FORCING STRAWBERRIES UNDER GLASS
Trained gardeners need no instruction from me on this topic. There may
be those, however, who have never given the subject attention, and who
would be glad to learn some of the first principles of success in
forcing this fruit for market; while a still larger number, having
small conservatories and warm south windows, would be pleased to see a
few strawberries blossoming and ripening, as an earnest of the coming
June. There are no greater difficulties in the way than in having
flowers, for it is merely a question of doing the right thing at the
right time. I do not believe in a system of minute, arbitrary
directions, so much as in the clear statement of a few general
principles that will suggest what ought to be done. The strawberry
plant has the same character indoors as out, and this fact alone, in
view of what has been written, should suggest moisture, coolness,
light, and air. I shall endeavor to present, however, each successive
step.
First, prepare a compost of thoroughly rotted sods and the cleanings of
the cow-stable, in the proportion of three parts sod-mould to one of
manure. In the place of sods, decayed leaves, muck, sweetened by a
year's exposure to air and frost, or any good, rich loam will answer.
With this compost, made fine and clean by passing it through a coarse
sieve, fill in June, and not later than July, as many three-inch pots
as you desire; then sink them to their rims along the sides of the rows
from which you propose to obtain winter-bearing plants. Varieties best
adapted for forcing are those of a low, stocky growth, bearing perfect
flowers and sweet or high-flavored berries. I should say the Triomphe
de Gand was the best, and I observe that it and the La Constante, which
it closely resembles, are highly recommended abroad. The bush Alpines
are said to do finely, and I should think the Black Defiance would
answer well. Mr. Henderson speaks highly of the Champion, which,
however, must be grown with a perfect-flowered kind, since it is a
pistillate. From the parent row, guide the first runners so that they
will take root in the pots. Let each runner form but a single, strong
plant, which it will do in about two weeks, filling the pot with roots.
Then these plants, with their accompanying balls of earth interlaced
with roots, are ready to be shifted into pots of from six to eight
inches in diameter, which also should be filled with the compost
already described.
These larger pots should have three or four pieces of broken pottery in
the bottom for drainage. One plant to each pot is sufficient, and the
soil should be pressed firmly about the roots. The methods of growers
now differ somewhat, but all agree in seeking to promote a continuous
and healthy growth. It may be necessary to place the pots in a
half-shady position for a few days, till the effects of shifting are
over, and the roots have taken hold of the new soil. Then they should
stand in an open, airy position, close together, where they can receive
daily attention. Some recommend that they stand on boards, flagging, or
bricks, or a layer of coal ashes, since earth-worms are thus kept out;
others sink them in cold frames, where they can be protected somewhat
from excessive heat and drenching storms; while others, still, sink the
pots in the open ground, where it is convenient to care for and water
them. It is obvious that moisture must be steadily and continuously
maintained, and the plants be made to do their best until about the
first of October. After this, they should be watered very
sparingly--barely kept moist--since it is now our aim to ripen the
foliage and roots and induce a season of rest. At the same time, they
should not be permitted to dry out. About the first of November, an old
hot-bed pit can be filled with dry leaves and the pots plunged in them,
close together, up to their rims, and, as the season grows colder, the
tops can be covered, so as to prevent the earth in the pots from
freezing. The top of the pit can be covered with boards to keep out the
wet, but not so tightly as to exclude the air. Our aim is to keep the
plants dormant, and yet a little above freezing, and barely moist
enough to prevent the slightest shrivelling. Since it requires from ten
to fourteen weeks to mature the fruit under glass, it would be well to
subject some of the plants to heat early in October, so as to have ripe
berries at the holidays. They can thereafter be taken from the storage
place every two or three weeks, so as to secure a succession. By this
course, also, if a mishap befalls one lot of plants, there still remain
several chances for winter fruit.
In the forcing process, follow nature. The plants do not start suddenly
in spring, but gradually awaken into life. The weather, also, is
comparatively cool when they are blossoming. If these hints are not
taken in the green-house, there may be much promise but little fruit.
If the heat is turned on too rapidly when the plants begin to bloom,
the calyx and corolla will probably develop properly, but the stamens
will be destitute of pollen, while the pistils, the most complicated
part of the flower, and that which requires the longest time for
perfect formation, become "a mere tuft of abortions, incapable of
quickening, and shrivelling into pitch-black threads as soon as fully
in contact with the air." Let the conditions within-doors accord as far
as possible with those under the open sky. The roots require coolness,
continuous and evenly maintained moisture. One check from over-dryness
may cause serious and lasting injury. The foliage needs air and light
in abundance. Therefore the pots should be on shelves close to the
glass; otherwise the leaf and fruit stalks will be drawn and spindling.
If the pot can be shaded while the plant is in full light, all the
better. When first introduced, the temperature should not exceed 45
degrees or 50 degrees. Air must be freely admitted at all times, though
much less will suffice, of course, in cold than in warm weather. Watch
the foliage, and if it begins to grow long and without substance, give
more air and less heat. An average of 55 degrees to 70 degrees by day
may be allowed, and from 45 degrees to 50 degrees by night.
When the flower buds begin to open, the forcing must be conducted more
slowly and evenly, so as to give the delicate organs time to perfect;
but after the fruit is set, the heat can be increased till it
occasionally reaches 75 degrees at midday. After the fruit begins to
color, give less water--barely sufficient to prevent any check in
growth, and the fruit will be sweeter and ripen faster. The upper
blossoms may be pinched off, so as to throw the whole strength of the
plant into the lower berries. Keep off all runners; syringe the plants
if infested with the red spider, and if the aphis appears, fumigate him
with tobacco.
The plants that have fruited need not be thrown away as useless. If
they are turned out of the pots into rich, moist soil, in April, and
the runners are kept off all summer, they will make large, bushy
stools, which will give a fine crop in autumn.
The amateur, with a small conservatory or south window, by
approximating as far as possible to the conditions named, can achieve a
fair success. I have had plants do moderately well by merely digging
them from the beds late in the fall, with considerable rich earth
clinging to their roots, and then potting with more rich soil, and
forcing them at once. Of course, fine results cannot be expected from
such careless work, but _some_ strawberries can be raised with very
little trouble. If one, however, wished to go into the business on a
large and scientific scale, I would recommend a straw berry-house,
designed by Mr. William Ingram, gardener at Belvoir Castle. A figure of
the structure may be seen on page 74 in Mr. Fuller's valuable work,
"The Small Fruit Culturist." On the same principles that we have been
describing, the ripening of strawberries can be hastened by the use of
hot beds, cold frames, and ordinary sash.
During the Christmas holidays strawberries sell readily at from $4 to
$8 per quart, and handsome fruit brings high prices till March; but the
profit of raising them under glass threatens to diminish in future
years, since Florida berries begin to arrive freely even in February.
There are those who now seem to be doing well in the business of
forcing, if we may judge from the jealousy with which they guard the
open secrets of their calling from their neighbors.
A rough and ready method of forcing is to dig up clumps of plants
during a mild spell in winter or early spring, put them in boxes or
pots of rich earth, and take them into the green-house. Considerable
fruit is sometimes ripened in this way.
An English writer says: "We find forced strawberries mentioned as being
served at an installation dinner, April 23d, 1667; but the idea had
already occurred to the great Lord Bacon, who writes, 'As we have
housed the exotics of hot countries, so we may house our natives to
forward them, and thus have violets, strawberries, and pease all
winter.'"