How to Force Vegetable Plants
‘Forcing’ the Pace of Growth
Another way of beating the seasons is by forcing plants, that is, creating slightly warmer conditions so that they come into growth a little sooner. In the old days, it was done extensively with hot beds of fermenting stable manure — not a practical proposition for most modern gardens. Simple alternative methods are available, either by leaving the plants outdoors, or by lifting them and bringing them into slightly warmer conditions in greenhouses, sheds or in the house.
Forcing is often coupled with blanching, which means excluding light and so making plants white, tender and sweeter. Traditionally, many of the more bitter salad plants such as endives, dandelion andwere blanched.
Blanch endives and dandelions a few at a time as they may rot if not used soon after being blanched. Choose a dry day, or cover the plants beforehand with cloches to dry them off. Remove any dead or decayed leaves. Bunch up the leaves, and tie them towards the top with a piece of raffia, then cover the plants with a large flower pot with the holes blocked to exclude all light. The plants should be blanched within about fifteen days.
The ‘chicons’ of Witloof, the weather-resistant Belgian chicory, are easily produced at home, even if they look less elegant than shop-bought chicory. The chicory is sown in May or June and the plants thinned to about 15cm (6in) apart. They look like untidy dandelions.
In late October or November lift the roots. Reject any very thin or fanged roots, and trim the leaves off about 2.5cm (1in) above the root. If they are not required for immediate forcing (and it is best just to do a few at a time to keep a constant supply), store them horizontally in boxes of moist peat or sand in a dry shed.
Then, beginning in November, plant two or three roots close together, in ordinary, in a large 20-23cm (8-9in) flower pot or similar container. Cover the pot with an inverted pot of the same size, with the drainage hole blocked to exclude light. Bring the pot indoors. The temperature need be no higher than 10°C (50°F), though growth will be faster at higher temperatures. Keep the soil moist. The chicons should form within about three weeks. Keep the cut chicons in the fridge when they are ready, as they will become green and bitter on exposure to light. A secondary crop of smaller leaves may be produced by the stump if it is left in the pot.
How to Force Rhubarb
Outdoors: Pack straw or dead leaves around the crowns in December or January, then cover them with upturned boxes, tea chests, ash buckets or traditional pots. The stems will shoot up earlier and be exceptionally pink, sweet and tender.
Indoors: Dig up the plants in late autumn. If there has been no frost, leave them on the ground until after a period of cold weather to break their natural dormancy. Then plant the crowns under the staging in a greenhouse, or in large pots or boxes which can be brought indoors. Cover them with a similar container to exclude light if you want the stems blanched. The leaf stalks start to grow at temperatures of 7-16°C (45-61°F). Rhubarb can also be forced in black plastic sacks. The ideal temperature is 13°C (55°F): at higher temperatures the sticks are paler, and at lower temperatures development is slower.
How to Force Seakale
Outdoors: Force as for rhubarb, but cover with something that will allow the plants to grow up to 45cm (18in) high. Oldpots, of course, were designed for the purpose. The shoots will be ready between March and May, and have a wonderful texture and taste.
Indoors: Use plants at least two years old. Lift them in November, trim off side roots, and pot them up close together in boxes, pots, or a darkened area under the greenhouse staging. All light must be excluded to get the best flavoured shoots. The temperature for forcing should be 13-16°C (55-61°F). Forced plants have to be discarded after use.