This section is from the book "The Gardener V2", 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.
Continue to apply the directions of last month to those that are starting, and that have shown their fruit distinctly. The most important point in their management this month is to keep the soil about their roots moderately moist, especially avoiding a state of mealy dryness at any time - a condition which, now that the sun has more power, and that air has to be more liberally admitted, will check and stunt the young fruit. With increased light, the temperature may safely be advanced to 70° at night, and to 85° for a short time at shutting-up time, with sun heat; more moisture in the air is also necessary as light and heat increase. When the fruit are done flowering, give a very light dewing overhead with tepid water through a very fine rose. Where there are any Pines that are farther advanced, and which it is a desideratum to ripen early, these may now be pushed on with a few degrees more heat than is named above, especially when shut up with sun on fine afternoons. Very hard forcing, requiring highly - heated pipes during cold parching winds, should be avoided, and the milder weather as it occurs should be taken advantage of for pushing them rapidly on.
Colour the water with Peruvian guano for every watering, and pour a little of it into the steaming-troughs. Later-fruiting stock, that are intended first to make a growth and then start, should now be kept moderately and steadily moist at the root, and air moisture increased in proportion with a temperature of 65° at night, so as to encourage a healthy growth, and prevent any checks that are calculated to cause them to show fruit prematurely. These, after making a growth, generally yield the finest fruit of the season. Generally speaking, this is the month when the majority of autumn - potted suckers require to be shifted into their fruiting-pots. But we have an aversion to fixing times and seasons to a week, or even a month. If the suckers show plenty of young healthy roots round the sides of the balls, they are ready to shift. If they are not in this condition, and the soil is in a proper state, leave them till they are. If the soil is at all wet and pasty, and roots scarce, the sooner they are shaken out of such soil and potted in proper soil the better.
On the other hand, if they are what is known, in garden phraseology, matted or pot-bound, then they should have been shifted last month; and the chances are, that instead of starting into growth when shifted, they will start into fruit. To run the least risk of this, we advise their being entirely "shaken out," preserving the roots as much as possible, and pot them firmly at once into their fruiting-pots, using moderately - moist soil, and watering them sooner after being potted than would otherwise be advisable, and give more atmospheric moisture. By such treatment, any of them that are to start prematurely into fruit will do so at once, and then they can be got rid of. Our own practice is to shift - any time - into pots a size larger in October, November, December, or January, rather than run the risk of a matted ball and stunted plant that is worthless after being wintered. For Queens, we consider 11-inch pots sufficiently large. For Cayennes, Charlotte Rothschild, and other large-growing sorts, we would not exceed a 12-inch pot. We have experimented on this point, and found that 11 and 12 inch pots gave better returns than larger sizes. These sizes will produce Queens from 5 to 6 lb., and Cayennes from 8 to 11 lb., weights sufficient to satisfy any requirements.
Crock with ½ - inch crocks to the depth of 1½ inch, and cover the crocks with a thin even layer of the fibre from the loam, and then dust with a little fresh soot to keep worms at bay. We consider a brown hazelly loam, neither very light nor very heavy, taken to the depth of 4 inches from old pasture, and stacked ten or twelve months in a dry place, the best for Pine-culture. To this we do not recommend anything to be added, beyond an 8-inch pot full of ½-inch bones or bone-meal, and an equal quantity of soot to every two barrow-loads of loam, the whole being thoroughly mixed together. Strip off a few of the bottom leaves, rub the inert soil from the upper part of the ball, remove the old crocks, and disentangle slightly the roots. In potting, ram the soil firmly with pieces of wood made for the purpose. In plunging them in their growing quarters, avoid crowding. Queens should not be closer than 22 inches each way, and larger sorts 24 inches. The bottom - heat should range from 80° to 85°, not higher. Avoid shading much after shifting, unless the weather be very bright, and then only shade for two hours in the middle of the day.
During cold March weather, 65° is heat sufficient for a maximum at night; when mild it may range to 70° till 10 p.m., but allow it to sink 5° before daylight. Give air in moderate quantity for the first fourteen days after shifting; afterwards increase it, as the plants begin to grow more freely. Avoid in all Pine-houses cold draughts as much as possible.