Emergency gap fillers

What can you do when gaps appear in your beds and borders? Plantsman Graham Rice discusses reliable 'fillers' to save the day

In the height of summer we expect our beds and borders to be full, overflowing with flowers and foliage. But, sometimes, there are gaps. Plants become diseased or die unexpectedly, biennials may have extended their season so impressively that we simply left them – but now they must be replaced.

So in the middle of summer we need are plants that look good now, and that are available in the garden centre or RHS plant centre – mail order plants are often too small to have impact and they may not arrive till October. Here’s a few suggestions for plants that should be available in garden centres in July and in large enough sizes to make an instant impression.

Crocosmia x crocosmiiflora 'Columbus'Crocosmias are now seen in garden centres in bud and in flower; they have a long season and their slender foliage and upright growth allow you to slip them in wherever they’re needed. Look out for ‘Buttercup’ (yellow), ‘Columbus’ (gold - see left), ‘Emily McKenzie’ (dark-eyed orange) and ‘Jackanapes’ (orange and yellow bicolour).

Dark-leaved dahlias with single flowers, such as those in the Mystic and Dark Angel series, reach a very manageable 60cm (2ft) in height and bush out quickly once planted, especially if deadheaded. They will flower until frosts, in a wide range of colours, and their bronzed foliage adds richness and contrast.

The pink-and-white bicoloured Gaura ‘Rosyjane’ is valuable not only as a gap filler, but its tall and whispy growth can be slipped in between plants even in a well filled border where a little extra star quality is needed.

Hostas, by contrast, are ideal where there is an empty shady space to fill. ‘Honeybells’, ‘Invincible’ and ‘Royal Standard’ all feature bold, green foliage and fragrant pale lavender or white flowers. And hostas are so accommodating that if you decide, at the end of the season, that you put them in the wrong place for the long term then you can easily move them.

Finally phlox need a mention. Recently introduced types including the Flame and Peacock series have been developed to stay fairly dwarf and in their first year may even be shorter than their mature height. Sold in flower, simply choose the colour that works in your situation.

It’s also worth a reminder that planting pots in summer into borders which may be full of roots - even where there are gaps - requires some spot watering from a can or lance, and a dose or two of liquid feed. But in a few days you’ll never know your border had embarrassing gaps in the first place.

Get more ideas and inspiration for your garden from the RHS book, The Encyclopedia of Perennials, edited by Graham Rice.

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The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.