Potatoes may be regarded as in a class by themselves. It should be remarked here that it does not pay most gardeners to cultivate main crop potatoes. They are so cheaply raised in fields, where machinery is used, that it is wiser for the home gardener to grow a little extra of the more valuable groups of vegetables, and to buy main crop potatoes for home consumption. Nevertheless, many gardeners prefer to raise all their own vegetables for the year, or prefer certain varieties of potato which are not easily obtained from farmers or from greengrocers.
POTATO CROPS GROW EASILY
Potatoes are a useful crop. They do not need rich soil, though some of the best crops have been raised in soil well manured with farmyard manure. I have seen potatoes set directly into fresh manure, dropped into an open trench, and the resulting crop has been all that could be desired. I have also seen good crops of potatoes grown on rather poor pasture land, where the grass has been turned in and the potatoes planted at the same time, and no additional manure or fertilizer given. Potatoes are frequently employed in this way to break and clean new land, and if they are hoed up once or twice during the season the soil is generally well cleaned by the time the potatoes are harvested.
In a great many home gardens it is not possible to use farmyard manure and an alternative must be found in fertilizers. Where prize crops are wanted, both manure and fertilizers may be used, and a good method to adopt is this. After double digging the spade is used to open a narrow trench, and manure is thrown all along the bottom of this, about 2 in. thick. The potatoes, which have been previously stood on end in boxes to sprout, should have one or two good strong shoots to each. If they have more, some of them should be rubbed away, as it is not advisable to plant potatoes with too many growing stems.
A good idea is to obtain potato seed early and set the tubers to sprout at once Tubers set in the sprouting boxes immediately after the previous season, and left in them all winter, make only a few stout growths in place of many weak ones. They must, of course, be kept entirely free from frost, but it is not necessary to exclude light. All that should be done is to set them rose end upwards in shallow trays. The rose end is the end where the eyes are clustered.
In planting, press the tuber into the soil, still with the rose end uppermost, and immediately draw over it about 4 in. of soil. Thus, it will be necessary to make the trench about 6 in. deep in the first place. Immediately afterwards, dust along the rows about three ounces to the yard of the following fertilizer : three parts kainit, two parts sulphate of ammonia and five parts superphosphate. This will ensure a good crop even from poor soil.
WHEN TO HOE AND SPRAY POTATOES
As soon as the tops of the early potatoes show through the soil, the first hoeing up should be done, i.e., a little of the soil from the sides should be drawn up over the tips that are showing. This prevents trouble from frosts, which can completely ruin the first early potatoes in a cold spring. All potatoes must be hoed up during growth, that is, the soil should be drawn up against the stems, leaving the potatoes apparently growing from the top of a ridge. This is done to cover the new potatoes, which tend to grow just at the surface of the soil. If they are not covered, they become green and are unfit for the table. Late potatoes, which make a smother of top growth that shades the ground surface, can sometimes remain without hoeing up, but generally speaking they too are better hoed.
Early potatoes do not require to be sprayed as they are seldom attacked by the potato blight, and are not intended for storing. Late varieties, which are to be stored during winter, must always be sprayed. ‘Potato blight is a very common disease, which turns the tops yellow prematurely. It prevents the proper development of the tubers, so that the crop is smaller than it should be. But it is even more harmful in another way. The disease travels down from the leaves to the tubers, and so affects them that they turn brown, and gradually decay into an offensive slimy mass of putrefying matter. Some of the tubers will show signs of the disease when they are lifted, but others may appear healthy at the time of storing. Later they may decay and the trouble will spread to healthy tubers stored with them.
Spraying with Bordeaux mixture or with Burgundy mixture while the potatoes are growing is the cure for this disease. Spraying should be done from the middle of June onwards at intervals of three weeks—two or three sprayings being desirable. The cultivator should never wait for the disease to appear, but should regard the spray as a preventive measure. Bordeaux and Burgundy mixtures are well known to horticultural sundriesmen, and can be purchased with instructions for use.
When sufficient potatoes are grown in the home garden to warrant storing, they can be packed into sacks, after being allowed to dry and being rubbed fairly clean of soil, and if the sacks stand in a frost proof shed, and light is not allowed to reach the tubers, they will keep well all winter, to be used as required. If sufficient room for such storage is not available, a clamp can be made in the open, as for other root crops such as carrots and parsnips. Choose the highest part of the plot for your clamp, or one end that can be spared for a few months. Lay the roots on to the soil over a layer of clean, dry straw or sand.
Then cover the potatoes with straw, making a sloping ridge or roof to the clamp Take a large digging fork and open a trench all round the clamp, packing the excavated soil solidly over the straw. Here and there along the top ridge a wisp of straw should be arranged to protrude, chimney fashion, so that the clamp is ventilated.