Deep Trenching.
Double Digging.—The deep trenching just described, in which the top soil was kept upon the top, and the subsoil underneath, is excellent where the subsoil is unfit for plant food, but there is a problem which it does not solve. Suppose we come to a garden matted hard upon the surface with buttercups, convolvulus, grass, twitch, groundsel, thistles and other tiresome weeds, then the last thing we desire is that these should remain on top. You cannot pull up the weeds by hand because the ground is so hard that you do no more than break the weeds, leaving the roots embedded firmly in the earth. Before there is any peace in the garden these weeds must be killed, and we will now describe how to do it. Suppose ABCD is the plot of ground. From AB measure four feet and draw the line EF. From ABFE take out the soil one spade deep, that is the top soil, and put it in a heap at G outside the plot. Now from ABFE take out the soil another spade deep, the subsoil, and put it in a heap at H. Now from EF measure two feet and draw the line IJ. Take the top soil, weeds and everything, from EFJI and throw it to ABKL—KL is two feet from AB—leaving KLFE empty for the present. Now take the subsoil from EFJI and throw it into ABKL, that is upon the top of the top soil you have just thrown there. Now measure another two feet from IJ and draw the line MN. The soil from IJNM will go into KLFE, top soil first and the subsoil on the top of it. Proceed in this way, two feet at a time, and when you come to CD throw the soil at G and H into the trench that will be left, top soil first and subsoil upon the top of it. The plot ABCD will now be well dug, and all the weeds will be deep under the soil where they will speedily die and decay; and even supposing that the subsoil you had brought to the top is not good, you may double dig again next year and so recover the old top soil minus the weeds. Any weeds that grow now may be eradicated easily from the loose soil, and even the weeds of twitch and convolvulus may be followed down and extracted. Unless you have unlimited time and patience to look after them do not be tempted to leave grass paths, but dig the garden from side to side. Grass paths are always spreading upon the garden and making the edges weedy and untidy. If you prefer it you may do this double digging with the plot divided as we divided it for deep trenching.
Double Digging.
How to sow Seed.—It is not wise to sow old seed. Even if they grow the plants are often without vigour. Go to a seedsman who has a good character and do not buy seed because its price is low.
The soil must be fine and firm, porous and moist. It must not be sticky nor dry. The seeds will not germinate until they can have both warmth and moisture. Sow thinly because crowded plants do not grow well. It is best to sow small flower seeds in pans and boxes well drained, as explained in our article on window-boxes to follow. Level the surface of the earth and make it firm. Water it with a fine spray and then stand it in the shade for about five hours. Now scatter the seed thinly and cover it very lightly with sifted earth. White-washed or paper shaded glass may be placed over the box or pan until the seeds appear. The glass will keep the air warm and moist. Except in the case of the very small seeds, the depth at which they are sown should be about three times their size or thickness.
In the garden do not sow broadcast, but in drills, as the ground can then be more easily weeded and kept loose when the seeds have grown.
After sowing press the soil well down and then water gently so that the seeds are not washed out, and the water drains away quickly.
The soil must not be allowed to get quite dry, and yet excessive moisture must be avoided. Too much watering is a common cause of failure.
If the soil becomes caked before the seedlings appear or patches be lifted by them, break it up with the point of a knife, and then water gently and just sufficiently to settle the soil round the plants.