Spinach is a cool-season annual. Plant spinach before the weather warms in spring and again as the weather cools in early autumn.
Spinach doesn’t grow well during long hot summer days or in wet weather.
Where to Grow Spinach
- Grow spinach in full sun. Grow spinach in partial shade in warm regions.
- Plant spinach in well-drained, loamy soil rich in organic matter. Add two inches of aged compost or a commercial organic planting mix to the planting beds before planting then turn the soil to 12 inches (30cm) deep.
- Spinach prefers a soil pH of 6.0 to 6.8.
- Spinach is hardy and thrives in cool weather; ideal spinach growing weather is 50°F to 70°F (10-21°C).
- Warm weather and long days will cause spinach to bolt—that is it will flower and go to seed.
Spinach Growing Time
- Spinach is a cool-season annual. It needs 6 weeks of cool weather from seed sowing to harvest.
- Spinach grows best when planted outdoors in early spring and then again in autumn. In mild-winter regions grow spinach outdoors in winter.
- Sow spinach indoors 6 to 8 weeks before the last average frost date in spring for transplanting out as early as 4 weeks before the last frost. However, seedlings may suffer transplant shock if the roots are disturbed at transplant time.
- Direct sow spinach outdoors or set out transplants 4 weeks before the last average frost date.
- In mild-winter regions, plant spinach in late summer or early autumn for harvest in autumn or winter; sow spinach for autumn harvest 6 to 8 weeks before the first fall frost.
- Spinach can be grown through the winter everywhere in a cold frame or plastic tunnel.
- Spinach started in autumn can survive the winter under thick mulch; plants will resume growing in the spring.
- Plant succession crops of spinach every 10 to 14 days.
- Don’t grow spinach through the summer in hot summer regions. Instead, grow New Zealand spinach or Malabar spinach which are heat tolerant.
Planting Spinach
- Plant spinach seed ½ inch (12mm)deep. Cover seed lightly with soil.
- Refrigerate seeds 1 week before sowing to help germination.
- Sow seed 2 to 4 inches (5-10cm) apart.
- Space rows 12 to 14 inches (30-35cm) apart.
- Spinach seed will germinate in 5 to 9 days at 70°F (21°C) Germination will take longer if the soil is cooler, about 21 days at 50°F (10°C).
- Thin spinach to 12 inches (30cm) apart when seedlings are 3 inches (7cm). Thin to the strongest seedlings. Remove weak seedlings by cutting them off at the soil level with scissors.
- Grow 15 plants per household member.
Container Growing Spinach
- Spinach will grow in a container. Allow one plant for each 8-inch (20cm)pot; in large containers plant spinach on 10-inch (25cm) centers.
- Spinach is heat-sensitive; move containers into the shade on warm and hot days.
- Containers will warm more quickly than garden soil in spring.
Companion Plants for Spinach
- Grow spinach with other greens and Plant spinach in the shadows of tall crops such as corn or pole beans.
Watering and Feeding Spinach
- Keep the soil evenly moist throughout the growing season to grow spinach quickly.
- Avoid splashing muddy water onto leaves; mulch around plants with straw or chopped leaves to avoid getting soil on leaves.
- Side dress plants with compost tea or a dilute solution of fish emulsion every two weeks during the growing season.
- Side dress spinach with aged compost at midseason.
Caring for Spinach
- Keep planting beds free of weeds to avoid competition for light, water, and nutrients.
- Cut weeds at soil level rather than digging them out; spinach has a deep taproot but shallow feeder roots that can be injured easily.
- Mature spinach plants can tolerate temperatures as cold as 20°F (-6.7°C), but it is best to protect plants from freezing weather by covering the bed with a portable plastic tunnel or row cover.
- Spinach will bolt in temperatures greater than 75°F (24°C). If the weather warms, try protecting spinach under shade cloth set over a frame.
Spinach Pests
- Spinach can be attacked by aphids, flea beetles, leafminers, slugs, and spider mites.
- Knock aphids off plants with a strong blast of water. Pinch out heavily infested foliage.
- Remove leaves in which leafminers are tunneling-. Look for the eggs on the underside of the leaves. Floating row covers can exclude leafminer flies from the planting bed.
- Spray flea beetles and spider mites with spinosad.
- Keep slugs and snails away from spinach by sprinkling a barrier of diatomaceous earth around plants.
More on pests and diseases: Spinach Growing Problems: Troubleshooting.
Spinach Diseases
- Spinach is susceptible to mildew, rust, and mosaic virus.
- Plant rust and disease-resistant varieties.
- Mildew and rust are fungal diseases. Spray-mist leaves with compost tea to prevent fungal diseases.
- Plants hit by mosaic virus should be removed from the garden. Mosaic virus will cause leaves to be mottled or streaked white or yellow.
- Keep the garden clean of debris. Remove and destroy diseased plants.
Harvesting Spinach
- Spinach leaves can be harvested as soon as they are big enough to eat.
- Cut leaves 4 to 7 inches (10-17cm) long from plants that have 6 to 8 leaves. Cut the older outer leaves first. Allow the remaining young leaves to grow on to maturity.
- If you harvest all of the leaves from a plant, cut the leaves 3 inches (7cm) above the soil; new leaves will grow on for a second harvest.
- Very large leaves and older leaves can be bitter; harvest leaves sooner rather than later.
- Lengthening days (days longer than 14 hours) and warming weather (temperatures greater than 75°F/24°C) will cause spinach to bolt, flower, and set seed. Bolting will mark the end of the harvest.
Storing and Preserving Spinach
- Wash spinach thoroughly to eliminate the grit that sometimes sticks to crinkled leaves.
- Spinach can be refrigerated for up to one week.
- Spinach can be frozen canned or dried.
- Spinach seeds can be sprouted.
Spinach Varieties to Grow
- ‘America’ (52 days): mostly heat and drought tolerant.
- ‘Bloomsdale Long Standing’ (43 days): crinkled leaves, mosaic virus tolerant.
- ‘Giant Noble’ (45 days): resistant to mosaic virus.
- ‘Tyee’ (37-53 days): resistant to downy mildew.
Hot Weather Spinach Alternatives
- Malabar spinach: vigorous climbing vines; native to tropical Asia and Africa.
- New Zealand spinach: grows naturally as a trailing ground cover.
About Spinach
- Spinach is a cool-season annual grown for its leaves.
- Spinach forms a rosette of dark green leaves that can be flat or crinkled (savoy leaf spinach).
- Spinach is related to beets and Swiss chard.
- Botanical name: Spinacia oleracea
- Origin: Asia
Grow 80 vegetables: THE KITCHEN GARDEN GROWERS’ GUIDE
