Handpicking of perennial weeds is useful, but more certain results can be obtained by using a weedkiller containing glyphosate. This is a translocated weedkiller which is absorbed by the foliage of the weed and then transmitted throughout the sap stream, kill­ing the plant entirely but not polluting the soil. Early spring is the ideal time to make an application, just as the plants are begin­ning to shoot, for the chemical is more readily absorbed and translocated at this time. Spraying in spring usually catches any pieces of root missed during handpicking as these will also be producing small shoots.

There is not a lot of difference between planting a new border and refurbishing an existing one. An existing border will doubt­less contain a number of plants that resent disturbance, or in the mixed border there will doubtless be shrubs that must be worked around. Some herbaceous subjects resent disturbance so much that they sulk and refuse to flower for several years after being moved plants like paeony and Christmas rose as well as any members of the pea family, such as Russell lupins. These must all remain where they are, unless they are exhausted, when plants like lupins can be increased by cuttings of young shoots taken as they emerge from the crown in early spring.

Once soil preparation is completed, the areas which various groups of plants are going to occupy can be marked out with sand. It is useful to have an idea of where you are going to put each plant variety and I find a rough sketch on paper a useful guide. Do not be hide-bound by your original ideas as these were in all probability made at the kitchen table and imagination and reality do not always tie up. Use the sketch as a basis upon which to work. Do not be so dogmatic that you have no flexibility. As long as certain basic principles are adhered to there is little that can go wrong in the planning of a mixed or herbaceous border. The arrange­ment of colour and Contrast is purely per­sonal, so are shapes and heights, and their combinations. What is not flexible is the quantity of plants necessary to create a satis­factory effect. Single plants do not create an attractive picture, nor in a cottage garden context do square, circular or oblong blocks of plants. Do what you wish about colours and contrasts, but stick to groups of five, seven or nine plants and arrange them in an irregular fashion.

To improve light soils, moisture-holding materials such as cow or pig manure, or old leaves and compost, should be incorporated. Artificial fertilizer should only be used dur­ing the active growing season, for if applied during winter the rain will almost certainly wash it out of the soil before it has an opportunity to work. Regular hoeing during the summer assists with retaining moisture, while surface mulches of old leaves or rotted lawn mowings around individual plants are most beneficial.

Heavy soils, conversely, require lighten­ing and opening up. This can be done by digging in quantities of straw, strawy manure, sand, grit, clinker or indeed any other material of a coarse texture. On clay soils with a relatively low alkalinity, hyd-rated lime can be used. When spread evenly over the soil surface and then lightly raked in it causes flocculation of the clay particles – the collecting and separating of colonies of tiny particles which under the physical influence of the lime form larger particles, which in turn makes the soil lighter.

Soils of many varying textures and consti­tuents exist, such as peaty, alluvial, marl, and others too numerous to consider, but all can be classified with some degree of accur­acy under the heading of light or heavy. However, apart from visible physical char­acteristics there are those unseen, particu­larly acidity and alkalinity, which are of equal importance but more difficult to ascertain. A pH test – obtainable in kit form from the local garden shop – has to be employed to determine the acidity or alkali­nity of the soil. The theory and reasoning behind this is complex and irrelevant at this stage, but it is sufficient to say that a pH of 7.0 indicates a neutral soil, one higher, say of 8.0 alkaline, and those of lower numerals acid. Careful observation of local wild flowers will also yield much information.

Where heather, foxgloves and sorrel flour­ish the soil is invariably acid, but where vetches, cranesbills and old man’s beard thrive then it will almost certainly be alka­line. These conditions can have a marked effect upon plant growth; where such con­ditions may pertain.

Soil is a living material. If healthy it contains billions of micro-organisms which live off the organic content which mainly consists of decaying vegetation. Good soil must also contain moisture and oxygen, and usually carries a high proportion of mineral particles. When very fine, the soil resembles clay; when coarse, a sandy loam. On fen- and peatland the topsoil may be composed almost entirely of organic material, the result of millennia of sedges or mosses living and dying, gradually forming a thick layer of fibrous material.

Most gardeners need only know whether their soil is clay-like or sandy. Clay retains moisture, is difficult to work and sticky when wet, and sets very hard with surface cracks in a dry summer. It needs regular breaking up over winter with a soil conditionier (for example, mushroom compost), although it is often very fertile in its own right. Sandy soil is easy to work and dries out quickly, but needs plenty of well-rotted manure or compost to improve moisture retention. Alluvial silt in a flood plain is an exception to the sandy rule; it is easy to work, fertile, and though free-draining, excellent at retaining moisture.

Acidity and Alkalinity

Plants manufacture their own food by converting carbon dioxide in the atmosphere into carbohydrates. Other essential ingredients come from mineral salts dissolved in the water that coats the soil particles. Nitrogen, phosphorus and potassium are needed in fairly large quantities, with minor but vital additions of magnesium, calcium, sulphur, oxygen, iron, manganese, boron, molybdenum, copper and zinc.

Plants differ in their ability to take up these mineral nutrients. Some are only efficient at absorbing iron, for example, in acid soil. Others can obtain everything they need even in the most alkaline conditions. That is why it is essential to know the character of your soil. If it is alkaline you will not be able to grow limehaters such as rhododendrons or camellias. In very acid soils limestone plants such as philadelphus, clematis and dianthus will flounder. You can easily buy cheap pH testing kits which you should apply to different parts of the garden since conditions will vary. (The pH refers to the negative decimal logarithm of hydrogen ion concentration expressed in moles per litre). A pH of 7 is neutral; anything higher, and the scale goes up to 14, is alkaline, and anything lower acid. Generally, most plants thrive at 6.4-7, vegetables preferring 7-7.5. To confirm your readings look around the neighbourhood to see what plants are growing well in other people’s gardens. If you want to increase soil alkalinity add lime. But note such a step tends to be irrevocable so think carefully before you act. It is not so easy to increase the acidity. The best way is to create raised beds, or special enclosures, filled with acid soil for ericaceous plants.