PLANT YOUR BORDER
This planting likes a moist, fertile but well-drained soil. Box and hosta show signs of scorch if they dry out. Planting in part-shade helps the soil stay damper in more free-draining conditions. First remove all perennial weeds, then work in plenty of well-rotted organic matter, which helps lighten and improve the drainage of heavy ground. Add extra grit if required. Give an annual mulch to retain soil moisture and provide nutrients.
1 Establish the box
Spring is a great time to establish new box plants. Soak the pot thoroughly before you plant and resist the temptation to enrich the planting hole; you’ll create a wet sump beneath its roots. Blight is understandably on the mind of anyone considering box, so choose from a reliable supplier. If you’ve lost box plants in the past, consider using Ilex crenata instead. Clip topiary in early June and again in September to ensure a crisp outline throughout the year. If plants seem to be struggling, boost growth with a general purpose fertiliser in spring. Although box is expensive and fairly slow growing, they’re wonderfully easy to propagate from semi-ripe cuttings in late summer. You can root them straight into garden soil but they’ll root quicker and with greater success in a cold frame.
2 Plant the crambe
Plant flowering sea kale either in early spring while still dormant, or in autumn. They don’t like disturbance, so choose a young plant and plant early to ensure minimal damage to its deep roots. Or, propagate your own plants from seed. Water in well, mulch and keep an eye out for slug and snail damage to young leaves. The incredible flower spikes are usually selfsupporting but put in a sturdy stake on exposed sites to give extra insurance against summer squalls.
3 Add the other perennials
The hosta, pulmonaria and aconitum are easy-going herbaceous perennials that can be planted in spring or autumn. Always wear gloves when handling the aconitum because all parts are poisonous. Soak the pots thoroughly before planting and water in well. During the first growing season, soak plants during any prolonged dry spells. If the pulmonaria suffers from mildew, cut back to ground level, water heavily and feed. You’ll be rewarded with a rush of healthy new growth. Slugs and snails love hostas so protect your plants from the start, using either organic pellets or baited traps. Tidying away old leaves and making sure there’s no obvious slug and snail hiding places nearby can really help. After three or more years the pulmonaria and hosta will have formed sizeable clumps that you can lift and divide in autumn or spring, replanting the healthiest sections. Aconitums can also be divided but won’t increase as quickly as the other two.
4 Finish with the tulips
Tulip bulbs are best planted in late autumn or early winter, in November or even December, when a cold spell has helped reduce the risk of soil-borne diseases. Order early to be sure of getting the cultivar you’re after. Plant the bulbs at more than twice their own depth, around 10-15cm (4-6in) deep. ‘White Triumphator’ is one of the more reliably perennial tulips if left in the ground, but you can boost next year’s display by deadheading, giving plants a balanced feed after flowering and resisting the urge to tidy away the dying foliage. Or, lift the bulbs once they’ve died back, storing the largest to replant in autumn.