Spinach is a cool-season plant that grows best at 16-18 Celsius degrees (61-64 F) but will also grow at lower temperatures. Small plants and seedlings may survive at as low temperatures as -9 Celsius degrees (16 F). For best crops you should grow cultivars that are recommended for your area.
Spinach will tolerate light shade during summer and will need a soil with medium nitrogen levels for an optimal growth. Spinach must be sow in cool seasons as it will not germinate at temperatures above 30 Celsius degrees (86 F). Sow in situ, placing individual seeds about 2.5 cm apart in rows spaced about 30 cm apart.
For a continuous crop of spinach you should sow it in succession, after seedlings of the previous sowings have appeared. Thin early to about 7 cm for young plants or to 15 cm apart for large plants. Spinach may also be grown as a cut-and-come-again seedling crop for use in salads. For this you should sow it in early spring and early autumn under cover and in late summer for an over-wintering crop in the open.
Harvest your spinach by cutting leaves between five and ten weeks after sowing at any stage once the plants are about 5 cm tall. You can either cut individual leaves or cut the heads about 2.5 cm above the ground and leave them to re-sprout. Also you can pull up whole plants if you do not want to keep them for a next crop.
In warm areas you must harvest the plants while young, before they start to run to seed. Use the leaves fresh soon after picking or store them by freezing for later use.