Greenhouse Management: Small Greenhouse and Conservatory
Small Greenhouse or Conservatory for Flower Growing
A small greenhouse is useful in that it can be used for raising bedding plants for spring and early summer planting and, also, provide pot plants for decoration in the home through much of the year.
The winter use of a greenhouse depends on whether it is heated, and if so, by what means. It is expensive to heat a house throughout the winter, solely to grow plants for pleasure. Often, if one growsin pots for November and December flowering, which entails heating, little further use may be made of the glass until propagation starts in February.
We have already touched on some of the main uses of a greenhouse, i.e. for pot plants, for raising bedding plants and for -growing in the autumn and early winter. As an alternative, some pot plants may be grown for October-December flowering. Often, the main summer use of a greenhouse is for tomatoes which do not enter into our flower survey here. To deal then in more detail with each of these main subjects:
Making use of the Greenhouse:
Growing Pot Plants
Some pot plants that are most easily grown in a small greenhouse can be found on post: “Potting Plants Successfully for Greenhouse Growing“. Many can be raised from seed, but if you have not had much previous experience of raising these subjects it is best to start with one or two, until confidence is gained.
Some helpful points of management where you have a collection of pot plants and other plants in a greenhouse are as follows:
General Attention to Plants in the Greenhouse
Where you have a batch of mixed plants, standing on a bench or staging, look them over about twice a week, if possible, and remove any dead leaves. Stir the surface of the, if it is very hard, and move the pots slightly about once a week to ensure balanced growth. Many plants in flower respond to better air circulation if they are stood on an empty inverted pot, of the same size. This not only shows off the flowers to best advantage but gives a better overall display.
In summer, and when plants are growing up to the flowering stage, most specimens respond to extra feeding. One of the best methods is to use liquid manure water. To obtain this, suspend a small bag full of manure in a tub or tank of water, and give it a “prod” every day. Use the liquid which results diluted to 10 parts of water, and feed the pot plants once a week with this in place of an ordinary watering.
Liquid manure not only contains most of the plant foods that are required but adds an extra “something” which gives better finish to the plants and improves the colour intensity of the flowers. Weak soot water can be given as a change, but bear in mind that this provides mostly nitrogen. It can be made in the same way as described for liquid manure.
Greenhouse watering causes more confusion than any other factor. For growing plants in spring and summer, more water is needed than in autumn or winter but, in either case, it is best to rely on tapping the pots daily (twice a day in hot weather) to ascertain the water requirement. Use the handle of a knife or a cotton reel on a wire handle. If the soil in the pot is dry, there will be a hollow, high-toned “ring” when the pot is tapped. If it is wet there will just be a dull “thud”. In this latter case do not water.
Water, either too much or too little, is probably the cause of many pot plants being checked or even killed. Over-watering is probably the most common fault, as the effects are not so quickly apparent as under-watering, where the plant “flags” or wilts.
The following points should be borne in mind for general guidance:
1. Do not just damp the surface. If the plant needs water, soak it, fill up the pot, let the water soak away, then water again. There must always be enough space left when potting to allow for watering. This may be an inch or more, depending on the size of pot.
2. To determine need for water, tap the pot with the knuckles or a wooden mallet – a cotton reel on a cane will suffice for medium-sized pots. If the pot really “rings”, it is on the dry side, if there is a dull “thud”, it is wet. With large pots the difference in weight between a dry plant and a wet one is worth checking.
3. Where there is a batch of pot plants, in practice one finds that perhaps a third are dry and need water, a third are really wet, needing none, and the other third will probably need checking over again later in the day.
4. In warm sunny weather it is best to look over the plants two or even three times a day.
5. The colour of the soil may, with practice, denote need for water or otherwise, but do not be misguided by the state of the top layer; it may be dry, yet the remainder of the ball of soil not in need of water.
6. If one person does the watering, it is easier than if others do it as well. You will get to know the plants and their individual requirements.
7. Weather can affect considerably the amount of water required. Tap each one if in doubt. Dull weather means less watering. Keep plants on the dry side in winter, rather than overdo the application.
8. Do not wash the soil out of the pot in watering. Use a small spout attachment on the can if it is too large, or plug the end with a piece of wood.
9. If using a hose pipe adjust the pressure according to requirements.
10. For small numbers of pots, stand a really dry plant in a bowl or bath of water and let it soak up all it needs.
11. Do not top dress or feed a dry plant, or the mixture may be too rich and damage to roots result.
12. Incorporate liquid manure in watering every 10 days or so, where necessary, to plants in growth and coming up to flower.
13. Do not be misled by a storm of rain in pots of, for example, chrysanthemums out of doors in summer. The leaves and the plants themselves shield much of the soil from rain and on checking the pots, many will often be found really dry.
14. It is impossible in general notes of this sort to deal with the watering ofand plants that are being dried off. The above remarks are intended as a general guide to the treatment of the average pot plants grown, for those who have not had many pot plants before.
15. Finally, above all, do not water indiscriminately; do not water all the plants at once and water only if needed – then water well.
A good, general-purpose potting mixture can be made from mature, well-made, passed through a 1/8 in. sieve, plus coarse sand, peat and loam. The proportions can be 2 parts compost, 2 parts loam and 1 part each of peat and coarse sand. Make sure that the latter is coarse, as the drainage benefit it gives to the mixture is most important.
If loam (the result of turf being stacked for 6 months or so) is unobtainable, the alternative is to use the best garden soil available. In any case, to each bucketful of potting mixture add a handful each of bone meal, hoof and horn and wood ash.
Pest Control in the Greenhouse
There are several pests that may attack plants under glass and, under warm summer conditions especially, pests can increase very quickly. The best insurance against attack is a good growing medium combined with good management.
One of the most common pests is White Fly, especially onand . As a last resort and as an expedient, fumigation with D.D.T. or B.H.C. smoke cartridges may have to be done. Make sure that the cartridge or cannister used is the right size for the cubic capacity of the house (length by breadth by average height).
Either of the fumigants mentioned will kill aphids but spraying can also be done against this latter pest. Avoid such poisonous substances whenever possible, however by correct treatment and management this will result in healthy growth.