Hostas

HostasWoodland gardens and shaded areas have been covered in several Growing Today articles over the past year or so. While most of the articles have mentioned hostas, few have considered just how useful, versatile and economical they really are.Almost all country gardens are bordered with trees, either as shelter belts or small woodlands, and that is where hostas really come into their own. They are ideal for filling in under trees and their ease of propagation enables a large collection to be built up quite quickly from relatively few parent plants.Many of the plants described as woodlanders — Astilbe, candelabra primroses, Rodgersia, etc. — would perhaps be more accurately described as semi-bog plants, but hostas are truly at home when grown under trees, even if the soil is dry. Such large-leaved plants look as if they would demand huge amounts of water, and true enough, they do look better if well-watered, but they can handle quite long periods of drought provided they are shaded from the hottest sun. Although this may seem unusual at first glance, it’s only to be expected of plants that have to compete with the roots of large, thirsty trees.Hostas are principally native to Japan and temperate parts of China. There they share their woodland habitat with a great variety of companion plants, many of which are widely cultivated. But whereas Pachysandra, Sarcococca, Hemerocallis, Ruscus and the like are frequently promoted for dryish woodlands, hostas are usually thought of as plants for moist areas, often very moist areas such as around ponds or the border of bogs.I must admit that I have promoted this view too. It was not that I hadn’t been told or read that hostas were very tough, rather that their succulent appearance seemed to belie such ideas. However, observations over recent months have caused me to see the error of my ways.Several years ago I planted out about 150 hostas in a large open bed in a nursery display garden. Trees planted at the same time were intended to eventually shade the hostas. Well, the trees haven’t done all that well, while the hostas have thrived. They now form a dense carpet of widely varied foliage and they flower better with more light — hostas have stems of small lily-like, usually lavender, flowers, sometimes lightly scented, that are attractive though often overlooked.Granted, without shade the foliage, especially that of the variegated forms, is smaller and inclined to dry around the edges. Also the leaves die off earlier in the autumn, but when you consider that these plants are rarely watered and are exposed to the full heat of the summer sun, they perform remarkably well. As the trees gradually become established, they can only do better.I have seen similar plantings in public gardens under large, established trees. The additional light really lifts the foliage, which is large and brightly coloured, even though the soil looks fairly dry and such large trees must extract most of its nutrients and moisture.The thing that finally convinced me that hostas are not bog plants was an article that I read by a gardener from New Mexico. We would probably consider hostas to be totally unsuited to such a hot, dry climate, but this gardener made the observation that where most of the traditional hosta companions, such as astilbes, failed, hostas thrived. He joked that he was contemplating planting them with cacti just for the shock value.Hosta varietiesThe beauty of hostas lies in their foliage. The Japanese use the leaves as a salad vegetable but we are more enamoured with the enormous range of foliage colour and form rather than the culinary value. Colours range from the intense blue of the sieboldiana and fortunei forms through bright grass green to the soft yellow-green of ‘Lemon Lime’, ‘Gold Drop’ and similar cultivars. Not forgetting, of course, the numerous variegated cultivars that can contain any shade of green, cream and yellow. Leaf size ranges from almost grass-like through to heart-shaped leaves over 40 cm wide.In recent years hostas have enjoyed a huge increase in popularity to the extent that a careful search of the nursery catalogues reveals that well in excess of 100 cultivars are available. As with other plants that rely primarily on foliage for effect, there is inevitably a fair degree of similarity and duplication among the cultivars. Also, this similarity makes the classification and identification of hostas the stuff of nightmares.Nurseries are not immune from this confusion — plants are frequently mixed up or misnamed — so make sure you choose your hostas when in leaf in order to be reasonably sure of what you are getting. For the same reasons they can be risky candidates for mail order.Hostas are plants that demand to be experimented with: shift them around and see where they do best and how they blend with other plants. It’s very difficult to tell exactly how a small hosta in a nursery pot will perform in your garden. It really is a case of try it and see. While I can find merit in most of the common cultivars, my favourites tend to be those with very bold and distinctive foliage. For starters consider:Hosta fortunei ‘Hyacinthina’ — often sold as Hosta glauca. 35 cm × 20 cm blue-green leaves with a puckered “seersucker” effect. The flowers are pale lavender. Hosta tokudama is similar.Hosta sieboldiana — 35 cm × 30 cm blue-green puckered leaves. The flowers are white to very pale lavender. Not to be confused with the narrow-leaved H. sieboldii.‘Sum and Substance’ — sieboldiana-like 30 cm × 25 cm foliage is golden-yellow with a heavy texture and is very enduring.‘Blue Wedgewood’ — has smooth blue-green foliage. It should appeal to those that find the sieboldiana hostas too cabbage-like.‘Halcyon’ — 20 cm × 12 cm smooth, blue-green leaves. Showy bright lavender flowers.‘Krossa Regal’ — I think this is the best of the blue-green hostas. Raised by American enthusiast Guy Krossa, this cultivar has lush, brightly coloured 25 cm × 20 cm foliage with the bonus of attractive light pink flowers.‘Lemon Lime’ — this is a small cultivar. The 20 cm × 15 cm foliage is quite yellow when new but greens as it matures. It tolerates a wide range of conditions.‘Gold Drop’ — 15 cm × 15 cm leaves. Just a small plant but very brightly coloured and holds its golden yellow colour through the season.‘Thomas Hogg’ — often sold as H. undulata ‘Albomarginata’. 20 cm × 10 cm variegated foliage with stark white margins. Tall stems of lilac flowers.Hosta plantaginea — 20 cm × 30 cm bright green leaves. The white flowers are pleasantly scented. This species does best in a mild, humid climate. ‘Honey Bells’ is a cultivar with similar habits that is less demanding. It has scented lavender-pink flowers.‘Shade Fanfare’ — 20 cm × 15 cm leaves, mid green heart-shaped and edged with bright yellow. It really does prefer shade as the light margins will burn in full sun.‘Frances Williams’ — a sieboldiana type with 35 cm × 20 cm blue-green edged yellow-green foliage. Forms a large clump and has pale lavender flowers.‘Gold Standard’ — 20 cm × 15 cm leaves are bright golden yellow edged green. Very striking but does need shade from the midday sun. Pale lavender flowers.‘Green Fountain’ — narrow 25 cm × 10 cm bright green foliage and lavender flowers. Simple foliage and few flowers but very clean-looking. A great filler because of its dense growth.CultivationThe key to success with hostas is a loose, open soil with plenty of humus. They will not thrive in heavy clay, which impedes the root development, or very light sand, which tends to be too hot and dry.Work the soil over well and incorporate plenty of well-rotted compost. This will improve the structure of the soil, helping it to retain moisture while improving the drainage and aiding good root development.Plant your hostas so that the crown and emerging shoots are at soil level. Too high and the crown may dry out, too deep and leaves may start to unfurl before they are clear of the soil, which leads to soil in centre of the foliage — rather unsightly. Deep planting also provides a hiding place for slugs and snails, which are the only serious hosta pests. (Use commercial poison baits or home-made traps for slug and snail when the foliage is young and vulnerable.)Although hostas can tolerate drought, regular mulching and liquid feeding will keep the foliage lush and healthy through summer into early autumn. Some hostas have brightly coloured autumn foliage, an effect that can be enhance by drying off the plants from late summer.PropagationNew hosta cultivars are among the more expensive perennials. This has to be due to their fashion appeal because they are among the easiest plants to propagate.Simply lift and divide the clumps in late winter or very early spring. The growth buds will be very obvious and the clumps, while woody in the centre, divide with ease. Dust any large areas of cut tissue with flowers of sulphur as a fungal disease preventative, replant and water in.The growth usually continues unchecked and before long you can have hundreds of hostas. Even though the initial purchase may be expensive, their long life, easy of cultivation, hardiness and simplicity of propagation makes hostas very economical in the long run.

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