This section is from the book "The Gardener V3", 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.
Very early plants will come into bloom this month, and if much fire-heat is used, they will not set well. 50° in cold, and 55° in mild nights, ought not to be exceeded. Do not expose the blossoms to currents of cold air; and if necessary, fix some hexagon netting or perforated zinc over the ventilating openings to prevent such. Do not stand plants in saucers of water; and if anything be placed under them, let it be cocoa - nut fibre or a thin strip of turf. When set, raise the temperature 5°, and run up the house to 75° with sun-heat at shutting-up time. Introduce more plants into heat. Peach-houses shut up for forcing are good places for them, if there is not the convenience of a pit or house that can be devoted exclusively to Strawberries.
In mild weather those which have set their fruit may have the temperature increased to 60° in cold and 65° in mild nights. They will also require a more plentiful supply of water, and must never be allowed to get too dry. Plants in bloom should not have more heat at night than 55° until set. Continue to introduce succession lots of plants fortnightly, according to the accommodation for forcing and the stock of plants.
Thin off all blind blooms and small fruits from the trusses of those that are well set. As the days get brighter more water is necessary, and they must never be allowed to suffer for want of it. A good plan is to fill pots half full of soil and place the Strawberry-pots in them; they root freely into the soil, and the pot shades the roots from the sun. The night temperature for fruit should be 65°. Plants in bloom set best at 55°, with a little air on all night. Put more plants into heat, according to the stock and room. By the end of the month place all the store stock in cold pots or orchard-houses, to be coming on gradually before being placed in warmer quarters.
Remove to cold frames all plants from which the fruit is all gathered, to be thoroughly hardened off' before being planted out. Subject colouring fruit to a free circulation of dry warm air. Thin the fruit from the trusses of those which are beginning to swell: a temperature of 65° at night is high enough for those swelling off. Those in bloom set better at a temperature of from 55° to 60°. After this season it is a good plan to stand the pots of plants in all stages in pots of the same size, half filled with equal portions of loam and rotten dung. Introduce more plants into heat, and put all remaining stock in cold pits or frames, where they will now grow freely by the aid of husbanded sun-heat.
Plants swelling off heavy crops of fruit will now require careful attention in watering, and if standing on shelves will require to be watered twice a - day. But all Strawberries in pits should at this season be set on a cool, damp bottom, if not in pots or saucers filled with rich soil. Red - spider is apt to be troublesome now, and the syringe should be freely used up to the time the fruit begins to colour. Fruit ripened now in airy houses are generally of excellent flavour. All plants that have been forced should be well hardened off and planted out in rich soil for fruiting next year.
Those now ripening their crop will do better in a cold pit with sun-heat than on shelves in forcing - houses. They will want copious supplies of water and plenty of air when colouring. Plant out all plants from which the crop is gathered on rich and deeply - worked ground. Immediately runners can be had for layering, get the necessary stock for next year's forcing layered either in 3-inch pots in rich soil, or place the soil between the Poses and lay the plants on it. For early forcing, the plants should be shifted into their fruiting-pits early in July.
See last month's Calendar. All plants should be in their fruiting-pots by the middle of July at the latest. In potting them, let it be done firmly, using a rather strong fresh loam with about a third of well-decomposed dry cow or horse manure and a little fine bone-meal. In placing them to make their growth, choose an open warm position, placing them on something that will prevent worms from getting into the pots. Give them plenty of room, and never allow them to suffer for want of water.
These, if shifted into their fruiting-pots last month, and have been managed as directed in last month's calendar, will grow with great rapidity and vigour this month if it be bright and warm, and will require to be liberally supplied with water and occasional waterings of liquid manure. If they are crowded in any way, thin them out and give them more room, so that they get plenty of light and air about their leaves. They may be sprinkled overhead about five o'clock on the afternoons of warm days. Keep them clear of weeds and runners.
See last month's directions. If the weather should be bright and dry, they will require good supplies of water. Where plants are making more than one or two crowns, remove the weakest. Keep them free from runners and weeds, and give them plenty of standing room.
If former directions have been carried out, these should now have their pots thoroughly rilled with roots, and have large well-developed crowns. But the season having; been most unfavourable for the production of fine plants, it may, in many localities, be desirable to place at least some portion of the stock in cold pits or frames, where they can be kept near the glass and have plenty of air. This would materially assist late plants in maturing their growth. Remove all runners as soon as they show themselves.
 
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