Spinach

Light and exposure

In spring and autumn, spinach takes the sun without a problem, it even needs it to grow fast. It is in summer that it must be protected: in partial shade, at the foot of a row of beans or behind a taller plant, it bolts to seed distinctly later.

The trap here is not the lack of light but the excess of heat combined with long days. Spinach planted in full sun in June is doomed to flower. So save the open, sunny spots for the March and September sowings, and keep a cool corner to attempt a summer crop.

Watering

Spinach wants permanently cool soil. This is the point that decides everything: soil that dries out, and the plant takes the water stress as a signal of the end of life and bolts to seed at once. Water regularly, without jolts, especially in dry, windy spring weather.

A light mulch between the rows keeps the base cool and spaces out the watering. In autumn, the rain often does the job for you, but keep an eye on the young August sowings while it is still hot and dry: this is the moment when they are thirstiest.

Soil and repotting

A rich soil, cool and well supplied with nitrogen gives the best leaves. Spinach is greedy for nitrogen, that is what makes it green and fleshy. An addition of ripe compost before sowing, or a bed that received manure the previous season, suits it perfectly. It appreciates a soil that does not become too acidic.

Sow directly in place, spinach transplants poorly. Draw shallow furrows, one to two centimetres, spaced twenty-five to thirty centimetres apart. Sow thinly then thin out to ten centimetres along the row once the young plants have come up: crowded, they grow leggy and bolt faster.

Temperature and humidity

Spinach is a cool-season vegetable, and that is where all its Belgian character lies. It germinates and grows well between 10 and 20 degrees, resists frost and withstands sub-zero temperatures once established. Above 25 degrees and under the long days of June-July, it triggers its bolting and becomes unusable.

The critical point here is therefore not the cold, which it takes, but the heat and the length of the day. Avoid high summer. A hardy autumn sowing spends the winter outside under a cold frame or a simple winter fleece, gets through our zone 8a frosts and restarts as soon as February-March when the light returns.

Pruning and upkeep

There is no pruning as such, but a piece of care that counts: thinning. As soon as the seedlings have two or three true leaves, pull out the weakest to leave about ten centimetres to those that remain. The young ones pulled out are eaten in salad, nothing is wasted.

Hoe and weed regularly, spinach hates the competition of weeds. Watch for the appearance of a central stem that lengthens and leaves that become pointed: this is the start of bolting. At this signal, harvest everything that remains without waiting, the quality will only decline.

Pests and diseases

Spinach downy mildew, caused by Peronospora farinosa, is enemy number one in our humid climate. It shows as yellow spots on the top of the leaves and a greyish-purple felting on the underside, and progresses fast in mild, damp weather, exactly our autumns. Air the rows, water at the base in the morning, and choose so-called mildew-resistant varieties, common today, which settle a good part of the problem.

As for pests, slugs and snails devour the young seedlings, especially the August ones when the soil stays moist: this is the main risk at emergence. Collect them in the evening, set barriers, or sow a little thicker to compensate for losses. Aphids can also colonise the underside of the leaves in spring.

Propagation

Spinach is propagated only by sowing, directly in place because it copes poorly with transplanting. The seeds germinate in the cold, from 5 degrees, which allows very early sowings. Emergence takes one to two weeks depending on temperature, slower in the cold.

If you want to harvest your own seeds, let a few plants bolt at the end of the season. Spinach is dioecious, there are male plants and female plants: keep several to ensure pollination by the wind. The ripe seeds are harvested dried on the plant, at the end of summer, and keep for four to five years.

Month-by-month care calendar

Green Hub tips

• The August-September sowing is the real winner in Belgium: autumn harvest, overwintering under fleece, and a very early restart in February-March.
• Never let the soil dry out. Water stress is the first trigger of bolting, even before the heat.
• Choose mildew-resistant varieties: under our humid autumns, it is the disease that spoils the most harvests.
• Always sow in place and thin out to ten centimetres. Spinach transplants poorly and bolts faster when it is crowded.