Gadenin日本語Get the appThe shape of the season
This crop runs backwards compared with most vegetables. You sow it as the summer heat breaks, grow it hard through the mild weeks of early autumn, and harvest through the cold end of the year, when the plants have stopped growing leaves and are pushing flowering stems instead. The whole plan hangs on getting a large plant built before the cold arrives, because the size of that plant is the size of your harvest.
From sowing to the first cut is roughly seven to ten weeks depending on how warm the establishment period was. From the first cut to the last usable shoot is another five to eight weeks in the open, or longer under a low tunnel. That puts a single sowing in production for a substantial part of the cold season, which is why one sowing is usually enough in a home garden.
If you want continuity rather than a peak, make two sowings about three weeks apart. The second one gives smaller plants that come into production as the first is tailing off, and it also insures you against losing the first sowing to heat or flea beetle.
| Stage | Timing | Main jobs | Decision point |
|---|---|---|---|
| Ground preparation | Before the heat breaks | Compost dug in, bed raked, mesh hoops ready | Has this ground carried a brassica in the last three years? |
| Sowing | As summer heat breaks, 8 to 10 weeks before first hard frost | Sow shallow, firm, shade, water twice daily | One sowing or two three weeks apart? |
| Establishment | Weeks 1 to 3 | Thin at first true leaf, mesh stays on, keep surface damp | Is the stand thin enough to be worth resowing? |
| Bulking up | Weeks 3 to 7 | Nitrogen feed every two weeks, earth up, mulch, remove mesh | Are the plants going to reach full size before the cold? |
| First cut | Weeks 7 to 10 | Cut the main stem low, at the fourth or fifth leaf | Cut low for volume, or high for length and then clear? |
| Side shoot run | Five to eight weeks after the first cut | Cut every two to three days, feed every second or third cut | Is it time to put row cover or a low tunnel on? |
| Winding down | Deep cold | Take the last usable shoots, stop feeding | Clear the bed or leave a few plants to flower? |
The three decisions that actually matter
The first is the sowing date. Too early and the plants meet heat and flea beetle at their most vulnerable and may bolt short in warm weather; too late and they go into winter as seedlings and give you almost nothing. The safest reading is to count back eight to ten weeks from your first expected hard frost and sow at that point or a little before.
The second is where to make the first cut. Low, at the fourth or fifth leaf, for a long run of side shoots; high, just under the buds, if you want one long stem and are clearing the bed for something else. There is no way to change your mind afterwards, so decide before the knife goes in.
The third is whether to cover. Row cover or a low tunnel goes on before the hard weather rather than during it, and it typically adds three to five weeks to the cutting season. The cost is worse aphids and worse mildew under the cover, both of which you manage by opening it on mild days and looking inside.
Ending the season
The crop tells you when it is done: shoots start budding at three or four inches (8 to 10 cm) instead of eight, and they are the thickness of a straw. At that point the plant is out of stored reserves and there is nothing to be gained by keeping the bed occupied. Pull the plants, take the roots out of the ground rather than leaving stumps, and do not plant another brassica in that ground for at least three years.
Two things are worth doing before you clear it. Leave two or three plants to flower properly if there is anything flying that early in the season, because a mass of yellow brassica flowers in late winter is one of the earliest nectar sources available. And if the bed is coming out early, sow a quick cover crop or spread compost over the bare soil rather than leaving it open through the wet.
Do not save seed from these plants unless you are keeping them well isolated. Brassicas cross freely with anything else in the family flowering nearby, and seed saved from a mixed garden gives you an unpredictable plant that may not be worth the bed space it takes.
- Judge the end by shoot size, not by date When shoots bud at under four inches (10 cm) and are pencil-thin or less, the plant has finished. Pull it rather than waiting for a hard frost to make the decision.
- Take roots out of the ground Brassica stumps left in place harbor root fly and rots into the following season. Lift the whole root and remove it from the bed.
- Rest the ground Follow with a non-brassica crop and keep at least a three year gap before brassicas return to this bed. This is the cheapest disease control available.
The records that make next year easier
Four dates carry almost all the value: the sowing date, the date the first bud cluster became visible, the date of the first cut, and the date of the last usable shoot. Together they tell you the length of your establishment period and the length of your harvest, and they let you move the sowing date deliberately next year instead of guessing.
Add a note of where each row sat in the bed and how sheltered it was. Differences across a single bed are often larger than differences between sowing dates, and once you know which corner produces first you can put your earliest sowing there on purpose.
Finally, note the first frost date and how the plants looked a week after it. That is the observation that tells you whether you need to cover next season, and it is the one people never remember accurately without writing it down.