Yellow winter aconites are flowering in their full glory at ground level. Snowdrops have been out for more than three weeks. On calm days gardening has become a joy again. If you are planning or replanning a new border or a new series of flowerbeds what, from experience, would I urge you to do?
The first commandment is not to repeat my worst mistake. Taking on a newly bought garden, I was so keen, aged 41, to make a pretty picture that I never stopped to address its underlying canvas, the soil. I struggled until I saw sense after envying the better results in borders whose owners had begun by working on the soil. I now make amends by using Melcourt SylvaGrow shredded manure in 50 litre bags, recommended by the RHS (countrysupplies.uk.com is a keenly priced source, also supplying big orders in bulk). I fork it well into beds being prepared for new planting. At this time of year I then scatter bonemeal over the surface, ideally 3 ounces per sq yard, and fork that lightly in too.
When planting I use a slow release fertiliser, Osmocote or Vitax Q4 being two favourites, picking the mixes graded on their packets as suitable for perennial plants. Scatter some granules in each hole that you dig for planting and in any soil you use to re-fill it. In her famous French garden at Le Vasterival near Dieppe, the late Princess Greta Sturdza insisted that gardeners should spend three times the cost of a plant on improving the soil before planting it. Border plant prices have soared since her lifetime, but her garden is a living witness to the value of this principle.
The second commandment is not to plant too closely. We all do it and this bad habit is getting worse, backed, understandably, by many designers who need to make a good show quickly for customers. The density at which young trees are planted in the name of carbon capture, reforesting and saving the planet appals me. A high proportion of these overcrowded trees die or have to be thinned. At the level of border plants, five plants to a square yard is usually a very generous density, three to a square yard being fine for most of the taller ones: they can be divided if they flourish.
I much prefer to pay for a bigger well-rooted plant which I can split rather than buying “one litre” plants online, unseen. One litre plants, mass-produced, have a way of being sent out in one litre pots before they have fully rooted down into them. I would rather visit a nursery, pay more for an older plant, divide it on its arrival and then grow the divisions on in my garden’s soil, their future home.
Sedums, asters, irises, phloxes, hardy geraniums and heleniums are favourite choices for borders, each of which will split easily if cut through by a sharp spade, preferably on a fine day between now and mid-April. If you want to fill a long border on a budget, buy bigger plants in ones and twos only, split them into many more and then grow the bits on for a year in a special bed. Meanwhile, improve the border-to-be’s soil and fill in the gaps with temporary annuals and smaller varieties of gladioli, planted from April until mid-May.
Here is a principle for big borders and another for smaller flowerbeds which run round a garden’s perimeter. In a big border, try to repeat groups of your favourite plants at longish intervals down the entire length. Repetition draws the eye down the border, helping it to jump intervening dullness and to fix on each repeated group when in season. Long borders are best laid out to be viewed down their length, not head on, faults and all.
In a smaller garden I like to dot one good plant around in ones and repeat it. This repetition draws the eye round the garden instead of drawing it to the one and only clump of the plant, due to be dull when its season is over. Dotting, not grouping, is a liberation.
Height is crucial too. Ignore the old rule that the height of a border’s tallest plant should never exceed half of the border’s width. Few of us would grow hollyhocks if we obeyed that dull principle. The problem is not so much the height as the solidity and shape of the plants which attain it. Those with long spikes of flower, verbascums being good examples, are not a tall presence for very long. Being colourful, like candlesticks, their flower stems give bright height and are then cut down: they lift an entire border when planted in a middle to back row. Plants with upright vertical stems are invaluable too, from biennial Salvia turkestanica to the excellent spiky veronicastrums for spires of flower in August.
I value see-through plants whose height is delicate and not obstructive. I use some of the taller thalictrums at intervals down the backbone of my unbacked main border and I love the way that Elin or Black Stockings soars up above surrounding perennials, framing the view beyond but not blocking it. I am also fond of a wild hollyhock, Althaea cannabina, transparent to heights of up to seven feet and covered from August onwards with small pink flowers. It needs no staking and as it seeds itself freely, one plant is all you need to buy.
What about colour planning? Commandments on this subject proliferate, but the changing pattern of the weather makes many of them obsolete. Who knows now what will flower with what else and when? Subtle pairings may never coincide. It is at a macro-level, for once, that colour-planning still pays off. Limit your border’s colour range slightly, preferring clean and clear colours rather than streaky rose-mauve. One-colour borders usually become boring after a year or two, with the exception of an all-white scheme.
I still recall a City type who cornered me after a lecture, before the mid-1980s Big Bang, and told me he wanted a garden that was “white and smelly”: could I give him the plants to write down? How pushy, I thought, but I have often remembered him and his strongly scented aftershave. In an enclosed town garden, most often enjoyed in the evening, nothing but white flowers with a good scent are bewitching, especially if punctuated by evergreen shrubs with light-reflecting leaves.
Lastly, should you put shrubs, roses and perennials together or just perennials for a purist’s perennial border? If you have room, I much prefer a mixed planting, one which uses shrubs like abelia or cistus or the lovely June-flowering Viburnum hillieri Winton, up to six feet high and wide but willing to grow in light shade as well as sun. The shapes and scale of such shrubs, including shrub roses, hold a long border together if they are spaced as individuals at wide intervals down its middle rank. As for the perennials, make your own choices, but remember they are constantly being selected and improved. One of the aims in this column is to keep you up with the best of a changing range. Start planting, and go on reading.