Growing Annuals and Perennials – Planting and Aftercare
Growing Annuals and Perennials
In general, March and early April is the most favourable time to plant herbaceous perennial plants (although when weather conditions are favourable I like to start this job in February), but there are some exceptions to this recommendation. For example, many gardeners like to move, kniphofias, hellebores and other plants which take quite a time to settle down in the autumn so that they get away quicker the following spring and are not so badly affected by dry spells at that time.
The trouble which you can experience with autumn planting in anywhich tends to be on the heavy side, is that heavy rainfall and a tendency to water logging can delay establishment and so result in damage or loss. Intense cold such as we sometimes have, also leads to losses among autumn planted perennials.
I like to prepare the planting holes for the smaller plants with a trowel but for the rest, of course, I use a spade. The important thing is to work the soil well in among the roots. Be especially careful, too, to firm the soil well around the roots for if they do not come in close contact with the soil they wither and die.
Where annuals are to be grown, the soil texture may need improving but rich soil is certainly not wanted for annuals which will produce a profusion of leaves and fewerwhen given such conditions. At most, on hungry soils, I would put down a light dressing of bonemeal some weeks before sowing. (This fertiliser is given up slowly, and in modest quantities will do nothing but good.) There is no doubt at all that the key to success with growing annuals, is the preparation of the seed bed.
Staking, thinning, weeding, forking over the soil when it has been panned down by rain, removing dead flowers to encourage further flowering, feeding with slow-acting fertilisers, and, of course, lifting and dividing (except in the case of those plants which resent being moved) every three or four years these are the jobs which we must attend to whenever we grow perennial flowers.
For staking perennials, I use only short pea sticks – last year’s pea sticks as far as I can.
Those gardeners who do not have ashould still buy pea sticks for this purpose, for I am sure that this is the cheapest way to provide support for the plants, in the long run. Pea sticks for use with herbaceous plants will usually last for a couple of years. To provide an example of what I do with these sticks, let us suppose that the plant we want to support has an ultimate height of about 2 1/2 feet.
The sticks I put around the clump would be 1 1/2 to 2 feet tall, and if these make the border look like a timber yard when they are first put in I know that by the middle of June they will be completely hidden from view. The plants grow up through the sticks and are given all the support they could possibly want. The only exceptions I make to this kind of supporting are for delphiniums and lupins; these I give separate stakes for individual spikes. When a flower spike is pressed by the wind, the support should allow it to move a little and then bring it back gradually and without damage when the pressure is no longer there. For securing perennials to stakes some soft material must be used, like raffia, fillis or twine.
Also, with plants like these which make rapid growth, it is important to allow plenty of room for expansion when the ties have been made. One way of doing this and yet having a firm tie at the same time is to take the tying material round the stake, knot it and then take it loosely round the stem, knotting it again. The stem can then expand and still be held firm enough for all practical purposes.
The most important time to work over the soil in between the plants, without of course disturbing the plants’ roots, is just before growth gets into its stride in spring, and this is the time, too, to work in a light dressing of a slow-acting fertiliser like bonemeal or hoof and horn. Never feed plants with quick-acting fertilisers, or unwanted growth will be produced at the expense of the flowers. Dead-heading is a good old gardener’s term for removing the flowers of ornamentals as soon as they have gone over.
This is a good practice for the very worth while reason that it often encourages plants to produce another crop of flowers, but it also keeps the border tidy and that is important, too, I always feel.
If tall bearded irises are grown, cut down the foliage to within about 6in. of the ground in the autumn to lessen the chances of damage from disease, and with delphiniums cut back the stems almost to ground level at the end of the season and cover the crowns of the plants with well-weathered ashes as a protection against winter damp.
The crowns of kniphofias get useful protection from tying the leaves together at this same time. Thinning, if you are a newcomer to gardening, is a task which you’ll do with some misgivings, but as you’ll soon finds out it can pay good dividends.
To take delphiniums as an example again, if the growths on each plant are reduced to about six in number it will be found that the spikes are far superior to those on plants left unthinned. In three to four years after planting a border of perennials it will be noticeable that the quality of the flowers is in many cases falling off. This is due to the exhaustion of the plants and the gradual depletion of food reserves in the soil.
All this can be put right by lifting the plants. It is necessary for thin sowing and the plants can be finally thinned out about two to three weeks after the seedlings have been first thinned.
I think a lot of gardeners go wrong over spacing when flower growing. Annuals want plenty of room to develop; the minimum for the smallest should be 9in. and most will fill out to 15 to 18 inches. It is worth remembering, too, that in showery weather in May or early June it is quite possible to lift some plants, if this is done carefully, and replant them successfully where there are gaps.
If the weather is not favourable after sowing there are quite likely to be gaps which will have to be filled. After this stage, your main preoccupation will be to keep the weeds under control – either by hand or by using a hoe delicately in among the plants. In dry weather it will be necessary to water the plants for, with their root systems still only partially developed, any serious shortage of moisture will have dire results.
Growing annuals which need staking, I like to stake early. I stake all my growing annuals except those like larkspur, which get a double stake – with twiggy pieces of birch. These I insert when the plants are about 8 to 9 inches tall and they then grow up through them and obscure them from view.
It is very much like the way I treat perennials. Do not allow finished flowers to remain on the plants: dead-head them as quickly as possible so that the plants will use all their energy to produce more flowers and not divert it to the production of seed.