warm climates. In areas with cool winters, grow it as a potted plant that can be brought indoors when frost threatens. In cool areas, an abundance of small, blue flowers bloom in summer and fall. In frost-free areas, it blooms year round. The flowers are followed by bright red berries.

Potato Bush Growing Conditions

Blue potato bush needs a sunny location and a frost-free climate. The plant prefers an organically rich soil that is constantly moist, but well-drained. Achieve the right balance of moisture by watering the plant slowly and deeply when the surface feels dry. Apply a layer of mulch over the soil to slow water evaporation. If the soil drains too quickly, work in some organic material, such as compost.

Potato bushes grow best if fertilized regularly. You can use a 2-inch layer of compost once or twice a year; a complete, balanced, slow-release fertilizer in spring and late summer; or a liquid fertilizer once every month or two. Compost helps the soil manage water efficiently.

Avoid growing a blue potato bush in areas where children play, as they may be tempted to put the bright red berries in their mouths.


Not to be confused with : Duck-Potato

Some similarities to : Tomato but that has yellow petalled flowers which are narrower and cut deeper than those of Pototo.

The flower has superficial resemblance to those of: Aqualegia (Columbine which are also purple, droop downwards, and have five pointed petals, but otherwise the plant is totally different.

Uniquely identifiable characteristics

Distinguishing Feature :

Potatoes are grown as the main staple diet for folk in the UK. According to the BBC Radio program ‘Farming Today’, potatoes are the third most important staple crop in the World (although it was not made clear if this is by nutritional value, by weight of crop, or by area planted or whether by some other unknown criteria). Locally it is grown in Ireland, Lancashire and Cheshire as well as other areas such as Lincolnshire. The flowers have five petals and five yellow stamens that generally congregate as one to protrude rudely from the centre of the flower. The petals are either white or pale purple, but other varieties exist with pink, red and blue petals. There are two basic types that are commonly cultivated; those with pinkish skins, and those with white skins. The potatoes with white skins tend to have white petalled flowers, whereas those with pinkish skins tend to have flowers with coloured petals. There are many other types of Potato, including Purple Potato, which seems to be extinct in the UK. When left to grow without being harvested, the flowers will produce small green poisonous tomato-like fruits which contain up to 300 seeds. Potatoes can be grown from these seeds, or vegetatively by re-planting sprouting tubers. Paradoxically, so-called ‘seed-potatoes’ are tubers intended to be planted for vegetative propagation!

Just recently a potato has been bred with a deep beetroot or purple coloured tuber called ‘Purple Majesty’, which is sold by a well known UK supermarket. The deep purple coloration is throughout the bulk of the tuber, not just on the surface. There are about 5000 other varieties of potato in the World, many non-white.

The potato has been bred so as to minimise the poisonous alkaloids within the tubers called collectively Solanines, but this is not necessarily so for any other part of the plant such as the leaves, stems or flowers or berries, which still tend to be deadly poisonous. (No one eats potato leaves as salad!).

However, the edible tubers (called ‘potatoes’) do contain residual amounts of solanines, with a particularly high concentration in and around any sprouting parts, which is why any sprouting shoots should always be removed before cooking. If the tubers, once lifted from the ground, are exposed to light or sunlight, they will turn green on the exposed side. The green is just chlorophyll, but wherever any green parts form, the solanine concentration around that area soars very high, making them particularly poisonous. Any green parts of potatoes should be removed before cooking. Although some insubstantial proportion of the solanine content is destroyed on cooking, much still remains. Eating green potatoes kills! Potatoes are, after all, a member of the Nightshade Family, which includes Deadly Nightshade.

The potato plant produces tubers on its extensive roots as an energy store for the coming winter months when photosynthesis is at a minimum. The tubers are almost wholly carbohydrates; starch, which is not a single compound, but a mixture of polysaccharides; polymerised amylose sugar units (glycosides).

Potato is one of the few plants capable of converting the inorganic chloride ion (as found, for example, in common salt, NaCl) into organic chlorine. Other plants capable of this are Yellow Star-Thistle, Common Valerian and many plants in the Pea Family (Fabaceae)). Potatoes can release small amounts of Methyl Chloride CH3Cl, gas (an organocloride) into the atmosphere after harvesting, providing it had access to a source of inorganic chloride, which most do. (These are quite separate from the organochlorine residues found in plants as a result of organochloride pesticides sprayed onto them). See Organochlorides in plants on the Chameleon page.


The glycoalkaloid poisons α-solanine and α-chaconine are to be found in the nightshade family of plants, the (Solanaceae), in particular in potatoes (Solanum tuberosum), tomatoes (Solanum lycopersicum or Lycopersicon esculentum), egg plant (aubergines) (Solanum melongena), Sweet and hot peppers (Capsicum species) Thorn-Apple (Datura stramonium), Apple-of-Peru (Nicandra physalodes), Black Nightshade (Solanum nigrum) and Bittersweet (Solanum dulcamara). It is present in small quantities throughout potato tubers, especially in the sprouting shoots, but a lot more is synthesized by the potato if the tuber is exposed to sunlight, where the exposed parts become green (with harmless chlorophyll). It is in and near the green parts where the highest concentration of solanine is to be found. Solanine is not rendered safe by boiling, much still remains, but deep frying at 170 Celsius does destroy most of the solanine. Normally, potatoes contain poisonous solanines at concentrations between 20mg and 150mg per kilogram of raw potato, but when turned green on exposure to sunlight may contain as much as 1000mg/kg, mostly just under the skin (the shoots contain even higher amounts). Solanine adds an un-pleasant bitterness to the flavour of potatoes when its concentration exceeds 200mg/kg, so potato poisoning is now rare, especially as cooks are now more aware of the dangers of greening or sprouting potatoes.

Solanine has, amongst many other effects, a choline esterase inhibitor function and thus affects the central nervous system. The symptoms of solanine poisoning are nausea, vomiting, diarrhoea, stomach cramps, burning of the throat, heart arrhythmia, dizziness, and in severe cases hallucinations, loss of feeling, paralysis, jaundice, hypothermia and death. It causes apoptosis in cells; the cells commit suicide. Ingested concentrations of solanines of between 2mg and 5mg per kilogram of body weight will cause severe poisoning, possibly fatal.


Demissidine, as a glycoalkaloid with glycosides attached , is found in significant concentrations in the skins of un-ripe potatoes. It is reported to inhibit the enzyme cholinesterase and is also a suspected teratogenic substance, inducing gross abnormalities and birth defects in newborns (such as two heads). It modifies DNA. It has been shown to have anti-bacterial properties, such as activity against Staphylococcus aureus, the bacteria responsible for MRSA. In comparison to the solanines above, Demissidine lacks the double bond in the steroid entity, and also a methyl group on the piperidine group (top right).


Calystegines are poly-hydroxylated nortropane alkaloids, derived from Tropane but without the methyl group on the nitrogen atom. These two are found in potatoes, Tomatoes, Sweet and Chili Peppers, Eggplants, Sweet Potatoes, Mulberries and Cabbage and are potent glycosidase inhibitors. They were first reported in plants of the Bindweed Family (Convolulaceae) but are most ubiquitous in the Nightshade Family (Solanaceae). The major proportion of these alkaloids are synthesized within the roots, and the largest increase in production was observed in tubers that have suppressed sucrose synthase activity. Increases in calystegines seems to be linked with sucrose availability.

Calystegines are not destroyed by cooking and are stable enough to be found in processed potato products such as dried mash potato. Storage of potato tubers at 5°C increases the 4-O-α-D-galactoside of Calystegine B2 and Calystegine A3.

The inhibition of mammalian β-glucosidase and α-galactoside activities raises the possibility of toxicity in humans when large quantities of these plants are consumed.

Other Calystegines are to be found within Apple-of-Peru, Danish Scurvygrass and other plants.

Solanum crispum
“Chilean Potato Bush”

If you think of potato vine as kind of a ho-hum plant then prepare to have your eyes opened by this exceptionally pretty, purple-flowering relative. Growing as a scandent bush, this vigorous variety dons one inch, star-shaped, intense lilac blooms eventually smother the vining shrub, making for quite a summer and fall spectacle. Yellow centers provide an attractive contrast. Elliptical green leaves provide a verdant backdrop, allowing the purple flowers to really pop. Very small berries (poisonous!), which progress from green to golden and finally purple, appear in the autumn. Just as tough as its familiar cousin, though it definitely wants to be in some sun, once established it needs little water. It tops out at 15-20’ but can be kept more compact if desired. This native of Chile and Peru can be grown as a relaxed, stand-alone shrub or trained on a fence or trellis. It can even be grown in a large container, as an ornamental or espallied as a privacy screen. Plant in neutral to alkaline soil in a sunny location. Deer-proof but watch out for aphids and gray leaf mold. Prune back hard in late spring to flush out new growth. Attracts bees.

Curious Plantsman

Potato Vine, botanically known as Solanum jasminoides or Solanum laxum, is a fast growing and easy to care for evergreen vine. If the clusters of white flowers look familiar that’s because this plant is in the Nightshade family alongside potatoes and tomatoes. Here in Santa Barbara it flowers all year long with the heaviest bloom being in the Spring – it gets covered in white. It grows very densely and the new growth tendrils out like the snakes on Medusa’s head – crazy wild!

This is my neighbor’s Potato Vine (which you’ll see in the video below) growing on a 4′ high fence – a pruner’s delight!

I have one of these vines growing on my side fence which I keep pruned to a very small scale. It looks very different than my neighbor’s. In my years as a professional gardener I maintained quite a few of these. Here’s are a few other things you need to know about this plant if you have one or plan to buy one:

*This vine grows to 25′.

* It needs full or part sun.

*Water it regularly when establishing. After that, it’s fairly drought tolerant.

* The best time to give it a major prune is after the major bloom (late Spring). Here it can be nipped all year long because we rarely get a freeze.

*Pay attention to how big it gets & how fast it grows. It is best planted on a tall,long fence or large arbor. My neighbor planted 4 plants on a low, short expanse of fence which is major overkill. I know we all want instant gratification but those 1 gallon plants grow like beanstalks!

* It can take a range of environmental conditions but does need a means of support and needs training.

* It’s not fussy as to fertilizer. Amend with a good organic compost when planting and then apply more once a year. As with most plants, it likes good drainage.

* It’s hardy to 20-25 degrees.

This is a dense growing plant. Some of that new growth grows back on the old growth. That’s why a few prunes a year are recommended to keep it from becoming the man eating vine it wants to be.

The Potato Vine foliage is very fresh in appearance and the plant has an overall lacy feel. So you can see this is not a small scale vine but it is a very popular landscape plant because of its almost non-top profusion of white starry flower clusters and easy care. Relatively easy care that is – all I can say is that if you get this plant, then you’d better like pruning!

Here I am up close & personal with my neighbor’s Potato Vine:

Do you like vines? Here are some links to some other beautiful vine options:

Red Trumpet Vine

Bougainvillea Tips and Facts

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