Plant profile: baptisias
Baptisias have been grown in the UK since the 19th century, but are now enjoying a much-deserved spike in popularity, thanks in part to the many new hybrids
Baptisias are enjoying a muchdeserved spike in popularity, thanks in part, says John Hoyland, to the new hybrids
The prairies, woods and meadows of North America are a rich source of plants for British gardens. Baptisia australis, has been grown in gardens here since the end of the 19th century and generations of garden writers have extolled the virtues of its blue, pea-like flowers, its longevity and its adaptability. Until recently, though, there have been only a few other species of Baptisia grown, a couple of cultivars and no hybrids. Now, suddenly, dozens of new forms are appearing in nurseries and garden centres. And many more are on their way.
Plant breeders have been won over by the genus’s ability to thrive in poor soils, its beautiful foliage and handsome flowers. It is a member of the Fabaceae family and so related to peas and beans. The flowers are composed of large, outer petals that are referred to as the standard, two lower petals that are known as wings and, beneath the wings, two petals that are joined together to form the keel. These are the terms growers often use when describing colour variations in the flower.
It is common for Baptisia to be mistaken for another member of the Fabaceae family, lupins, but the similarity is limited to the new shoots and the flowers. Baptisia are not susceptible to the pests and diseases that attack lupins and will live for many years longer.
There are about 17 species of Baptisia, all native Americans. Baptisia australis, which is usually one of the parents of modern hybrids, has rounded, often glaucous leaves. Growing above the foliage in late spring are spikes of indigo-blue flowers that reach about 1m tall, sometimes more on rich soils. After the flowers are over the plant has a second flush of growth and by the end of summer it has matte-black pods, like small broad beans. Rattle them and you have the sound of mini maracas.
The other main species used in Baptisia breeding are the yellow-flowered Baptisia sphaerocarpa, named for its spheroid-shaped seedpods; Baptisia bracteata, a prostrate form with ivory-coloured flowers; and Baptisia alba. Surprisingly Baptisia alba hasn’t caught gardeners’ imaginations in the same way as Baptisia australis. I consider it a far more elegant plant, with duskycharcoal stems and racemes of creamy-white flowers. Young plants flower sparsely but I have one that after five years had 20 flower spikes. It flowers earlier than other species and is covered by hungry bumblebees.
The new hybrid flowers encompass blues and white as well as mahogany, brown and pink. Some breeders are focusing on bi-coloured plants where the keel of the flower is either a contrasting or a complementary colour to the rest of the flower. To meet the trend towards smaller gardens other breeders are producing shorter, more compact plants.
The new range of colours will mean more gardeners can find a place for them in their gardens. In my own I like the combination in the spring of Baptisia australis planted among white peonies with tall, blue alliums threaded though both plants. Later in the year the soft-green domes of the Baptisia are a perfect background for the sharp spires of herbaceous salvias. In a friend’s orchard I was impressed by pools of a pale-blue hybrid growing in rough grass with dark-blue masts of Camassia leichtlinii subsp. suksdorfii moored around them. I have also seen Baptisia grown as a sort of flowering hedge, in the way lavender is sometimes used. The flowers were cut down after they have finished and for the rest of the year the Baptisia formed a softly undulating enclosure for taller later-flowering perennials.
Whatever your style of garden or your taste in colour, it is probable that among the new wave of baptisias there are some that will enhance your garden. I will certainly be growing more.
Cultivation
Baptisias are undemanding plants that are easy to grow on well-drained soil in sun or part shade. The ideal conditions are a sandy loam in full sun but they will tolerate a wide range of soil types, including clay, as long as the soil does not become waterlogged in winter. Once established, they are extremely tolerant of periods of drought. Because of their long tap-root baptisias are more difficult to move than most herbaceous perennials, so choose where you want to plant them carefully.
Plants are going to be growing in the same spot for years so before planting dig plenty of compost or well-rotted manure into the area. On heavy soils add horticultural grit to the mix. Every few years mulch around the crown of the plant with compost. Baptisias do not like to be crowded out by other plants and are at their most vigorous when air can circulate around them. Nurseryman and Baptisia specialist Hans Kramer recommends not planting other plants too closely around them, particularly in the first year.
Baptisia sphaerocarpa establishes more slowly than other species and the stems have a tendency to flop over after the plant has flowered. If this looks too untidy you can either support the plant with birch twigs or metal hoops early in the year as it starts growing, or cut the whole plant down to a few centimetres above the soil after it has flowered. Cutting the plant down will produce a compact dome of fresh-looking foliage but you will lose the seedpods.
Some Baptisia – especially the modern hybrids – are reputed by enthusiastic marketing blurb to be unappealing to deer. However, you should be wary of such claims, a local muntjac deer enjoyed munching on ours, even when there were far tastier plants in the garden.
Dividing the main plant into smaller pieces is the usual way with herbaceous perennials to produce more plants. With Baptisia, the long tap root makes this difficult and the smaller pieces often do not establish. To have the best chance of success, dig up as much of the plant as possible in spring just as new growth appears. Dig deep and take as much root as possible. Cut the plant apart with a saw (or, do as I do and use an old bread knife) and replant the divisions immediately before the roots dry out.
Baptisias can be grown from seed, although only seed from species plants will produce new plants that are true to type. The seed has a hard coat, similar to that of a sweet pea seed, and will germinate more quickly if it is soaked overnight in warm water. Germination should take about a month but you will not have a flowering plant for three years. Stem cuttings should be used to increase named hybrids and cultivars but can be tricky to do even for specialist growers. To have the best chance of success, take cuttings in the spring and use a rooting powder. Hans Kramer says that about 30 per cent of cuttings do not succeed, which accounts for the relative high price of Baptisia compared to other herbaceous perennials.