How to grow and care for Acidanthera

How long does it take for acidanthera to grow and flower?

Acidanthera can be quite slow to appear after planting, first developing its root system underground, but once foliage appears, it grows very quickly. It will produce its striking flowers about three months after planting, in late summer or early autumn, and its foliage will look good until the first frosts.

Where to grow acidanthera

Acidanthera makes a wonderful display when planted in drifts in a mixed border or cottage garden. It also complements a prairie-style planting of grasses and late-flowering perennials, and is a great addition to the cutting garden. If you grow it in a pot, position it in a place where you can get close enough to appreciate the rich fragrance of its blooms.

How to plant acidanthera

Acidanthera grows from a bulb-like structure known as a corm, and many sellers refer to it as a bulb. While it’s not strictly necessary, soaking the corm in room-temperature water for a few hours before you plant it can stimulate it into growth more quickly.

Acidanthera comes from East Africa and can tolerate temperatures down to -5ºC. However, to give them the best start it’s wise to wait until late spring to plant the corms outside, when the soil has begun to warm up. Or, if you’re growing them in a pot, start them off indoors and move the pot outside when all danger of frost has past, usually from late May onwards.

If you plant the bulbs or corms at a depth of 15cm, the flower stems will not need staking as they grow. For impact, plant them in drifts, digging a hole 15cm deep and at least 50cm across, scattering 20 or so corms on the soil so that they are approximately 10cm apart. Refill the hole and firm it down, then give the whole area a good watering to settle the soil around the corms.

How to care for acidanthera

If you’re growing acidanthera in a pot, keep it well watered. Once the foliage appears, add liquid plant feed to the water every few weeks to encourage flowering. If growing it in the garden, use a soil conditioner such as home-made compost or composted manure to add organic matter, provide nutrients and encourage organisms that will create a healthy soil. Once planted, treat your acidanthera like any other herbaceous perennial. Deadhead after flowering to ensure the plant does not put any energy into producing seeds.

If you’re gardening in coastal and mild areas in the south of the UK, you can leave acidanthera in the ground over winter, allowing the foliage to die back, and cover the area with a thick mulch to insulate the corms. Otherwise, you have two options: dig up the corms, compost them and plant fresh corms the following year; or lift them, allow them to dry and store them in a dark, cool, frost-free place before planting them out again in late spring or early summer.

What if your acidanthera isn’t flowering? Acidanthera can make a slow start in cool or dry conditions, so be patient. If you’re treating your acidanthera as a perennial - either leaving it in the ground over winter or planting it again the following year - you may not get many flowers in its second season. This is because producing foliage and flowers uses up the energy stored in the corms and they may take a year’s break from flowering while they replenish their reserves.

To improve your chances of getting a second display of flowers, feed the plants well while they’re growing, condition the soil annually (or replace it if growing acidanthera in a pot) and use a liquid plant feed when the foliage appears.

How to prune acidanthera

Acidanthera does not require any pruning. Once the foliage is damaged by the first frosts, lift the corms, cut off the foliage and add it to your compost heap.

How to propagate acidanthera

During the growing season, your acidanthera corms will produce smaller corms (known as cormlets). You can separate these when you lift the parent corms and store them for planting the following year. They’ll produce foliage for the next few seasons and are likely take a few years before they reach their ultimate flowering size.

Pests and diseases

New growth of acidanthera may be damaged by slugs. Also, if the soil is too wet, the corms could be damaged by mould or gladiolus corm rot.