Pickling Greens Growing Calendar: From Late Summer Sowing to Winter Harvest

The shape of the season

Unlike most leaf crops, this one has a single window rather than two. It is sown as summer heat breaks, grows through autumn into shortening days, and is cut through late autumn and winter after frost has improved it. A spring sowing is possible but rarely worth it: lengthening days push the plant into flower long before it reaches the size that makes it worth growing, and you end up with a small sharp plant and a flower stem.

So the year has a clear rhythm. Summer is preparation. Late summer is the sowing, the thinning and the pest battle, all compressed into about six weeks. Autumn is the long growing stretch when the plants build size and need almost nothing from you. Winter is harvest, and the bed is the storage.

Read the table by season rather than by month so it works wherever you garden. The two dates you need for your own site are when your summer heat reliably breaks and when your first hard frost usually arrives.

Late summer: six weeks that decide the crop

Everything that can go wrong with this crop goes wrong in the first six weeks. Sow as soon as daytime temperatures settle below about 80F (27C), watering the drill before the seed goes in, and cover the row with fine mesh the same day. Flea beetles are at their peak in exactly this weather, and an uncovered row of seedlings can be destroyed in a week.

Thin in three stages rather than one, taking each station from five seedlings to three at the first true leaf, to two at three inches (8 cm) tall, and to one when neighboring leaves begin to touch. Keeping spares until the danger has passed is free insurance, and everything you remove after the first round can be eaten.

Feed once with a nitrogen-rich liquid when the plants have five or six true leaves, and mulch as soon as the final thinning is done. From that point the plants take over. If they have reached ten inches (25 cm) across before day length drops below about ten hours, the crop is made, and nothing else is required of you.

1. Prepare the ground a week before you sow Fork in three inches (8 cm) of well-rotted compost and rake level while you are waiting for the heat to break. The window is short and you want to sow the day the weather turns, not start bed work then.
2. Sow in stations twelve inches apart Four or five seeds per station, half an inch (12 mm) deep, rows eighteen to twenty-four inches (45 to 60 cm) apart. Station sowing guarantees a plant at each spot and makes staged thinning simple.
3. Get the mesh sealed on day one Hoops, fine insect mesh, edges buried the whole way round. This single job prevents both of the crop's main pests, and it is worth more than everything else you will do this season.

Autumn and winter: growth, then holding

Through autumn the plants put on most of their size, and your job shrinks to keeping the water even and the base of the plants clear. Once every fortnight, lift the outer leaves, snap off anything yellowed or slimy, and take it out of the bed. Stop feeding a full month before your first hard frost so the plants harden rather than going into the cold soft and sappy.

Growth effectively halts once day length falls below about ten hours, whatever the temperature does. From that point the crop is holding rather than growing, and a plant that was half-grown when the light went will stay half-grown. This is why the sowing date matters so much and why sowing late cannot be corrected afterwards.

Frost is a benefit, not a threat. After two or three hard frosts the plant converts starch to sugar, the raw mustard edge softens, and the thick stalks become sweeter and cleaner tasting. Plants take repeated frost to around 20F (minus 7C) unprotected. A low tunnel or double row cover on hoops does not so much protect them as keep the leaves clean and undamaged, which makes the harvest more pleasant.

Cut the largest plants first and leave the rest standing, because in cold weather the bed is better storage than anything indoors. Harvest at midday once frozen leaves have thawed, since frozen leaves bruise into brown mush wherever you handle them.

1. Stop feeding a month before hard frost Late nitrogen produces soft growth that collapses and rots at the crown in the first freeze. A plant that hardened off a month earlier takes far more cold without visible damage.
2. Clear lower leaves every fortnight Yellowing leaves lying on damp soil are where slugs shelter and crown rot begins. Snap them off at the base and remove them from the bed rather than leaving them between the rows.
3. Cut everything before the plants bolt As light returns in late winter the plants resume growth and switch to flowering. Once the crown lifts and the newest leaves come narrow and upright, the stalks toughen within days. Take the whole bed.

Keep four dates for this crop: the sowing date, the date the canopy closed, the date of your first cut, and the date the last plants bolted. Two seasons of those four numbers will tell you whether to sow earlier or later, and how many stations you actually need, better than any general advice can.

What to do with the bed afterwards

Lift the stumps and roots when you cut the plants rather than leaving them in over winter. Brassica stumps left in the ground keep flea beetles, aphids and disease going into the next season, and pulling them gives you a free look at the roots for the swellings that indicate clubroot.

Do not follow this crop with another brassica. Cabbage, radish, turnip, mustard and rocket all share its pests and diseases, and repeating the family in one bed is how a garden acquires a lasting clubroot problem. Give the ground three years off from the family, and follow with a legume or an overwintering green manure to rebuild what the crop took out.

If the bed is empty through late winter, sow a green manure or cover it. Bare soil through winter rain loses structure and nutrients, and this crop takes a lot of nitrogen out of the ground in a short time.