Success with perennials
Get more blooms for your £££s with Alan’s guide to these versatile plants
Perennials suit a variety of circumstances. A garden without them is missing out
For uplifting colour and their ability to fill a border, perennial plants are unbeatable. They offer variety of outlook and seasonal change. Their range of heights, from just a few inches to more than six feet, and their variable habits – from the tal l and statuesque to the billowing cloud or the modest creeper, means they will suit a variety of circumstances and gardens – or containers – of all sizes. In short, a garden without them is really missing out. A perennial simply means a plant that will live on indefinitely, as opposed to an annual, which f lowers, sets seed and dies within 12 months, and a biennial, whose seeds are sown one year to f lower the next. Strictly speaking, trees and shrubs are perennials, but the term is most commonly used to descr i be smaller, less woody plants. Many die down in autumn to just their roots, to emerge afresh the following spring and these are more accurately referred to as herbaceous perennials. All in all, perennial is a rather mundane title for an invaluable group of plants that are in general easy to grow and – mercifully – easy to multiply. Some perennials are evergreen and will not disappear from view; among them, ophiopogon ( black mondo), armeria (thrift), euphorbia (the spurges), dierama and Erysimum ‘ Bowles’s Mauve’ ( the purple wallflower). This little lot are brave enough and hardy enough to retain their foliage – and sometimes their interest – throughout the winter months.
Tender treats
But there are a few garden perennials that are frost-tender – penstemons, many of the perennial salvias that are now available in a huge variety, and the likes of Cosmos atrosanguineus ( the one that smells of chocolate) – and will be killed by severe f rosts. But recent mild winters have meant that many of t hem emerge unscathed in the spring – at which point their tat ty overwintered stems and foliage can be cut right back to young emerging buds and shoots that will produce fresh growth and flowers for the new season. As ever, there are exceptions to every rule, and some perennials will not go on for ever. They are referred to as ‘short-lived’
Once they’re planted, perennials just need a handful or two of feed each year R
perennials, but don’t let that put you off growing them, since they wi l l often produce seedlings or offshoots that can be grown on to take over from the aged rootstock that finally runs out of puff and disappears. Lupins, aquilegias ( granny’s bonnet), Lobelia cardinalis and Lychnis coronaria (rose campion) all fall into this category, but it would be a shame to avoid growing them when they add so much to beds and borders in their admittedly fewer seasons of glory. Whatever their life span, perennials fill a space quicker than most shrubs and cost less (especially if you propagate your own), which means you can fill an area with them and then, after a year or two when you have made up your mind what you really want in a particular spot, they can be dug up and redistributed – either in the garden or among your friends. That’s their other advantage – they seldom mind being dug up and moved, provided you avoid disturbing them in the summer when they will be full of leaf and f lower and inclined to wilt. If you are a lazy gardener… let me rephrase that… if you are a gardener with little time on your hands, you will appreciate a few perennials that can be left to their own devices. Once planted in the right spot, they just need a handful or two of feed each year and a good soak in periods of prolonged drought. Peonies are top of the list here. They will happily stay in one spot for decades – in fact they resent being moved, and will f lower their socks off each spring, provided you do not bury their yam-like roots too deeply (the prime cause of them failing to flower). Make sure they are only just under the surface of the soil. Those fat roots also help them to resist drought. Hostas, too, will go on for years without being moved – even in large pots.
Choose the right spot
The secret of success, as always, is to find the right perennial for the right spot. Some are happy in shade – ferns and hostas, astrantias and some euphorbias – while others crave full sun – delphiniums and lupins, agapanthus and bearded irises. Even by listing them I am giving you an idea of their infinite variety, their versatility in terms of position in the garden, and the fact that some of them overwinter with a dense mat of fibrous roots, while others have food storage organs – like the iris’s fat rhizomes – which
act like a camel’s hump and see them through the worst of the weather. Do your homework before you plant them. Check their f lowering season, to avoid colour clashes and to ensure your garden has interest for as much of the year as possible. Check their eventual height (very important in terms of being able to see the shorter ones that are best planted in front of taller varieties), but also their spread. Discovering that a plant is a spreader, and will move sideways quite quickly, can save you money, but it can also help you to avoid a plant that will swamp its neighbours if space is limited.
Plan your planting
There is no need to plant so that the ground is covered in the first season after planting, but if you really do want ‘instant effect’ that is an option. Conversely, don’t save money by planting things a metre apart – the effect will be spotty and irritating to the eye. But then that’s the thing about perennials – you can buy smaller potfuls, which are more reasonably priced, and plant them more thickly, or you can buy larger ones and split them up into smaller chunks before you plant them. Neat – and practical. And once you have a plant that you love, regular division of the clumps (every three or four years) will allow you to increase your stock at no cost. And that’s why perennials are such good value.