season advances the trenches must be less deep.

==Earthing up== is often performed in a rough way, as though the plant
were made of wood instead of the most delicate tissue. The first
earthing should be done with a hand-fork, and quite loosely, to allow
the heart of the plant room to expand. The result should be a little
ring of light earth scarcely pressing the outside leaves, and leaving
the whole plant as free as it was before. A fortnight or so later the
earthing must be carried a stage further by means of the spade. Chop the
earth over, and lay it in heaps on each side of the plant. Then gather a
plant together with both hands, liberate one hand, and with it bring the
earth to the plant half round the base, and, changing hands, pack up the
earth on the other side. Be careful not to press the soil very close;
also avoid putting any crumbs into the heart of the plant; and do not
earth higher than the base of the leaves. As soon as may be necessary
repeat this process, carrying the earth a stage higher; and about a week
from this finish the operation.

The top of the plant must now be closed, and the earth carefully packed
so high that only the very tops of the leaves are visible. Finish to a
proper slope with the spade, but do not press the plants unduly, the
object being simply to obtain a final growth of the innermost leaves in
darkness, but otherwise free from restraint.

==The Bed System== answers particularly well for producing a large supply
of Celery with the least amount of labour. This method of cultivation is
also especially suitable for raising Celery intended to be served when
boiled, or for soups. Celery beds are made four and a half feet wide and
ten inches deep, the soil which is taken out being laid up in a slope
round the outside of the bed, and the bank thus formed may be planted