Eremurus are clump-forming perennials with rosettes of strap-shaped basal leaves producing dense racemes of small star-shaped flowers on erect leafless stems in early to midsummer. They are followed by round seedpods the size of marbles that bear winged seeds. Leaves and flowers grow from a central crown from which the fleshy roots radiate giving the bare root crow starfish like appearance.
Site and soil
Eremurus originate from the dry grasslands and semi-desert of western and central Asia, therefore it can be difficult to mimic such growing conditions in the UK climate.
They require free draining soil. Choose the sunniest spot in the garden and do not plant in frost pockets. Though hardy, the young spring foliage is prone to frost damage. Avoid windy sites if growing taller species or cultivars.
The fleshy, shallow root system resents disturbance and competition from other plants. Keep soil cultivation (e.g. hand weeding or digging) close to the plants to a minimum to prevent accidental root damage. Ideally clear away any plants growing around them. They may cope with closer company of smaller bulbs or shallow rooted annuals.
Bare root crowns are available in early spring or summer. Plant as soon as possible after purchase. If the roots appear dry, soaking them in water for a couple of hours prior to planting may help. Handle the brittle roots as little as possible.
Prepare the site by incorporating organic matter such as garden compost. If the soil is heavier, to aid drainage, consider raising the soil level of the bed intended for planting.
Create a shallow planting hole 15-20cm (6-8in) in depth and wider than the roots. Position the centre of the crown on a mound of coarse grit, sharp sand or soil, so the central growing point is just below the soil surface. If planting in clumps space the crowns 30-90cm (1-3ft) depending on the size and cultivar vigour.
Mark the position of the plant with a cane or similar to avoid accidental damage when dormant. This would also mark a good spot for inserting a stake, if needed.
Potted plants may be available in spring.
Eremurus is not well suited for a long term container cultivation.
Watering and feeding
Once in active growth feed with high potassium fertiliser such as sulphate of potash in spring. If plants are damaged by late frost or are not very vigorous, consider liquid feeding with a general fertiliser once a month in late spring and summer.
Make sure that the plants are not prone to drying out when in leaf. The foliage will start dying down soon after flowering. When dormant in summer they enjoy dry conditions.
Although hardy, eremurus can be damaged by waterlogged soil. Application of dry autumn mulch such as bark or gravel may be beneficial, but avoid covering the centre of the crown.
Eremurus comes into growth early in the season and the shoots are prone to frost damage. Protect the new growth with fleece or cloches.