Kale Growing Calendar: What to Do Through the Season

Four turning points define the year

Kale is one of the longest-standing crops in a home garden: a single autumn sowing can crop from late autumn right through to the following spring. Because of that length, the useful way to think about it is not in months but in four turning points, each of which decides something about the rest of the season.

The one that people get wrong is the first: sowing date. Everything else can be corrected as you go, but a kale sown four weeks late meets the cold as a small plant and never catches up, because growth stops below 40F (4C) and it simply waits, undersized, until spring.

The stage by stage list

The list below is written relative to your first autumn frost, because that is the date that genuinely differs between gardens and the date kale timing hangs on. It assumes a main sowing for autumn and winter picking, which is what most gardeners want from kale.

A spring sowing for summer leaves runs on the same sequence but compressed, and the summer crop is always coarser in flavor and under more pest pressure. If you only sow once a year, sow in late summer.

Late summer: get the bed and the sowing right

Preparation matters more for kale than for most crops because the plant will stand in the same spot for six months or more. Dig in two to three inches (5 to 8 cm) of well rotted compost, check the pH and lime up towards 6.5 to 7.0 if it is acid, and firm the bed by treading it. Brassicas root badly in loose, fluffy soil and a firm bed also holds a tall winter plant upright.

Sow into modules if the weather is still hot, keep them in light shade, and plant out at four to five true leaves. Water the transplants in generously and keep them damp for the first ten days; after that, a plant with roots down will look after itself in all but a drought.

1. Test and adjust the pH Aim for 6.5 to 7.0. Liming an acid bed several weeks before planting is also the single most useful thing you can do against clubroot.
2. Firm the bed by treading Walk the bed heel to toe after digging, then rake it level. A firm bed anchors a tall winter plant far better than a fluffy one.
3. Plant at four to five true leaves Set plants at final spacing, deep enough that the lowest leaves sit just above the soil. Water in and keep damp for ten days.
4. Net the row on the day you plant Do not wait for the first hole in a leaf. Cabbage whites find a new brassica bed within days.

Autumn: bulk it up before growth stops

This is the only window in which the plant can put on real size, so it is the one time feeding really pays. Side dress with a nitrogen-leaning feed every three weeks while temperatures stay above 60F (16C), keep the soil evenly moist, and mulch two inches (5 cm) deep once the plants are established.

It is also peak pest season. Do the pest check, the picking and the stripping of yellowed lower leaves as one job on the same day each week. Caterpillar eggs wiped off in ten seconds in autumn are the reason you have intact leaves in winter.

1. Feed every three weeks while it is warm A handful of granular feed scattered in a ring six inches (15 cm) from the stem and scratched in. Stop once nights are consistently cold.
2. Do everything on one fixed day Pick, check leaf undersides for eggs and aphids, and strip yellowed lower leaves together. A fixed weekly day is what keeps a long crop tidy.
3. Stake or earth up tall plants Once the bare stem passes a foot (30 cm), push in a cane and tie loosely, or draw soil up around the base against autumn wind.

Winter and spring: less work, better flavor

Once temperatures sit below 50F (10C) the plant slows right down and your job shrinks to picking. Stop feeding entirely, water only when the soil is dry an inch (2.5 cm) down, and expect to take three to five leaves per plant every week or two rather than twice a week. Kale is hardy to around 10F (minus 12C) unprotected, and a layer of row cover over hoops will carry it lower than that.

In spring the center of the plant elongates and leaf flavor turns bitter. Switch to picking flower shoots while the buds are still tight, keep picking to encourage more, and pull the plant once flowers open properly. Then move the brassica bed: the next kale should not go in the same ground for at least three years, and four is better.

Record the sowing date, the first picking date, the date frost first sweetened the leaves and the date it bolted. Those four dates turn every general rule above into a calendar that fits your own garden.