We can Grow broccoli plants twice a year; we do not repeat sowing in between. We start spring sowing of broccoli in the middle or end of February. Planting for autumn and winter crops is done in May or, at the latest, in early June. We also sow broccoli for the third time for growing in a greenhouse, into which we transplant the seedlings in August and have a harvest in November and December.
According to biodynamics, broccoli is considered a flower, as we eat undeveloped flowers together with the stem. Its leaves are also edible. It appears in the garden in all seasons; growing winter broccoli for harvest in March is possible. We get more from one plant because several smaller ones sprout from the stem after the first picking of the primary inflorescence. If we miss the optimal picking time, the green heads open into clusters of yellow flowers.
How to Grow Broccoli Plants – When and How to Sow
Growing Spring Broccoli
To have early broccoli seedlings ready at the beginning of April, sowing is done about 45 days earlier. In February and early March, the conditions outside are not yet suitable, so we grow seedlings indoors or in heated rooms with enough light.
First, several seeds are sown in a larger container, where the seeds germinate. Sow in a moist substrate, and sprinkle the seeds with a dry substrate 0.5 cm thick. We germinate at a temperature between 18 and 22 °C, which also suits other plants that are germinated simultaneously. Since they successfully germinate in the dark, the container is covered, which enables better germination due to constant humidity. We uncover as soon as we see the first sprout, which can be as early as two days, and we immediately move it to a bright place.
When the “heart-shaped” cotyledons are nicely developed (within 7 to 10 days after sowing), the plants are transplanted into individual medium planting units with a high-quality substrate mixture.
We don’t wait long for the real leaves to start developing because the roots we would damage during picking also develop simultaneously. We carry out natural selection by picking because we choose good plants. If the plants have “stretched” up to now, we can plant them deeper when picking, right up to the cotyledons. We do not touch the roots of the plants but help ourselves with a wooden or plastic stick.
The plants are then placed in a bright place with a temperature between 18 and 22 °C, which corresponds to most plants grown from seedlings. Night temperatures can be as low as 4 °C. If we have more plants left after picking, we eat them as microgreens since they are already edible at this growth stage.
We water the seedlings regularly every other day, just like all the other seedlings we grow simultaneously. Before the seedlings are transplanted to the bed at the end of March or the beginning of April, they are hardened for at least 4 days against a southern wall or in a greenhouse to adapt to the outside temperatures, especially the nighttime temperature fluctuations.
When to Transplant Seedlings of Broccoli Outdoors and the Planting Distance
The first seedlings are transplanted outdoors when they have formed 3 to 5 true leaves or about 45 days after sowing. For the first sowings, this means the end of March, the beginning or the middle of April. The seedlings are planted at a distance of 50 cm in a zigzag pattern. This is true for most broccoli varieties, as there isn’t that much variation in size between varieties. After transplanting, the bed looks almost empty, but they will soon start to grow rapidly and occupy the empty space. These very early sowings must be covered with a garden cover, preferably over arches, as the garden cover must not squeeze the seedling. Plant deep or in a pile up to the first true leaves. Only lightly water the planting hole, as the soil is usually moist enough in the spring. In case of dry weather, water the entire surface of the tree abundantly.
In May, we still protect the plants with garden cover, which perfectly protects the young plants from the cold wind, cold nights, and flying pests. Then we replace the garden cover with an insect net on the bed until the last spring crop is harvested.
Growing Autumn Broccoli
For the autumn crop, we sow seeds for raising seedlings in May. These are varieties with a longer growing season, larger yields, and also better withstand hot summer days.
Growing seedlings in May is much easier because everything can be done outside next to the garden shed or greenhouse due to the higher temperatures. Just like in February, the seeds are first sown in a larger container and later planted in a medium planting unit. Since the plant is always outside, hardening, as with early seedlings, is unnecessary. We water every other day in May and June as the sun dries the substrate. At that time, the cabbage white butterfly (Pieris brassicae) is already active and can lay yellowish eggs on the underside of the seedling leaves, from which caterpillars develop, which eat most of the leaves in one day. Therefore, it is recommended to cover the seedlings with an insect net or a net with such holes to prevent access to butterflies.
When to Transplant Seedlings of Broccoli Outdoors and the Planting Distance
The seedlings are transplanted to the bed in June or at the beginning of July when they have between 3 and 5 true leaves, or around 30 days after sowing. Seedlings grow faster at this time than in spring. We plant them at a distance of 50 cm. We plant deep, up to the first leaves, so that the plant does not fall over under the weight of the heads. We can also plant in a heap. Water the planting hole and even the bed heavily, as it must also be soaked to the depth. We always behave according to the weather. If we transplant just before the rains, the seedlings will take root ideally. Cover immediately with any summer mulch. Like other brassicas, it is best to protect them from flying pests during the summer, preferably immediately after transplanting, with an insect net.
Early broccoli on the bed is replaced by winter leeks (seedlings) and carrots (sowing) at the end of June. After we harvest new potatoes, we use the bed for the autumn broccoli crop. Due to the larger adult plant, there is less possibility of combinations with several types of vegetables simultaneously on one bed.
Care for Broccoli
The transplanted seedlings are watered daily for the first week, especially in dry and sunny weather, then gradually as little as possible to allow the plant to take deep roots. We water at most once a week. Summer mulch (grass clippings and straw) suits broccoli from mid-May onwards. If the seedlings were not planted deep enough and they later start to droop, cover the stems with soil or mulch to make them more stable.
We purposely want the broccoli to form inflorescences in spring or autumn, as summer temperatures above 30 °C provoke too rapid development and opening of flowers and incomplete inflorescences.
All types of broccoli are protected with an insect net from mid-May to the end of October. If it is grown in a greenhouse, the side ventilation openings are also covered with an insect net to prevent the entry of any flying pests.
In a way, the nets still spoil the image of our garden. If we don’t have or don’t want an insect net, prepare a piece of cardboard (cabbage fly) for each seedling and stick some colorful butterflies (cabbage white) next to it.
Challenges and Pitfalls of Growing Broccoli
Young seedlings (stalks) like to be gnawed by weevils or attacked by ants that feed on the sweet plant sap that flows over the plant. Flea beetles can attack the leaves of young plants. This attack can be recognized according to the small holes in the leaves. These appear mainly after transplanting when they are still under “stress.” Later, the most damage to broccoli is caused by cabbage white, which feeds on the leaves. The best prevention in the spring is to cover the entire bed with a garden cover and, on hot days, with an insect net. An attractive protection against cabbage whiteflies is also artificial colored butterflies stuck on a shaft, which repel cabbage whiteflies. It is very timid and does not enter the territory of other butterflies. One artificial butterfly per three seedlings should be sufficient.
The biggest challenge is the cabbage fly (Delia radicum brassicae), whose female lays her eggs on the ground near cabbage plants.
Larvae hatch from the eggs and get their food from the underground part of the cabbage plants – they eat the roots. The cabbage fly has as many as three generations a year (in April, late June, and August). Depending on how she lays her eggs and where the larvae cause damage, the best protection is to prevent females from laying eggs against the stem. Use cardboard with a hole in the middle for a small number of broccoli seedlings. These act as a sort of soil “collar” around each plant. For this purpose, growers in large areas use agricultural foil with a small hole through which the plant grows.
If we have an attack of the cabbage fly one year and then grow cabbage in the same bed the following year, we can expect that the same bed has overwintered bugs, but they are not harmful. However, in the spring, the pupae will develop into adult flies, finding the plants faster and laying their eggs next to the new plants.
Broccoli florets are harvested when they are well formed but not yet blooming. Ripe inflorescences turn from dark green to yellowish as they enter the flowering stage. Broccoli heads are cut off along with the soft stem, which is also edible. Broccoli leaves are also edible and are used like spinach. The spring crop is harvested at the end of May, June, and July. The autumn ones are harvested before the autumn frost, in September, October, and the beginning of November. Winter broccoli gives us crops in the next calendar year, namely in March.
Both spring and autumn broccoli can be left on the bed after the main inflorescence has been collected, as the plant will sprout several smaller heads from the side shoots above the leaf stem. In 7 to 14 days, several smaller heads of broccoli can be harvested from the same plant. The stems and older leaves that remain after the harvested crops are composted. The stem is best crushed in an electric branch chipper or lawnmower.
THE TRICK FOR AN ABUNDANT HARVEST
When picking broccoli, always cut off the central inflorescence first and leave the plant. This encourages the development of many side inflorescences and increases the yield.
Broccoli tastes best straight from the garden. Freezing works best for more extended storage. In this case, just cut the raw buds into smaller pieces and freeze them.