Sowing Brussels Sprouts Seeds
Brussels sprouts can be sown in a seed-box, in boxes under cloches or outdoors in a seed-bed and then transplanted to their final positions. Transplanting seems to strengthen the plants and gives an improved crop.
Any available plot of fairly finewill do for a seed-bed, as the plants will only be there for a few weeks. Rake the soil over lightly, and make drills about 1.5 cm (1/2”) deep, and 15-23 cm (6-9”) apart. For a maincrop of sprouts, sow the seed in mid-spring. Like all brassica seed, that of Brussels sprouts is small and round; sow them quite thinly. Germination should take place within seven to twelve days of sowing, a little longer if the weather is cold. If you have any seed left over, keep it, as it will remain viable for three years.
For sowing in containers, choose standard-sized seed trays or pots filled with a good quality seed. Sow as you would for seeds in the open ground, and keep the containers indoors or in an unheated greenhouse.
You can also make sowings in frames or under cloches. Again, follow the instructions for sowing in the open ground. For frame cultivation, water the soil thoroughly before sowing, if it is not already moist, so that further watering is unnecessary during the seedling stage. If sown under frames or cloches, the plants can be thinned and then left in their original positions to mature if you do not wish to transplant them, but remember that the plants may not be as good in the long run. If the seed is sown outdoors without any protection with glass or plastic, cover with netting at once; birds, especially pigeons and sparrows, are very fond of the plants, both when young and mature.
Another alternative, if you do not wish to take the time and trouble to sow seed and grow, is to buy plants at the transplanting stage. There are always plenty of Brussels sprout plants available at markets and garden shops in late spring. A delay of a day or two between pulling the plants and replanting them should not cause too much harm.
As a general rule, young Brussels sprout plants should remain in the seed-bed, without pricking out, until ready for transplanting. They will need thinning, probably twice, so that they are spaced about 10 cm (4”) apart before moving.
Some gardeners transplant most of the crop, but leave a few plants where they were sown, spaced about 45 cm (l-1/2”) apart. This can be satisfactory, although those plants left in their original sites will seldom be as good as those which were transplanted, as transplanting benefits Brussels sprouts; the plants grow stronger and produce earlier and better crops.
The time to transplant is when all danger of frost is past, either in late spring or early summer. The plants should be between 10-15 cm (4-6”) high, but not drawn and leggy, with four or five true leaves present. It is essential to allow plenty of space between Brussels sprout plants: allow 75-90 cm (2-½ – 3’) between rows with the greater spacing for the larger varieties, and 45 cm (l-1/2’) between each plant in the row. It is important to plant deeply because the plants are mainly shallow-rooting, and the roots have to support a tall, heavy-headed superstructure. A good rule to follow is to plant with the lower leaves just resting on the soil.
A day just after a heavy rain is the best time to transplant. If this is not possible, or in a particularly dry season, water the site thoroughly first. If you can water the seed-bed the night before, so much the better, as the plants will then be well watered. Prepare planting holes with a djbber and fill these with water as well. Put the plants in carefully, to the correct depth, and firm the ground well around them to anchor the roots and encourage the development of tight button sprouts. Do not forget to protect the plants from bird attacks; indeed, it is a good idea to have them netted or in a permanent cage.
Early sprouts, ready from late summer onwards, are considered desirable by many gardeners, although this is the time of year when summer vegetables such as runner beans andare both plentiful and cheap.
If you are determined to have early sprouts, then sow in mid- to late winter.
Because sprouts require a long period of growth, and the last frosts sometimes occur in late spring, you will have to sow the seeds under glass. For germination to take place, the temperature of the soil must be 10-13°C (50-55°F); if the winter is mild you can use an unhealed greenhouse or conservatory indoors, or sow them outdoors under cloches or frames. If the winter is particularly cold, either delay sowing until the weather warms up and accept that early crops will not be possible, or use a slightly heated greenhouse.
Sow the seed in boxes filled with a good quality seed compost. As soon as the seedlings show the first pair of leaves, they are pricked out, or transferred from seed boxes to pots or trays which, like the seed boxes, also need the protection of glass or plastic. The seed boxes, pots or trays should contain a fine soil or potting compost. Transplant the seedlings 5 cm (2”) apart in all directions.
If you use trays or pots, you can place them outside the greenhouse, and take the cloches off, or open the frame light, on mild days, to allow the plants to harden off. Plant them into their final positions in early to mid-spring, depending on their degree of maturity. They may continue to need protection at night if the weather is very cold.
To sow the seed directly in a cold frame, prepare the soil by watering it thoroughly so that further watering will not be necessary for some time. Sow the seed thinly in mid- to late winter and cover with 0.3 cm (1/8”) of fine soil. Close the light and cover it with a mat until germination has taken place; on warm sunny days, open the frame so that air can circulate around the plants. They will still need protection with the light in periods of heavy rain or extreme cold, particularly if frost threatens at night, when the mat should be replaced also. Thin them to about 10 cm (4”) apart in all directions, and plant them out in mid-spring. Remember your bird protection.
In districts which have a mild winter, the seed is sometimes sown in sheltered borders in autumn and protected by temporary arrangements of glass or plastic against any winter frosts, ready for transplanting in early spring. The main drawback with autumn planting is that autumn-sown plants are much more likely to bolt, or run to seed, without producing sprouts. Also, an unexpectedly cold winter can bring disaster to the whole crop.
Care and development of Brussels Sprouts
Remember that sprouts need plenty of water when young, and blowsy, loose buttons often result due to insufficient water at this stage. In hot, dry weather this is particularly important.
A mulch of rotted garden compost or farmyard manure put round the plants about a month after planting will help to keep the soil moist and supply a little more plant food. If you give too much nitrogen while the plants are growing, it will result in blown sprouts later, so any addition of compound fertilizers should be done with caution, and in general only if the soil is very light and quick draining. Avoid sulphate of ammonia and nitrate of soda completely, as they are very rich in nitrates—excessive applications could quickly ruin both taste and quality of your sprouts.
Summer care consists mainly of keeping the surrounding soil free from. Remember, though, that the roots of Brussels sprouts are very shallow and also widespread, so hand is best. If you do hoe, hoe lightly and shallowly across the surface to avoid damage. If any leaves at the bottom of the plant become yellowed or decayed, remove them immediately, or infection may spread to the sprouts and damage the crops.
If the sprouts are a tall-growing variety, or if they are on a windy site, stake the plants in early autumn, placing the stake on the windward side. Two ties are usually necessary. It also helps if you earth-up round the plants to the level of the lowest leaves at this time. Earthing-up, besides protecting the plants from wind-rock, throws excess moisture away from the stems and gives some protection from frost.