The trick to growing spinach is to grow it fast and harvest it fast, and use the right varieties in the right season. Spinach bolts as the days get long and when the soil gets hot. That’s why spinach is usually grown in early spring and fall, in low temperatures and short days. Some varieties do a little better in long day, hot conditions. Pick them promptly in hot weather. For summer harvests, try New Zealand Spinach. Continue reading below for tips on how to grow spinach from seed.
Latin
Spinacia oleracea
Family: Amaranthaceae
Difficulty
Easy
We Recommend: Monstrueux de Viroflay (SP713). Most of the spinach varieties we offer are hybrids that mature early and resist bolting. For growers, these may make the better choice. But we also love the open pollinated heirloom Viroflay, which stands apart from the rest for its sheer size. And the leaves stay tender and delicious even when the plant is fully mature. This is a very nice spinach for the home garden.
For Urban Gardeners: Try Space (SP704) in containers or even window boxes. Space is very compact and upright, holding its leaves skyward for easy harvesting. Plus it’s super fast growing and very tasty.
Season & Zone
Season: Cool season
Exposure: Full sun to partial shade
Timing
Spinach does best in cool weather. Direct sow in the period four weeks before, and three weeks after the last frost date. Spinach will bolt once days get long and hot. Some varieties grow enough to harvest before they bolt. For continuous supply, plant every 3 weeks.
Sow again in the middle two weeks of August for a fall crop that, if cut at the soil level, will come back early the following spring where winters are mild. Shade summer-sown seed beds, keep very well watered, and sow more seeds than you need, as warm soil will reduce germination rates marginally. Thin seedlings, and use cloche protection as cold weather approaches. Late sowings like this can be harvested into December – in mild winters if cloche protection is provided.
Optimal soil temperature: 5-20°C (45-70°F). Seeds should sprout in 7-14 days.
Starting
Sow seeds 1cm (1/2″) deep, 10 seeds per 30cm (12″), in rows 30-45cm (12-18″) apart. Thin to at least 5-8cm (2-3″) between plants, or further if you want larger leaves.
Days to Maturity: From direct sowing.
Growing
Ideal pH: 6.0-6.5. This heavy feeder requires rich soil. Dig in ¼-½ cup balanced organic fertilizer beneath every 1m (3′) of row. Overwintering spinach requires well drained soil.
Harvest
For baby greens, pick when the leaves are 7-10cm (3-4″) long. Individual leaves can be picked at anytime, until the plant has started to bolt. Cut the whole spinach plant just above soil level.
Seed Info
In optimal conditions at least 65% of seeds will germinate. Usual seed life: 3 years. Per 100′ row: 400 seeds, per acre: 174M seeds.
Diseases & Pests
Pale, soft tunnels on leaves are probably leaf miner damage. Prevent by covering with floating row cover. You can kill the little insect causing the damage by pinching it inside the leaf. Destroy any affected leaves. Downy mildew is a fungal disease that causes greyish mould on the leaves. To avoid it, provide ample ventilation and avoid overhead watering.