The last three summers in the East Midlands have been drier than the long-term average. Not dramatically so, but enough that plants which used to perform reliably in average conditions have started to struggle. We have been keeping notes on what has done well and what has not across the gardens we maintain and visit, and the picture is fairly consistent.
What dry summers actually do to a border ¶
Most perennials can tolerate a dry week or two. Problems start when dry spells extend to three or four weeks, particularly on sandy or free-draining soils. The plants that struggle first are those with large, soft leaves and shallow root systems. Hostas, astilbes, and many of the moisture-loving geraniums start to look tired by July in a dry year. The plants that hold up are those with deep taproots, fine or waxy foliage, and a Mediterranean or prairie origin.
The plants we keep recommending ¶
Achillea, salvia, echinacea, and stipa have been the most consistent performers across our clients' gardens over the past three seasons. Achillea 'Terracotta' in particular has been remarkable: it flowers from June to September, needs no staking, and looks better in a dry year than a wet one. Salvia nemorosa 'Caradonna' has flowered for longer than any other salvia we have tried, and it has come back reliably even in gardens with heavy clay that dries and cracks in summer.
Soil preparation for drought-tolerant planting ¶
Counterintuitively, drought-tolerant plants often do better in poorer soil than in heavily amended beds. Adding too much compost to a free-draining soil can encourage shallow rooting because the plants do not need to go deep to find moisture. We add a modest amount of grit to heavy soils to improve drainage, and we mulch with a 50mm layer of gravel rather than bark, which keeps the surface cool without retaining too much moisture around the crown.
What to avoid in a dry garden ¶
Avoid plants that are described as 'moisture-loving' or 'bog garden' plants unless you have a naturally wet area. Avoid planting in large blocks of a single species: if one plant struggles, the whole block looks bad. Mix species with different root depths so they are drawing water from different levels of the soil. And avoid planting in July and August if you can help it: autumn planting gives roots a full season to establish before the following summer's dry spell.
A simple border recipe that has worked for us ¶
For a sunny, free-draining border of about 10 square metres, we have had good results with a mix of five Achillea 'Terracotta', five Salvia nemorosa 'Caradonna', three Echinacea purpurea 'Magnus', and seven Stipa tenuissima. Plant the stipa in a loose drift through the middle, the achillea and echinacea at the back, and the salvia at the front. It flowers from June to October, needs cutting back once in late February, and has survived three dry summers without supplementary watering after the first season.
If you want to see this summer's plant list and what we are currently recommending, take a look at the seasonal selection on the site. We can source and plant any of these as part of a new project or as a standalone visit.