When and How to Harvest Kale for a Long Picking Season

Pick outer leaves and never the crown

Kale is a cut-and-come-again crop, not a one-off harvest. New leaves emerge only from the single growing point at the top of the stem, so as long as that point is intact and there is enough leaf below it to feed the plant, it keeps producing. Cut the whole head off and you get nothing more.

The rule is to take the largest outer leaves and always leave at least eight healthy leaves in the central rosette. From a mature plant that means three to five leaves per picking, roughly twice a week in warm growing weather and once a fortnight in cold. Snap each leaf downwards and sideways at the base of its stalk, or cut with a knife close to the stem, leaving no stub to rot.

1. Start when the plant has ten true leaves That is usually 55 to 75 days from sowing. Picking earlier is possible but slows the plant down for the rest of the season.
2. Work from the bottom of the plant up The oldest leaves are lowest. Take those and leave everything in the upper rosette, which is where the plant's engine is.
3. Leave eight leaves in the crown Count what remains before you stop. Below eight, growth slows noticeably and the plant takes two or three weeks to catch up.
4. Take yellowed leaves off at the same time Anything yellow or holed comes off with the harvest, whether you eat it or not. It is not feeding the plant and it shelters pests.

A leaf about the size of your outstretched hand is at its best. Much bigger than that and the midrib is woody and the flavor turns sulfurous, though those leaves are still fine cooked long and slow.

Frost makes the leaves sweet

Kale genuinely does taste better after cold weather, and the mechanism is straightforward. As temperatures fall towards freezing the plant converts stored starch in its leaves into sugars, which lower the freezing point of the cell sap and protect it from damage. The result is measurably sweeter and less bitter leaves.

The effect needs a real frost, not merely a cool night. Two or three nights below 28F (minus 2C) make an obvious difference, and the leaves stay sweet as long as the cold holds. This is why an autumn-sown crop picked through winter is worth far more than a spring-sown one picked in summer heat, when the same plant tastes coarse and peppery.

Pick in the morning and cool the leaves fast

A kale leaf is more than eighty percent water and it starts losing that water the moment it leaves the plant. Leaves picked in the cool of the morning are fully turgid and keep about twice as long as the same leaves picked at midday in full sun. If you must pick in the afternoon, get them out of the sun immediately and into a bag.

Do not wash leaves you intend to store. Surface water on kale accelerates rot at the cut ends and along any bruised edge. Wash it when you are about to eat it. If the leaves have already gone limp, standing the cut stalks in cold water for an hour will bring most of the crispness back.

1. Pick early, before the sun is on the bed Leaves picked at dawn are full of water and firm. The same leaves at 2pm are already slightly wilted before they reach the kitchen.
2. Bag them straight away Take a bag or box to the bed and put leaves in as you cut. Ten minutes lying on a warm path costs you days of storage life.
3. Store dry, loosely bagged, in the fridge A loosely closed bag in the crisper drawer holds them about a week. A sealed airtight bag traps ethylene and moisture and they go slimy faster.
4. Revive limp leaves in cold water Stand the stalk ends in a jug of cold water for an hour in the fridge. Fully limp leaves that have not yellowed will firm up again.

Blanch and freeze the glut

A row of kale in full production makes far more than most households eat, and the surplus freezes well provided you blanch it first. Blanching deactivates the enzymes that would otherwise turn frozen kale bitter and gray over a couple of months. Skipping it is the single reason home-frozen kale disappoints.

Strip the leaves from the midribs, drop them into boiling water for two minutes, then straight into iced water to stop the cooking. Squeeze out as much water as you can, portion into bags and freeze flat. Frozen this way it keeps its color and flavor for eight to ten months and goes straight from the freezer into soups and stews.

The end of the plant, and the spring shoots

As days lengthen in spring an overwintered kale switches from making leaves to making a flower stem. The center of the rosette elongates, the leaves get smaller and narrower, and the flavor of the ordinary leaves turns bitter. Most people pull the plant at this point, which is a waste.

The flower shoots themselves, picked while the buds are still tight and yellow has barely shown, are one of the best things the plant produces. Snap off six inch (15 cm) lengths and cook them like sprouting broccoli. Picking the shoots encourages more side shoots for another three or four weeks. Once the flowers open properly the plant is finished, so pull it, and note the date it began to bolt: that date is what tells you whether next season's sowing was correctly timed.

1. Watch for the center elongating The first sign is the growing point rising and the newest leaves becoming narrow and pointed. Bitter ordinary leaves confirm it.
2. Pick the shoots while buds are tight Snap six inch (15 cm) shoots off while the buds are still green and closed. Once they show yellow petals the texture goes woody.
3. Keep picking to get more shoots Every shoot you take triggers side shoots below it. A well-picked plant gives three or four weeks of shoots before it exhausts itself.
4. Pull the plant and record the date When flowers open fully, pull it and get it out of the brassica bed. Note the bolting date alongside the sowing date to judge next year's timing.