Planning and Planting Hardy Perennials

Width of Border

Whatever type of border you decide to plan and plant its success and potential interest will depend not only on a well-chosen site, well-prepared soil and the right selection of plants, but on its width. The narrower the bed, the lower the plants should be. Nothing looks more incongruous than plants flowering at 4 or 5 ft. in a bed only 4 or 5 ft. wide. They inevitably harm dwarfer, choicer plants growing beside them, regardless of aspect. A safe guide in selecting plants is to measure the plantable width of the border in feet, and halve it to arrive at the maximum height of plants it should contain. This restricts a 4 ft. wide border to plants of no more than 2 ft. tall, but a little latitude can be allowed for the erect, spikey plants, such as kniphofias, to exceed the limit by a few inches. This is a rule that can be applied to any type of border-island or one-sided, bearing in mind that in island borders the tallest plants are placed in the centre, and in one-sided borders they are planted at the back.

Planning and Planting Hardy Perennials

Grouping should also be considered. Where space is very restricted and where variety is preferred, then there is a case for growing one plant only of each kind. But there is never any point in growing a single plant of the same kind in more than one position in the same bed or border. If the site is large enough, then plants should be grouped in threes, at least, in a bed of about too square feet in area, and in groups of up to to to 15 in the largest beds of a I ,000 sq. ft. or more.

Spacing Plants

The space between plants in a group, should be less than that between the groups themselves. This is because the plants in a group will usually grow and mass together effectively when in flower. But they will probably differ in form and habit from neighbouring groups, and will need extra space to allow for this as well as to allow for vital light and air to give sturdy growth and for access for maintenance. The average spacing should be about five plants to the square yard. If, for example, groups are of five plants of a kind, this gives a planting distance of about 16 in. from plant to plant within a group. But the space around the group, up to the outer plants in adjoining groups should be 20 in. Spacing depends on the vigour of the plant; a single plant may occupy a square yard or nine plants of a dwarf, slow-growing plant may occupy the same area.

Do not allow the more robust or rapid spreading kinds to overshadow or encroach on those that expand slowly. Those plants with a similar habit and vigour should be placed near to each other to avoid harmful competition. If you are prepared to plan you own bed or border, it is better not to use a stereotyped plan unless you are quite sure that the plants offered are suitable for the site. Making your own plan is not difficult.

Planning on Paper

First obtain a sheet of squared paper-each square inch subdivided into tenths. Using the most convenient scale that fits the paper, draw the outline of the bed or border. Within this outline, group spaces can be pencilled in faintly to begin with, once you have decided roughly on the area each group should occupy depending on whether variety or a more massed display is preferred. A large variety of plants will call for smaller groups but a square yard at least will be needed if groups are to be large enough for massed colour, depending on the total space available.

It is better to space each group by means of numbers. If there are to be, say, 36 groups in a bed, get the numbers one to 36 down on paper, spaced over the area, and when you are satisfied draw in the outline of each group as indicated on the sample plan. Using the list of plants you have already chosen, the placing of each one becomes a stimulating task, as you take account of height, spread, colour and flowering season. At this stage it is useful to know something about the habits of the plants and this is where the descriptions of the plants which appear later will prove helpful.

If in the process of making a new bed or border, an error in placing occurs it will show up during the first flowering season. Perhaps a dwarf kind should have been nearer the front or vice-versa, or two colours do not blend well. This matters little, for a switch can easily be made in autumn or spring, provided a note is made when the error is seen.

W hen to Plant

Generally speaking, autumn planting is best whether you are making adjustments or planting a complete new bed provided the soil is in clean, friable condition. It may not be possible to obtain delivery of plants from a nursery in early October, the ideal time, but the whole of October is usually safe for planting except on heavy, sticky soils and in the coldest parts of the country. In warmer or drier districts and on well-drained soils, it is safe to plant in No ember too, except for a few kinds, notably Icier (malt’s, erigerons, pyrethrums, Scabiosa nieusua, nepetas and some of the grasses, ^^ hid) ii is safer to plant in spring. In autumn the soil is still warm and new roots form quickly, so that in spring plants soon make up growth and do not lack for moisture. Watering in is seldom needed in autumn, but in spring it is often necessary.


Planting a new bed poses few problems if you have a plan. When the consignment arrives, unpack and stand each plant or bundle upright, and sprinkle with water if dry. If the bed or border is all ready with its marker sticks or labels for each group in position, placing will be easy, but do not, if you can avoid it, lay out the plants too early lest sun or wind dry out the roots before they are safely covered with soil. If the soil is wet and sticky, move about the bed on one or two short planks, and do not tread in each plant too firmly. Lighter soils may be too dry, and if when you try to make a suitable hole with a trowel, you find that the soil tends to run back, then puddling is the answer. This is simply a matter of pouring water from the spout of a can, till the hole is almost full. The water will quickly soak away and then you can enlarge the hole sufficiently to take the plant and having inserted it with its roots well spread out, draw round some of the dry top soil and make a loose tilth round the plant.


In spring, the soil is usually moist enough for planting until about mid-April, although even in March the soil can be so dry that puddling is necessary. If, after planting, plants show signs of distress, whether or not they were watered in initially, do not splash water over them. It is the roots that need moisture and a mere surface watering can be harmfully deceptive as it may erode the soil, expose the roots or cake the surface without soaking in. What the plants need is a fine spray; this takes longer, but will penetrate more readily to the roots, with far less waste of water. The same method, preferably using a sprinkler with a fine nozzle, should be used during a summer drought on established plants which are showing signs of distress; it is best done in the evening, and after each overhead watering, especially on a newly planted bed, it is worth hoeing or raking over the surface, as it dries out again, so as to retain a fine tilth, a top layer of loose fine soil in. thick, which enables growth to keep fresh for much longer as water is drawn up from the soil below.


A new bed, with soil well-prepared will not need feeding for the first year or two if it is reasonably rich in humus. Sand, gravel, chalk or clay soils are often shallow and lack humus. Although leaf mould is hard to come by, peat is easy to obtain and apply, and is an excellent form of humus for such soils. It is useful by itself, either dug in or applied as a mulch that will retain moisture and keep down weeds. But if it is used in conjunction with an organic fertilizer it is most effective in promoting good growth. The best method where plants need both a feed and a mulch, is to apply the fertilizer in March, at about 2 oz. per square yard and immediately hoe it in to the top 2 in. of soil. This is worth while on any bed or border after the second season, but if a mulch, too, is needed, this should be applied during April or May, depending on weather, type of soil and locality. The soil at this time is warming up, and to mulch too early in late districts may retard growth a little, though it will catch up later. The warmer the district the earlier you can begin feeding, hoeing and mulching. Before peat is used as a mulch it should be thoroughly moistened (dry peat can absorb up to eight times its weight in water); in this condition it is easy to spread over bare patches of earth between the plants to a thickness of to 1 in. If you fork over a bed or border in autumn or winter, a peat mulch applied in spring will largely disappear, though it will continue to do good, as a soil improver.

Winter Digging

This also improves the soil structure, although there is always a danger of damaging the roots of plants. This can be avoided by using a flat-tined potato-lifting fork, rather than a spade; the flat tines will keep each forkful more or less intact so that annual weeds can be turned in. At the same time any pieces of perennial weed which may appear can be picked out. Couch grass, ground elder, creeping cress, sorrel, thistle and the like are such nuisances that no effort Should be spared to get rid of even the tiniest piece, even if it means taking up a border plant to do so.

Before winter digging begins remove last year’s stalks. If you are not going to dig between the plants the dead stems may be cut back to ground level at any convenient time between November and February. This applies only to the truly herbaceous kinds, which lose each season’s growth above ground and start growing again in spring. However, any foliage, for example that of kniphofias, that remains green over winter should be left until new spring growth is about to begin and then it is a matter merely of tidying up the decaying or sere outer leaves.

Other Methods of Growing

For most people, a bed or border appeals as a well-defined feature in a garden. But hardy perennials may be grown in other ways. Many kinds can be grown in company with shrubs so that both are enhanced. Such erect and troublefree plants as hemerocallis flower from midsummer onwards to add more than a touch of colour to a background of shrubs. Apart from these, the wide range of ground-cover plants form a pleasing carpeting effect over what would otherwise be bare earth between shrubs, and most of these, too, will contribute colour.

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