New Zealand Spinach Care: Water, Feeding and Managing a Plant That Sprawls

The crop that fills the summer gap

The reason to grow this is straightforward. True spinach runs to seed the moment the days lengthen and the weather warms, and from early summer onward it is unusable. New Zealand spinach is not a spinach at all, it is unrelated botanically, and it has no bolting response to heat or daylength. It simply keeps making thick, triangular, slightly furry leaves through the hottest weeks of the year and stops only when the cold arrives.

That changes how you treat it. You are not racing a bolting clock, so there is no rush and no need for successional sowings. What you are managing instead is a long, slow, sprawling plant that needs to be kept in leaf and kept in bounds for three or four months.

It is also tougher than it looks. It tolerates poor soil, coastal wind, salt and drought better than almost any other leaf crop, which is why it survives on beaches. Tolerating drought and producing well under it are different things, though, and the difference is what most of this care comes down to.

Watering for tender leaves

This plant will not die of thirst in a dry summer, and that is exactly the trap. What happens instead is that the leaves shrink, thicken, toughen and take on a distinctly stronger, more astringent flavor, and the whole plant slows down. You still have a crop, but it is a worse one. Water is the single biggest lever on quality here.

In open ground, a deep soak of about an inch (2.5 cm) twice a week through hot weather keeps the leaves large and tender, adjusted by how quickly your soil dries. Water the ground rather than the foliage and do it in the morning. Because the plant lies flat across the soil, an evening sprinkling leaves the whole mat of stems and leaves wet all night, which is how rots start underneath it.

Mulch does more for this crop than for most. Two inches (5 cm) of straw or shredded leaves under and around the plant holds moisture in the top few inches where the roots are, keeps the sprawling stems off bare soil, and stops rain splashing grit up onto the leaves you are going to eat. Spread it before the stems have run, because doing it afterwards means lifting a heavy tangle.

1. Test at a finger's depth Push a finger two inches (5 cm) into the soil near the crown. Damp means wait. Dry at that depth in hot weather means water now, and water enough to wet down to six inches (15 cm) rather than dampening the surface.
2. Read the midday wilt correctly Slight drooping in full afternoon sun that recovers by evening is normal transpiration, not thirst. Leaves that are still limp the following morning mean the soil is genuinely dry. Only the second one calls for action.
3. Water in the morning at ground level Put water on the soil around the crown, not over the top of the plant. A sprawling mat that goes into the night wet develops soft brown patches where stems press against damp soil.
4. Water containers daily in heat A large plant in a five gallon (20 L) pot in hot weather will empty it in a day. Containers are where this crop most often turns bitter, because nobody expects a drought-tolerant plant to need daily water.

If the leaves have gone small and harsh-tasting after a dry spell, water deeply and feed, then pick and discard the tough growth. The plant comes back into good condition within two weeks.

Feeding a plant you keep cutting

You are removing shoot tips every few days for months on end, and every tip you take is nitrogen leaving the garden. A well-fed plant answers by pushing out more soft growth; an unfed one gradually makes smaller, paler, harder leaves and puts its energy into flowering and setting those corky capsules instead. Since there is no fruit you are trying to ripen, you can be generous with nitrogen without any downside.

Dig two to three inches (5 to 8 cm) of well-rotted compost into the bed before you sow or plant. Once the plant is running and you have started picking, give a balanced liquid feed every two to three weeks through the main season. If the newest growth at the tips comes pale while the older leaves stay dark, that is nitrogen running short and it responds visibly within a week.

One caution worth knowing: this plant takes up nitrate readily, and heavy nitrogen feeding on a plant under drought stress concentrates it in the leaves. Feed steadily and moderately alongside good watering rather than throwing a large dose at a struggling dry plant.

Living with a plant that sprawls

Nothing about this plant is upright. It grows as a low mound that sends thick, brittle, succulent stems outward across the ground, and by late summer a single plant occupies a circle two to three feet (60 to 90 cm) wide and can smother a neighbor that was never meant to be shaded. Decide at planting time where you are willing to let it go.

There are three sensible approaches. Let it run along the ground where you have room, which is the least work and gives the heaviest crop. Grow it at the edge of a bed and let it spill over the side onto a path, which keeps the bed itself free. Or lift it onto a low frame or a few strung wires, which is not climbing exactly, because it has no tendrils and will not attach itself, but a mound supported eighteen inches (45 cm) off the ground stays much cleaner and is far easier to pick.

Whatever you choose, keep the stems off wet bare soil. Where a heavy stem lies on damp ground under mulch it will root at the joint, which sounds convenient but in practice gives you a spreading mat that is hard to pick and hard to remove at the end of the season. It is also where slugs live.

Note in your records how wide each plant finished the season, and how far it overran what you allowed for. That one measurement is what stops you planting it too close to something else next year.