Gadenin日本語Get the appLime the bed two to three weeks ahead
Cabbage wants a soil pH between 6.5 and 7.0, which is higher than most vegetables and considerably higher than the acid soil many gardens drift towards. The reason is not just nutrition: clubroot, the one disease that can end cabbage growing in a bed for years, is far less active in soil near neutral. Getting the pH right is the single most useful thing you do before planting.
Work garden lime into the top six inches (15 cm) of the bed two to three weeks before you plant, and put the compost and fertilizer in afterwards rather than at the same time. Lime and nitrogen fertilizer applied together react and you lose nitrogen to the air. If you have never tested your soil, a cheap pH kit is worth more here than on any other crop.
| Soil pH | What it means for cabbage | Action |
|---|---|---|
| Below 5.5 | Growth checked, clubroot thrives | Lime well and wait three weeks before planting |
| 5.5 to 6.4 | Workable but not ideal | A moderate dose of lime lifts it |
| 6.5 to 7.0 | The target range | No lime needed this season |
| Above 7.5 | Boron and manganese become hard to take up | Do not lime. Add compost instead |
Spacing decides head size
Cabbage spacing is a direct trade between the size of each head and the weight you get off the bed. At 14 inches (35 cm) apart you get compact heads that mature slightly earlier and store well. At 18 inches (45 cm) you get noticeably larger heads but fewer of them. Crowding below about 12 inches (30 cm) does not give you small heads so much as no heads at all, because the plants shade each other and never build the leaf area heading requires.
Leave 18 to 24 inches (45 to 60 cm) between rows whatever spacing you choose within the row. You need to be able to walk between them without brushing the outer leaves, because those big outer leaves are the engine that fills the head and every one you snap off costs you head weight.
| Spacing in the row | Head you can expect | Best for |
|---|---|---|
| 12 in (30 cm) | Small, and some plants may not head | Only for early types cut young |
| 14 in (35 cm) | Compact heads, about 2 lb (1 kg) | Small beds, storage cabbage |
| 16 in (40 cm) | The general purpose spacing | Most gardens |
| 18 in (45 cm) | Large heads, 4 lb (2 kg) and up | Late types and rich soil |
Plant at the same depth and firm it in hard
Set the plant so the top of the rootball sits level with the surrounding soil and the lowest true leaves clear the ground. Burying the growing point stops the plant dead, and planting proud of the surface leaves the rootball to dry out. The one exception is a stretched seedling with a long bare stem, which you can sink up to its seed leaves.
Then firm it, and firm it more than feels comfortable. Press the soil down around the rootball with your knuckles until the plant resists a gentle tug on a leaf. Cabbage builds a heavy top on a shallow root plate, and a plant that rocks in the wind tears its own fine roots, which is a common reason a plant sits there for weeks doing nothing after planting.
- Water the tray an hour before A moist rootball slides out intact and does not shed compost. A dry one crumbles and half the roots break off as you handle it.
- Make the hole slightly larger than the rootball Set the plant in, backfill and level it off with the top of the rootball flush to the soil surface.
- Firm with your knuckles Press down all around the stem. Tug a leaf gently: the leaf should tear before the plant lifts. That is firm enough.
- Water into a shallow basin Leave a slight dish around the plant and fill it twice. This soaks the rootball itself rather than running off across the bed.
Plant late in the afternoon or on an overcast day. A cabbage planted at midday in full sun spends its first afternoon wilting instead of rooting, and the check is visible a fortnight later.
Cover the bed the same day you plant
Cabbage root fly lays its eggs at the base of the stem within days of planting, and the maggots eat the roots away before you see anything above ground. Cabbage moths and butterflies find the plants almost as fast. Fine insect mesh laid over hoops on the day you plant removes both problems for the whole season, and it is far more effective than anything you can spray afterwards.
Bury the edges of the mesh in the soil or weight them down all the way round. A gap of an inch is an open door. Keep the mesh high enough that the leaves are not pressed against it, because a caterpillar hatching on a leaf touching the mesh from outside makes the whole exercise pointless.
- Hoop the bed before you plant Put the hoops in first, while the bed is empty and easy to work. Allow enough height for a mature cabbage, about 18 inches (45 cm).
- Seal every edge Bury the mesh edges or hold them down with timber or bricks along the whole perimeter. Check them again after windy weather.
- Add a stem collar as a backup A disc of card or felt about five inches (13 cm) across, slit to the center and fitted around the stem, stops cabbage root fly laying at the base.
Rotation: not in the same bed for three years
Clubroot and cabbage root fly both build up in soil where brassicas are grown repeatedly. Leave at least three years, ideally four, before cabbage returns to the same ground, and count every brassica against that rota, including kale, broccoli, radish, turnip and mustard greens. Gardeners frequently break the rotation without realizing, because radish and turnip do not feel like cabbage.
Draw the bed layout each year and keep it. A simple sketch of what went where takes a minute and it is the only way to be sure four seasons later. If clubroot ever appears, mark the exact spot: those plants have to be lifted whole and taken off the plot, and you will want that bed limed hard and kept clear of brassicas for far longer than three years.