Gadenin日本語Get the appPrepare the bed two to three weeks ahead
Broccoli is a hungry, deep rooted plant that will be in the ground for three to four months. Work two to three inches (5 to 8 cm) of well rotted manure or garden compost into the top spit, and add a balanced granular fertilizer at planting. Ground prepared the same day you plant settles afterwards and leaves the plants standing proud, so give it a fortnight to sink.
Target a soil pH of 6.5 to 7.0. Brassicas grown below pH 6.0 are far more likely to pick up clubroot, and liming is the cheapest insurance you can buy on a plot with any history of it. Apply lime two to three weeks before the manure and fertilizer rather than at the same time.
| Job | When | Amount |
|---|---|---|
| Lime, if pH is below 6.5 | Three weeks before planting | Follow the label for your soil type |
| Manure or compost | Two weeks before planting | 2 to 3 inches (5 to 8 cm) dug in |
| Balanced granular fertilizer | A few days before planting | A handful per square yard (square meter) |
| Tread and rake | The day before planting | Firm enough to leave a shallow footprint |
Firm ground, not fluffy ground
This is the point most gardeners get wrong. Broccoli grows two to three feet (60 to 90 cm) tall and carries a heavy head on top, and in loose soil the wind rocks the stem, tears the fine roots and the plant simply stops. Firm brassica beds by treading them over with your weight on your heels, then rake the surface level.
The same logic applies to the planting hole. Set the plant, backfill, and then press hard with your knuckles either side of the stem. A properly firmed broccoli plant should resist if you tug a leaf: the leaf tears before the plant lifts. That is the test.
- Tread the bed before planting Walk the bed heel to toe across its width, then again along its length, and rake it level. You want the surface to take a shallow footprint, not to stay springy.
- Bury the stem to the lowest leaves Plant deeper than the plant sat in its cell, right up to the first pair of true leaves. The buried stem roots along its length and steadies the plant.
- Firm with your knuckles Press hard on both sides of the stem after backfilling. Then pull gently on a leaf: if the plant lifts out, it is not firm enough.
- Water into the hole, then again after Pour a pint (half a liter) into the hole before you set the plant, and water the base again once it is firmed. This settles soil against the roots with no air gaps.
Spacing sets head size, so choose deliberately
Broccoli spacing is a direct trade between the size of the main head and the total weight you pick. At 18 inches (45 cm) each way you get big central heads and plenty of side shoots afterwards. Squeeze the plants to 12 inches (30 cm) and the heads come smaller but they mature more evenly, which suits anyone who wants to cut a row over a fortnight rather than string it out.
Do not go below 12 inches (30 cm). Crowded broccoli produces small loose heads, holds moisture in the canopy, and gives you downy mildew and aphids sheltering where you cannot see them. If space is tight, grow fewer plants properly rather than more plants badly.
| Spacing | Main head | Best for |
|---|---|---|
| 12 in (30 cm) each way | 3 to 4 in (8 to 10 cm) across | An even cut over a short window |
| 15 in (38 cm) each way | 4 to 5 in (10 to 13 cm) across | A good general compromise |
| 18 in (45 cm) each way | 6 in (15 cm) and up | Big heads plus a long side shoot season |
| 24 in (60 cm) each way | Largest, but wasteful of ground | Sprouting types kept for months |
Protect the plant on the day it goes in
The first fortnight after planting is when the crop is most easily lost, and all three of the usual causes are preventable in the ten minutes it takes to plant. Cabbage root fly lays at the base of the stem within days of transplanting, pigeons strip a newly planted row overnight, and slugs take the growing point out of a plant that has not started growing yet.
Fit a collar around the stem, put mesh or netting over the row straight away, and check under the leaves on the second evening. Netting put up a week later is netting put up after the damage. If you are planting into a windy site, push a short cane in beside each plant and tie it loosely for the first month.
- Fit a root fly collar Slip a 5 inch (13 cm) disc of cardboard or felt around the stem, flat on the soil. It stops the fly laying at the base, which is where the maggots enter.
- Net the row the same day Use insect mesh on hoops with the edges buried. It keeps out pigeons, cabbage white butterflies and root fly in one go. Leave enough headroom for a three foot (90 cm) plant.
- Check the growing point on day two Look into the center of each plant in the evening. A slug that eats the growing point leaves a plant that will never form a head, and it is worth going out with a torch.
Do not plant broccoli where you grew any brassica in the last three years. Cabbage, kale, swede, turnip, radish and rocket all carry the same soil-borne diseases, and clubroot stays viable in the ground for many years.
The first ten days tell you if it took
A broccoli plant that has taken hold stands upright at dawn and puts out a new leaf from the center within ten days. Wilting at midday in the first week is normal and does not need action. What matters is what the plant looks like in the early morning.
If the plant is still flat at dawn, either the rootball never made contact with the soil or something is eating the roots. Lift one and look. A rootball that is dry inside while the soil around it is wet is a common failure: the compost in the cell repels water once it has dried out, and the only fix is to soak the plants thoroughly before they ever go in the ground.