Growing Annuals and Perennials, and Biennials – Expert Advice
Growing Herbaceous Plants
Where colour and interest are needed quickly, as for instance around a new home where the garden has been neglected or is as yet unmade, biennials, annuals and perennials, like numerous bulbous flowering plants, come into their own. They can be used to ‘hold the fort’ until long-term plans have time to mature, as well as being included in the permanent scheme of things.
Colourful and very pleasing displays can be created with theseunder widely differing conditions. Their versatility is such as to make them useful to both the town gardener with little space to play with and his suburban and country counterpart who can contemplate more ambitious planting schemes.
The Mixed Border
A modern development well suited to gardens of modest size is the ‘mixed border’ in which annuals and perennials, biennials, bulbs and selected flowering and foliage shrubs are grown together. This has the obvious advantage of saving space, for all the above-mentioned groups of plants are grown in an area that one of them would normally occupy; and it has the merit of giving, with skilful planting, a longer period of interest and colour.
I am all for adopting measures like this where they have positive, practical advantages to offer. When making a mixed or conventional herbaceous border I consider it a mistake to give it a straight edge bordered by a path. I find this harsh and unsympathetic.
Much more pleasing is to have grass running up to the border and to shape its edge. This brings the plants right out into the grass.
The main advantage when growing annuals, as I see it, is that they will give you a quicker and cheaper display of colour than any other flowers could ever do. Also, they will thrive in almost any, provided it is worked down to a fine tilth. In fact, they must not have rich soil or a lot of leafy growth will be made at the expense of flowers. A well-drained, light soil with plenty of sunshine is what they really appreciate.
One difficulty in gardens where spring bedding plants like wallflowers, polyanthus and forget-me-nots are grown is that, quite often, seeds of hardy annuals cannot be sown in March or April where they are wanted to flower. I get over this problem by raising my annuals in soil blocks.
I stand the soil blocks in boxes, sow two or three seeds on the top of each block and thin the seedlings out when they are about 1 inch high. The young plants then go out when the bedding plants are removed. They begin flowering in June and if the flowers are removed after they have faded, I get a show of colour which lasts until September.
For filling in odd gaps in the herbaceous border, growing annuals is ideal. Any space noticed in April or May can be dealt with in this way, either by sowing seeds directly in the border or by planting out young plants from soil blocks following the system described above. Their use in mixed borders has already been mentioned.
Although, compared with herbaceous annuals and perennials, biennials are a small group of plants, they are still invaluable in the garden for set-piece displays or for ‘filling in’ while longer term plans mature. Most of us would want to find space for such favourites as the Canterbury Bells, Wallflowers, Foxgloves and Sweet Williams.
Planting and After Care
The best aspect for a plant border when growing annuals and perennials, and biennials too, is south or west; I would place east next with north a poor fourth, for it is very restrictive in that you are only able to grow plants which are happy with very little sun.
The background to the border is rarely given the consideration it deserves. A stone wall looks superb, but it is unlikely that it will be where it is wanted. When you have to create a background there is not much to beat a cupressus, thuya or beech hedge. One or other of these will act as an excellent foil for the colours of the flowers.
Fencing does not serve the same purpose, and where it does form the background for a border I would always endeavour to mask it with tall-growing plants. A fence is not sympathetic to plants in the same way as a close-knit hedge.
A tall fence can be masked with rambler or climbing, Clematis montana or Polygonum baldschuanicum. I also like to erect posts here and there in the border itself and use these as supports for roses like Paul’s Scarlet Climber or Dorothy Perkins.
Arrangement of Plants
When working out planting schemes, it is more important to place plants so that they form pleasing shapes and patterns than it is to get perfect colour blendings.
I always try to arrange things too, so that early flowering border plants which may be dull or even unsightly for the rest of the season are reasonably well masked by later-flowering plants. It is a rule, and a good one, with perennials, annuals and biennials, always to make bold plantings of each individual species or variety. It is also true that varying the shape of the groups so that there is no uniformity, and varying the heights to carry the eye from one plant to another, adds immensely to the attractions of a border.
Broadly speaking, tall plants at the back look better, the medium-sized plants in the middle and the short plants in the front – but you don’t have to keep too closely to this formula. Bring some of the medium sized plants to the front occasionally and drop back some of the short ones so that all manner of pleasing shapes and contours are created. A bit of clever juggling is all part of the fun of gardening.
No soil can possibly be ideal for every purpose for, in addition to the many plants which are happy in any reasonable soil, there are those which need an acid rooting medium and others which grow best under alkaline conditions. What most of us would like – but we usually havn’t got – is a nice fibrous medium loam with plenty of body in it. What we are most likely to have to cope with is a soil which is either too light and free-draining or too heavy and water retentive for the needs of most plants.
Fortunately there is a fairly easy way of overcoming both tendencies. This is by digging in moist granulated peat or other humus-forming material to improve the soil texture. Heavy clay can be vastly improved by such treatment and in time can be turned into a first-class growing medium. Light, sandy soils can be so treated but the effect is more short-termed.
I like to work clay soils in the autumn so that they can be left rough for the rain and frost to break down. Never attempt to dig such soils when they are so wet that your boots get totally covered.
Some plants do best in, and in fact prefer, acid soil; others will only grow well in limey soil, so it is a good idea before sowing seed or planting to find out which kind you have.
This is easily done with a simple soil testing kit, obtainable from garden supplies or nursery. If it is shown to be very acid, or the plants you are putting in, prefer limey soil, then a dressing of lime should be made about a couple of months after digging. The best type to use is hydrated lime and the amount to apply will depend on the degree of acidity. Three ounces to the square metre would be an average dressing. On light soils, though, I would recommend the use of ground limestone for this purpose as this is less easily leached through the soil. On average, this needs to be applied at about twice the rate for hydrated lime.