PLANT YOUR BORDER
This collection of plants grows best in a sunny or at most partially-shaded site with good drainage under their feet. Several will cope well with drier conditions but they universally dislike prolonged winter wet. Spend time clearing any perennial weeds from the site and breaking up areas of compacted ground. Then add plenty of well-rotted organic matter right across the site, adding horticultural grit if you feel your ground is on the heavier side.
After planting be sure to finish with a mulch of weed-free organic matter. This not only smothers annual weeds but also slowly improves the structure of the soil too. If you manage to work on the area this winter when the ground isn’t too wet or frozen, you’ll have a border ready to plant up in spring.
1 Start with the herbaceous perennials
There are three core herbaceous perennials to this border that will look best planted in groups snaking across the border. If you’re on a budget, try to ensure you have at least three of each to stop it looking too bitty. The amsonia (Eastern bluestar) is likely to be the slowest to establish, so if you’re going to plant extra, choose this one. Ask around with any gardening friends and you may find that you can lift a clump or two of their sedums or phlomis because they’re such popular plants. Add further compost to each planting hole and extra grit if you need to improve drainage, water in thoroughly and mulch around their skirts once you finish.
Leave all the plants to stand into winter and the dried seed heads will sparkle in frost or snow, only tidying them away if they collapse or as new growth begins to appear in spring. The phlomis can keep its leaves right through winter, so clear them away in time for the new growth to take over. All three perennials can be lifted, split and replanted once they have formed generous clumps. The phlomis is also easy to propagate from seed; collect your own in autumn or just shake the seed where you’d like to see new plants – but remember not to weed or mulch over them.
2 Add the grass and sedge
Plant your stipa in spring towards the back of the border and the smaller carex in a river along the front. The stipa needs plenty of space to spread into a large clump so beware overcrowding. Their flowers stand beautifully for months although you’ll be tempted to snip a few for cut flower displays – they look incredible in a tall vase with alliums. The carex also has flowers but these are fairly insignificant things albeit arching prettily. In spring cut out any remaining flower stems and comb through the clumps of both stipa and carex to pull out dead leaves. Large clumps of both can be propagated by lifting and dividing in autumn or spring; but on heavier soil it’s safer to do this in spring.
3 Finish with the verbena
Verbena bonariensis makes a fantastic light screen that can be positioned anywhere in the border and it’s useful to pad out a planting while slow growers are getting established. You can pick up plants in mid to late spring but if you want to plant in number it pays to make an early sowing in late winter or early spring to produce plants that will flower in their first year. Sow in a greenhouse or sunny windowsill and pinch out seedlings to ensure bushy plants. In future years take cuttings in spring to increase numbers still further.
You’ll find they start self-sowing around the garden too, appearing where they seem to be happiest, often in sharply drained areas such as paving cracks, gravel paths and against a sunny wall. Leave top growth on to catch the frosts and protect the plant, then cut back to new shoots in mid to late spring.