This section is from the book "The Gardener V1", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
The past mild winter, cold biting March, and the warm weather we have experienced in April, have given us a "hint" not to put too much dependence in what may seem to tempt us to leave tender plants of any kind unprotected, as it is in changeable weather that mischief is generally done. After hot sunny days cold nights often follow. It is better to err on the safe side than run any risk. This is applicable to half-hardy plants, and also hardy ones which have been protected from severe weather. We have lately seen the thermometer standing at from 50° to 60° in the evening, and the following morning the ground in low-lying places has been quite stiff with frost. Vegetables - such as French Beans, Tomatoes, Potatoes, etc. - which have been brought forward under protection, must have that protection continued at night for some time to come. Some of the hardiest plants we have often seen killed by sudden exposure after being protected. As an example, we bought a great many dwarf common Yews to form a hedge. After they were planted, a severe frost, in March, set in and killed the most of them. A number of our own, taken from our exposed "storing-ground," and planted with the others at the same time, were left unscathed. So much for protected hardy shrubs, and vice versa.
It may thus be necessary to caution amateurs and others to ascertain in what position and other circumstances plants have been kept in nurseries before they take them to exposed positions for planting Of course, green healthy-looking plants are often the effects of injudicious protection. We have lately removed many thousands of the usual bedding plants from high temperatures under the shade of Vines, etc, and have not had any injury done to the most tender kinds. They are placed in sunk pits with boarded covers, which are removed by degrees till the plant will stand sun and air; but when wind is cold and biting, little air only is given, and that from the opposite side from where the wind comes. Glass, as a matter of course, would save much trouble and labour in such cases; but in its absence many makeshifts can be of tolerable service. When flower-pots or similar coverings are used for protection, they should stand clear of the leaves, otherwise they would be worse than useless. The main early crops of Scarlet Runners and French Beans may now be sown.
The former do well as a blind from anything unsightly, or in a row similar to Peas. However, they require good deep soil, otherwise they would seed prematurely and run themselves done; but by mulching, watering, and keeping the pods well picked off, they would keep on bearing all the season; but it is safe to have two or three successions. They may be planted 3 or 4 inches apart in the rows, and stake them before the wind destroys the foliage. They can be kept dwarf and in full bearing by topping them in. They thus form neat edgings to other crops. French Beans, being dwarf, are of little trouble, but the rows should be at least 2 feet apart. In Scotland or the colder parts of England this crop should be sown in the most sheltered parts of the garden, as in cold seasons they often do not come to much. Peas for succession should be sown at least twice or three times in the month; and if these are in properly-prepared ground, they will give pickings till frost takes them; this applies to Scotland. In England we always could sow a month later with success; but if watering, mulching, and the crop kept cleanly picked before the pods become old, are neglected, no other attention will secure success. Peas delight in deep well-cultivated soil, and the seed should not be too thickly sown.
Stake them in time, as the breaking at the necks of the plants causes premature fruiting. We top strong-growing kinds back, which causes them to break out and pod freely. Mildew is often the result of ground left untrenched, the roots going only to the hard bottom, and therefore cannot escape drought. The warmer soil and climate in the south give greater facilities for close cropping than in the north. Early and late crops are more easily secured, and more abundant supplies can be taken out of less ground, than in the north. Judicious manuring, winter trenching, etc, must in every case be carried out. Allowing change of crop is also of great importance. We make this an easy matter with Peas, as they are sown in single rows, dividing off other crops; and though in the same quarters of the garden every season, are seldom near the same place. Small successions frequently sown are necessary to keep up regular supplies of most things. We have seen in market-gardens near London three crops coming on at once in the same ground; and although we could in a great measure do the same in private gardens in England, we could not with any chance of success attempt the same in the north.
The practice is excellent where it can be carried out, as one crop is off and used up before the space is filled up by the other. The surface - soil should not be allowed to become baked over the roots of any vegetables, but the steel fork, hoe, itc, should be freely used. The loose surface acts as a mulching. Sow broad Beans for succession as formerly advised, and top the stalks when enough of flowers show for a crop. Let all early sowings of crops, especially roots, be looked over, and where failures have occurred, let them be made up without delay. Early Horn Carrot will come in quickly if the larger kinds have been destroyed. When the ground is stiff, lime may be freely dug in, which will help to destroy grubs, etc. We saw, the other day, this practice carried out with great success in an old garden where Carrots, Parsnips, etc, had failed for many years. Light ground would not be benefited in the same way by lime. Soakings of lime-water are of great service where grubs are destructive. Soot and guano dusted among growing crops in showery weather are useful agents for promoting free growth. Sow more Turnips, and thin any requiring it; for drawing young 6 inches apart will do, but for larger size 8 to 12 inches is not too much.