Lupinus

For early colour and shape in your garden what could be better than the striking spikes and distinctive foliage of the Lupin.  This versatile plant is ideal to help create a romantic cottage garden or because of its stature, give height and colour to any border.  It can also work well in containers and it is a plant which is very popular with bees. Lupins have gone in and out of fashion through the years and like other plants which produce abundant spires of flowers its lifespan is usually no more than 5 years. But there are many keen nurserymen and women who are constantly striving to produce new breeds of wonderfully coloured vigorous plants to replenish our stocks.

Lupins flower from early to late June onwards and there are approximately 200 species, originating from the Mediterranean, North Africa and the Americas. Amongst the species you find dainty annuals, tall, graceful perennials and a statuesque woody evergreen scented shrub which is the tree lupin.  All species however have long racemes of pea like flowers in shades from white to deep crimson, some of which are bi-coloured.  The easily recognised leaves are green to grey-green or silvery, divided into 5-17 finger like leaflets that diverge from a central point.  The most commonly grown lupins are the Russell hybrids which grow to about 3-4’ high, smaller hybrids can be as small as 1’ tall (L. chamissonis) and tree lupins can grow up to 6’ tall and tend to thrive best in costal gardens.

Lupins are part of the legume family (Papilioniodeae) and like other legumes the roots bear nodules which fix atmospheric nitrogen into the soil and are thus often used as green manure.  And although certain types of Lupin are cultivated for eating (Lupin flour) and as forage and grain legumes for cattle, beware of the seed pods that develop on most domestic plants as they are hazardous if eaten,  they contain toxic alkaloids which causes nausea, vomiting, abdominal pain, dizziness and headaches.

In there natural state Lupins have adapted to the sub-artic climates of Alaska and Iceland, the arid climates of east Africa and Mexico and the sub-tropical parts of South America and the USA.  They have also become a nuisance in New Zealand where they have spread into the wild over vast areas of ungrazed areas and the environment authorities are seeking to reduce their numbers.

History

The name Lupin derives from the latin ‘Lupus’ which means wolf or destroyer.  According to Prof. William Stern in his ‘Dictionary of Plant Names’, this names was given in the erroneous belief that the species destroyed the fertility of the soil, when in actual fact the reverse is the case.

As well as being a popular ornamental plant in gardens, lupins have long been used in agriculture and grown as a food source for more than 2000 years.  Early Egyptian and pre Incan civilisations were known to eat lupins and the Romans grew the annual lupin (probably L. albus) as food for both animals and themselves and also for green manuring.  Even today certain species of ‘sweet’ Lupin are used as crop plants, especially in Europe and Australia for feeding cows and sheep.

The first reference to Lupins in England was by William Turner in 1568 in his book; ‘A New Herbal, parts 1, 2 and 3’ (1551-1568) where he mentions Lupinus albus. From around 1557 L. luteus and L. varians were thought to be cultivated, L. luteus, common name ‘Spanish violet’, was the most popular as it has a very sweet perfume.  The Virginian Lupin, L. perene was introduced to England from North America circa 1637, probably by John Tradescant, (a gardener to Royalty and an early importer of exotic plants) and although grown in the Oxford Botanic Garden it did not become widespread due to its’ poor colour.  The yellow tree lupin (L. arboreus) was also discovered along the Californian cost by Captain Vancouver’s expedition in 1792.

The most important species, L. polyphyllus, which is the ancestor of most of the perennial hybrids, was found and brought to England from North America by the famous plant collector David Douglas (1799-1834). David Douglas who is renown for introducing many species to this country especially the ‘Douglas Fir’ brought this Lupin to England in 1826, before his untimely death in 1834 at the age of 35. L. polyphyllus became very popular and was frequently crossed by English pioneers such as James Kelway in the late 1890’s to develop better and more colourful hybrids.  A fine example of a L. polyphyllus cross was developed by Downer and Harkness in 1917, the red ‘Downers Delight’ and was honnoured by the Royal Horticultural Society in 1918. 

That said, most of the vibrant perennial hybrids that we see today are down to one man; George Russell (1857-1951).  Russell was a gardener from Yorkshire who became fascinated by Lupins, dedicating the latter half of his life to experimenting with crosses and producing a range of cultivars with larger and better blooms in an extensive range of shades; pinks, reds, blues, purples, yellows and numerous bicoloured forms.  George Russell succeeded in creating a dynasty of lupins, the ‘Russell Lupins’ that are still admired and sought after today. 

Propagation

Seeds

Lupin seeds can be grown outside in spring (March-April) and will generally germinate in 5 days or seeds can be sown indoors between sheets of damp paper towels at any time of year.  Seeds can often germinate quicker if the outer shell is nicked slightly and soaked in warm water for 48 hours before sowing. Annual seeds can be planted whilst still wet directly into the growing position.  Seeds should be 2.5 cm (1”) deep and 30-45cm (12-18”) apart. Water well and protect from slug and snail damage.  Perennials and shrubs should be planted in pots or seed trays using seed compost  (50% multipurpose compost plus 50% coarse grit or perlite).

Firm and water compost in pots and sow seeds thinly on top and lightly cover with compost or perlite.  Keep containers undercover, using Perspex, glass or a plastic bag and keep in a warm place out of direct sunlight.  After germination, remove the cover and place in a light spot.  When large enough to handle, prick out the seedlings into individual pots containing multipurpose compost, water regularly and feed once a month.  The plants will be strong enough to place outdoors the following spring/summer, once the cold snaps have passed.

Lupins hybridise easily, mainly pollinated by bees, so seeds collected from a particular coloured species will not produce the same coloured plant as the parent.  The only way to ensure propagation of the same species is by basal cuttings or division.  If you do however, want to collect seeds from your existing plants it is better to take off the top half of the flowers as they begin to die back and leave the bottom half to set seed.  This way you will not exhaust the plant and prolong its life.

Basal cuttings

The best time to take basal cuttings is in spring when the shoots are 15cm (6") high and before the stems become hollow, as hollow stems are less easy to root. Check the base of the plant for shoots and pick medium to thin shoots leaving the thicker sappy shoots to produce flowers for the season. Scrape away some of the soil to reveal the crown and cut the shoots as close to the crown as possible, using a sharp knife.

Trim the base and take off the lower leaves, you can then either use rooting powder or place the shoots directly into a cuttings mix (equal parts multipurpose compost and grit/perlite/vermiculite) and place in a propagator to root. This may take up to a month, following which the new plants can be potted on and planted out in summer. To speed up the process you can put the shoots into a clean jam jar containing 1-2cm (1") of moist, coarse sand/perlite or vermiculite.  Ensure the sand is always damp and place the jam jar in a plastic bag in a warm light position. The cuttings should then root quite quickly.

Division

Lupins have fleshy root crowns and the best way to divide it is; in spring, dig up the plant and separate the woody crowns with a sharp knife ensuring that each new piece has strong roots and several bud growths.  If it is a large old plant, it is better to throw away the centre just keeping the younger, stronger crowns for re-planting.

Cultivation

Lupins are easy to cultivate, generally preferring a lime-free, well drained soil that is not too heavy and a site that is in sun or partial shade. Some of the new strains will even tolerate pollution. Annuals can be sown from seed in spring directly into the ground and will flower the same summer. Hardy herbaceous perennials can be planted in early autumn or spring once the soil is warm enough (usually April onwards).  It is good practice to prepare the ground by adding plenty of organic matter or compost to the soil, but don’t use farmyard manure as this is too strong and will rot the crown.  Dig a hole larger than the rootball and place the plant so that the top of the crown is level with the soil surface, backfill, firm into place and water.  Adding a handful of bonemeal once planted will help with root development. It is essential to protect young plants from slugs and snails, repeated treatment is necessary until the plant becomes more mature and well established.

Care

To make sure your lupins are strong healthy plants add a mulch of well rotted compost or organic matter to the soil around the base every year. This can be done in winter and if your soil is particularly poor you can add a fertiliser in spring such as a liquid seaweed feed.  It is also necessary to prune back the previous years’ growth before the new shoots start to appear in spring.  This can be done in autumn after the flowering season but if you want to give a little bit more protection to the crown leave the dead vegetation on the plant which will help fend off the frost and cut back in spring.

Lupins are particulary prone to slug and snail damage especially the young succulent shoots in spring and so it is vital to use your preferred method of slug and snail control on a regular basis.

They can also suffer from mosaic virus, if any plants have mottling on the leaves lift and destroy immediately to prevent the spread of this disease.

All types of lupin are susceptible to the Lupin Aphid (Macrosiphum albifrons.  This is a large greyish-green aphid (4-5mm long) which originated in North America and made its way to Britain in 1981. It can over winter on basal buds and easily spreads in summer when mature aphids take flight to infest new plants.

This pest has now spread as far as Europe.  The aphids form dense colonies in late spring/early summer (May-July) on the flower stems and the underside of leaves. The aphid is a sap sucking pest which excretes sticky honeydew and a white waxy deposit. The aphid can spread viruses and debilitate the plant, a severe infestation can result in the plant wilting and dying.

There is no non-chemical control apart from regular inspection and removal by hand. None of the normal aphid enemies such as Ladybirds, hoverfly larvae and parasitic wasps are interested in this species.  If you wish to use chemical control, suitable insecticides are Provado Ultimate Bug Killer, Doff All-in-one Garden Pest Killer, Bayer Sprayday Greenfly Killer Plus or Scotts Bug Clear. Organic sprays such as Py Spray Garden Insect Killer, Scotts Nature's Answer Natural Bug Killer or Bayer Organic Pest Control will give limited control but will have to be applied on a more regular basis.

Further Information :

Lupin flour  ‘poses allergy risk’ : The BBC, 8th April 2005.

Lupin flour is used in some baked products.  Research suggests that people who are allergic to peanuts may also be at risk of severe allergy to lupin flour.  Lupin flour is used in some European countries as a replacement for soya in speciality breads and catering foods, some of which are now reaching the UK.

Researchers have suggested that people with peanut allergy - about 1% of the UK population - should avoid any products containing it until they had another allergy test.

For more information click here to read the full BBC article.  

Pearl Lupins as a potential new meat-free protein and cooking oil : The Daily Telegraph 22/11/2001.

Geoffrey Masefield, was a leading specialist in tropical agriculture who carried out research into the prevention and relief of famine.

As a don at Oxford University for some 30 years, he undertook important research into the development of new food crops with a large potential yield. Striking up a correspondence with a German missionary in Peru, Masefield tracked down the vivid blue Pearl Lupin, a little known variety of the lupin flower, cultivated by the South American Indians high up in the Andes. He found that the large seeds of the sturdy flower had a higher protein value than steak and were, moreover, a rich source of edible oil.

The only disadvantage was that the plant in its original state needed to be soaked for two weeks before it was safe to eat. However, through selective breeding, Masefield and his colleagues were able to develop toxin-free Pearl Lupins, which are still being considered as a potential source of meat-free protein and cooking oil.


Where to see Lupins :

The National Collection of Lupins can be seen between late May to mid June at :

Westcountry Nurseries
Donkey Meadow
Woolsery
Devon
EX39 5QH

Tel : 01237 431111

Web : www.westcountrylupins.co.uk