A robust Brussels sprout variety, with small, compact sprouts that thrive in cold weather.
About the variety. Easy to grow, it produces round, firm-headed sprouts with an excellent, consistent flavour; it thrives in cold climates and even improves after light frosts.
Itinerário técnico
Como cultivar brussels sprout groninger?
Um guia de cultivo passo a passo, da sementeira à colheita.
pH ideal 6.5 to 7.5Temperatura ideal 15 to 20 °CCompasso 50 to 60 cm in the row, 65 cm between rows
Sementeira
Sow in trays one or two centimetres deep at 15 °C to 20 °C. Germination takes five to ten days. Transplant at four to six true leaves, about five weeks later, setting the stem in up to the first leaves and firming the soil very well: a loosely planted sprout plant rocks in the wind and gives loose sprouts. Water well on transplanting day and fit the cabbage root fly collar straight away. Sow from March to May: the cycle is long and the sprouts only come good with autumn and winter cold.
Solo
It wants firm, deep soil, rich in organic matter and never acid: the ideal pH is between 6.5 and 7.5, and acid soil invites clubroot. It likes settled rather than fluffy soil: firm the ground lightly around the plant after transplanting. Minimum four year rotation away from any other brassica, radish, turnip and rocket included.
Clima
It is a cool weather crop, at its best between 15 °C and 20 °C, and its flavour improves after a frost. Strong heat gives open, loose sprouts instead of firm closed buttons. On the Portuguese coast it grows through the whole winter without trouble. Inland in Portugal and Spain night frosts do it no harm, but the summer there is too hot and dry for it. In France and Germany it is a summer and autumn crop, and in a cold winter a fleece or a low tunnel keeps the leaves in good condition well into the cold season. In Italy it is an autumn and winter crop in the centre and south, as in Portugal, and a spring and autumn crop in the north, where the Po valley winter is too hard to leave it outside unprotected.
Fertilização
This is a hungry crop. Work two to three kilos of well rotted compost into each square metre before planting, with a handful of wood ash for potassium. Once growth is away, feed with a liquid organic fertiliser every two or three weeks, moving from a balanced formula to a higher potassium one as cropping begins. Avoid excess nitrogen, which gives lush leaves, a poor crop and a lot of aphids.
Rega
Water regularly and generously, because the leaves transpire heavily. Irregular watering gives loose sprouts that open up: water without gaps, above all from late summer onwards, when the buttons swell. Water at the base and mulch the soil with straw to smooth out the swings.
Controlo de Infestantes
Hand weed in the first weeks, while the plant is small and loses every contest for light and water. Once it is established, mulch with five to seven centimetres of straw, dried grass or leaves: it holds weeds back, keeps moisture in and stops rain splashing soil onto the lower leaves, which is how most diseases begin. Always hoe shallowly so you do not cut the roots running just under the surface.
Controlo de Pragas
Flea beetle, a small jumping beetle, riddles young leaves with round holes in hot dry weather: keep the soil moist and cover with fine mesh from sowing. Cabbage white caterpillars and diamondback moth eat the leaves from within: apply Bacillus thuringiensis while the caterpillars are small and check the underside of the leaves every week. Cabbage root fly lays at the collar and the larva destroys the root: a cardboard or felt collar around the stem stops the egg laying. Grey cabbage aphid forms waxy colonies on the shoots and is dealt with using potassium soap. A fine insect mesh put on at planting solves almost all of these problems at once.
Doenças
Clubroot is the most serious disease: it deforms the roots, the plant wilts, and the fungus persists in the soil for close to twenty years. Prevent it with a four to five year rotation, good drainage and a pH above 7.0, corrected with lime. Alternaria makes dark concentric spots and downy mildew a grey bloom on the underside of the leaf; both like humidity, so space well and water at the base. Black rot enters at the leaf margins as a yellow V and is carried by seed and irrigation water. Clear all crop debris at the end and keep it out of the compost heap.
Colheita
Pick the sprouts from the bottom upwards as they firm up to the size of a walnut, twisting them off or cutting close to the stem. Never take the whole plant at once: the upper sprouts go on forming for weeks. The flavour improves greatly after the first frosts, so it is worth waiting. Strip yellow leaves off along the stem so air can move, and pinch out the top of the plant in October if you want more even sprouts. Allow about 180 to 200 days from transplanting to the first harvest of this variety. The reference colour is green, and that is what tells you it is ready.
