Harvesting New Zealand Spinach: Picking Tips, Oxalates and Why You Cook It

Pick tips, not leaves

First harvest comes about six to eight weeks from sowing, once the plant is branched and has plenty of growth to spare. Take the top three to four inches (8 to 10 cm) of a shoot, cutting or snapping just above a pair of leaves. That gives you a handful of young leaves plus the soft succulent stem, which is good eating in its own right, and it leaves a joint that will push out two replacement shoots.

Do not strip individual leaves off the length of a stem. It is the natural instinct if you are used to picking chard or true spinach, but here it gives you a bare stem with no growing point removed, so the plant carries on extending instead of branching, and you get one harvest from that stem rather than a season of them.

The right rhythm is twice a week in warm weather, weekly at minimum. That frequency is what keeps the whole plant in soft young growth. Leave it a fortnight and the tips you eventually pick are thicker, coarser and stronger flavored, and the plant has spent the interval setting capsules instead.

Pick in the morning while the leaves are full of water. Tips cut in mid-afternoon heat go limp within an hour and never fully firm up again, however long you stand them in water.

Oxalates, and why it is cooked

The leaves contain oxalates, in the same way that true spinach, chard and sorrel do. In practical kitchen terms that is what gives raw leaves the faintly dry, chalky feeling on the teeth, and it is the reason this plant is treated as a cooked green rather than a salad green. A few young leaves raw in a mixed salad are fine. A bowl of it raw, several times a week, is not the way to eat this crop.

The fix is simple and it is what growers everywhere already do: blanch it. Drop the tips into plenty of boiling water for one to two minutes, then drain and discard that water. A good share of the oxalate is soluble and leaves with the cooking water, and the leaves come out softer, milder and greener. Squeeze the drained greens gently before you use them in anything else.

That one step is worth building into your routine, because it changes what you can do with the crop. Blanched and squeezed, it goes into stir-fries, soups, gratins, egg dishes and pasta without the astringency, and it freezes well. Steaming or long simmering in a dish where you keep the liquid does not have the same effect, since the oxalate stays in the pot.

The stems are as good as the leaves once blanched, and hold their texture better. Do not strip and discard them out of habit carried over from true spinach.

Keeping the plant producing all summer

The limit on your harvest is not the plant's capacity but your discipline in picking it. Three or four established plants picked twice a week keep a household in cooked greens right through the months when nothing else leafy is worth growing, and they carry on until the first cold nights.

Take no more than about a third of the plant's foliage at a picking, and work around the whole mound rather than clearing one side. An evenly picked plant stays evenly leafy; a plant stripped on the sunny side gets scorched stems there and puts all its regrowth into the shaded half.

Keep an eye on the leaf joints while you pick. Any flowers or hardening capsules you find should come off with the shoot, because a plant carrying seed slows its leaf production noticeably. Picking and de-seeding are the same job here and it takes no extra time if you do it as you go.

1. Cut above a leaf joint Make the cut a quarter inch (5 mm) above a pair of leaves. New shoots come from those buds. A cut in the middle of a bare internode leaves a stub that dies back before anything regrows from it.
2. Snap by hand where you can Young tips break cleanly between finger and thumb, which is faster than reaching for tools and leaves a good wound. Use clean scissors on anything thicker than a pencil rather than tearing it.
3. Work all round the plant Pick a little from every side each time rather than clearing one section. It keeps the mound even, avoids sun-scorched bare stems, and keeps the whole plant in the same stage of growth.
4. Record your first and last picking dates Write down the date of your first real harvest and the date the plant stopped being worth picking. Those two dates define your productive window and tell you next year whether to sow earlier or grow one plant fewer.

After picking: handling and storage

The tips are succulent and they bruise. Handle them like a soft herb rather than like a bag of kale: keep them loose, do not press them down in a bucket, and get them out of the sun immediately. Crushed patches go dark and soft within a day, and the whole bag goes off from there.

Fresh tips keep three to five days in the fridge in a loosely closed bag with a sheet of kitchen paper to absorb condensation. That is the honest limit, and it is fine, because on a crop you can pick fresh twice a week for four months there is no reason to harvest a week ahead.

For a real surplus, blanch for one to two minutes, cool immediately in cold water, squeeze the water out firmly and freeze in portions the size of a meal. That is the same blanching step you would do anyway, so it costs nothing extra, and frozen portions go straight into soups, gratins and pasta over the winter. Drying is not worth the trouble; the leaves are too watery and lose both texture and flavor.