To check the draining qualities of your soil, dig 12in to 15in deep holes here and there. Water shouldn’t stay in them for more than a day, after a wet spell.
If it does, drainage is needed. Easy-to-lay, continuous lengths of plastic drainage pipe usually serve the purpose.
Where it is not possible to easily improve drainage, consider building up beds 9in or so above the general soil level. Timber, precast masonry, or natural-form rockeries can be used to retain these elevated beds.
Merely to excavate paths between the beds raises their level. These paths must be graded so that they carry off the water, not trap it.
Heavy soils can be kept in the crumbly condition needed for good root growth by occasionally adding compost, well-rotted horse or cow manure, leafmould, or other fibrous organic materials – substances that support the growth of beneficial organisms that abound in healthy soil.
Whether compost and other organic material should be dug into the soil or not depends on how decomposed it is. If sufficiently decomposed to have lost its fibrous nature, did it in; but if not leave it as a surface mulch, which feeds the soil as it decomposes.
Mulch also insulates against excessive temperatures, conserves moisture, and protects clayey loams from puddling during heavy rain and watering. In sandy soil, it helps to retain valuable humus and semi decomposed organic particles.
Once the soil has been made into a good crumbly loam you can keep it that way if you don’t disturb it while wet or sticky. If you do, it sets as a hard mass.
So do not dig, weed, plant, or (if possible) walk on soil that is wet.
As a test, take a handful and mold it into a ball. To be ideal for digging or planting, the ball should be just damp enough to hold its shape but dry enough to shatter or crumble on impact. If it doesn’t or is still obviously sticky, leave for another day and try again.
Sandy soils can be safely worked at any time, but drain so rapidly that they dry out too quickly and plant foods wash through them. Some are so fine that the particles pack too closely, and water or air do not penetrate easily.
Adding peat moss and any of the organic materials suggested for heavier soils will improve the texture and sandy soil’s ability to hold food and water.
Heavy clay. Soils that contain a lot of clay become very sticky when wet, or hard and rather unyielding when dry. Their condition improves permanently if you spread a couple of inches of coarse sand and work it in, 4 to 5in deep.
This needs to be done when the soil is in a just-damp state – as it would be if well watered a few days beforehand. A rotary hoe makes light work of the job in large areas.
Sawdust is also an excellent lightener for heavy soils, mixed in like the sand, or in conjunction with it. It won’t retard plant growth if a complete fertilizer or fowl manure is added to compensate for the nitrogen it borrows, decomposing.
You can plant a few weeks after this is added, but if initial growth appears slow occasionally use one of the water-soluble plant foods.
Another way to break up clayey soils is to thickly sow wheat, a handful to the square yard and about twice this amount of fertilizer.
The wheat’s fibrous roots penetrate the damp soil, creating a more crumbly, fibrous texture. This green crop is chopped in when about 10in high. Planting can begin five or six weeks later.
Lime. Lime does improve heavy soils by causing finely dispersed clay particles to flocculate or group together, giving the soil a more crumb-like texture. However, over-liming can be harmful, as it renders some plant foods insoluble, and deficiency symptoms occur.
Iron is one element that quickly becomes insoluble in over-limed soils, a deficiency which shows as a yellowing of new growth. (Yellowing from most other causes shows more on the lower or older foliage.)
Garden lime, agricultural lime, or dolomite can be used safely with fertilizers or at planting out or sowing time.
Peas, beans, cabbages, onions, carnations, and most annual flowers appreciate a neutral or moderately limy soil; but azaleas, rhododendrons, ericas, Japanese irises, most lilies, parsley, and radishes prefer acid soils and resent lime.
If doubtful about whether your soil is acid or alkaline (limy), get a pH indicator. This consists of color-indicator liquids, which change according to the acidity of the soil sample, and an indicator chart.
Hydrangeas give an indication of soil acidity. Bushes produce mainly blue flowers if the soil is acid, pink if limy or alkaline.
Feeding plants. As mentioned, compost is an excellent plant food and soil improver, but the balance of plant food it contains is related to the state of the soil its components were grown in. Similarly, animal manures vary.
When planting out or sowing flowers and vegetables, results are improved by adding a complete fertilizer, as most of these contain a balance of plant foods.
Just mix these preparations into the soil by raking lightly back and forth. Rain or watering soon carries the nutrients down.
Complete fertilizers such as bone dust and cottonseed meal supply plant food gradually as the organic materials decompose, so can be applied more liberally than most chemical fertilizers.
Beware of overfeeding, which damages the plant’s roots and can result in starvation. Don’t exceed the amount recommended on the package, and keep the soil reasonably moist for at least a week after feeding.
Also, feed only when the soil is evenly moist, so that soluble chemical salts diffuse evenly and don’t cause root burn.
Soluble plant foods offer convenient, relatively safe feeding. They are a good follow up to complete fertilizers applied near planting time and supply the extra nitrogen annuals need at bud stages, and needed by leafy vegetable crops.
For azaleas, camellias, orchids, and most shrubs, they do the most good in spring or summer, when growth is active.