Spinach

Choosing & planning

What is spinach and where does it grow best?

Spinach (Spinacia oleracea) is a hardy annual leafy green native to Persia (southwest Asia) that grows best in the cool weather of spring and fall. It is related to beets and Swiss chard and thrives in fertile, well-drained soil in full sun to partial shade at temperatures of 50°F–75°F.

What are the main types of spinach, and how do they differ?

There are four main types: savoy (curly, crinkled dark-green leaves — preferred for fresh eating, better flavor, longer shelf life, and less oxalic acid), semi-savoy (lightly crinkled, disease-resistant, easier to clean), smooth or flat-leaf (spade-shaped, faster-growing, preferred for canning and freezing), and baby-leaf (small tender leaves harvested early, ideal for salads and containers).

Which spinach varieties are recommended, and how do I choose one?

Widely recommended varieties include Bloomsdale (savoy, slow-bolting, 48–50 days), Melody (semi-savoy, downy mildew tolerant, 42 days), Tyee (semi-savoy, very slow-bolting, downy mildew resistant), and Olympia (smooth, fast-growing, slow-bolting, 46 days). For spring and summer, choose slow-bolting varieties; for fall and winter, use fast-growing vigorous types. Downy mildew resistance is a key trait to look for in all seasons.

What should I look for when buying spinach seeds or transplants?

Always use fresh seed each year — seed more than one year old germinates poorly. Check the seed packet for specific varietal recommendations. When buying transplants, select plants with 4–6 mature leaves and a well-developed root system, which typically requires 5–6 weeks of growth.

Can I grow spinach in my climate or hardiness zone?

Spinach is hardy and tolerates temperatures as low as 15°F–20°F without injury, making it suitable for most temperate climates. Well-established plants can overwinter in zones 8 and warmer with no protection; in colder zones, plants survive under heavy mulch or a cold frame. It is not suited to peak summer heat above 75°F.

Can I grow spinach in containers or pots, and what size do they need?

Spinach grows well in containers; choose a pot at least 24 inches in diameter filled with a rich, nutrient-dense potting mix. Terracotta and plastic pots both work. Select varieties suited to containers, such as ‘Baby’s Leaf’.

Can I grow spinach indoors or in a greenhouse?

Spinach can be started indoors 5–6 weeks before transplanting out when soil temperatures reach at least 40°F. In cold climates, cold frames, low tunnels of greenhouse plastic, or clear polypropylene row covers over raised beds function like a greenhouse to extend the season and encourage early leaf growth.

Starting from seed & propagation

Should I start spinach from seed or buy transplants?

Both are viable, but direct seeding is most common. Transplants provide an earlier harvest, though some growers find spinach does not respond well to indoor transplanting. If using transplants, plant them near the last frost-free date; direct-seeded spinach can go in 3–4 weeks earlier.

When should I start spinach seeds indoors?

Start spinach seeds indoors 5–6 weeks before the intended outdoor transplanting date. Transplants can go outdoors in most temperate areas in early March, as soon as soil temperatures reach 40°F.

How deep should I sow spinach seeds?

Sow spinach seeds ½ inch deep and firm the soil over them to ensure good seed-to-soil contact and germination.

What temperature do spinach seeds need to germinate?

Spinach seeds germinate best at soil temperatures of 45°F–68°F, with an optimum around 55°–65°F widely cited. Germination is significantly reduced above 80°F and inhibited above 85°F. Pre-soaking seeds in cold water in the refrigerator for 24–48 hours before planting can improve germination in marginally warm soils.

How long do spinach seeds take to germinate?

Spinach seeds typically emerge within 7–10 days under good conditions.

Site, soil & timing

How much sun does spinach need?

Spinach prefers full sun but tolerates partial shade, needing at least 4–6 hours of direct sunlight daily. It will still produce a respectable harvest with less. In late spring or summer, some afternoon shade can delay bolting.

What type of soil does spinach prefer?

Spinach grows best in fertile, well-drained sandy loam rich in organic matter. It is sensitive to saturated or waterlogged soil conditions and does poorly in heavy clay without amendment.

What soil pH does spinach need?

Spinach requires a soil pH of 6.0–7.0; most sources cite 6.0–6.5 as ideal. It is sensitive to acidic soils below 6.0, and lime should be incorporated at least 3 months before planting if correction is needed.

How should I prepare and amend the soil for spinach?

Amend the planting bed with rich compost or aged manure, then loosen the soil 12–18 inches deep to accommodate spinach’s long taproot. Work pre-plant fertilizer into the top 6 inches based on soil test results, and apply no more than 1 inch of compost per 100 square feet. Mixing 3 inches of aged compost into the top 6 inches of existing soil is a practical approach.

When should I plant spinach outdoors?

Plant spinach 4–8 weeks before the average last frost date in spring, and 6–8 weeks before the average first frost in fall. Seeds can go in as soon as soil temperatures reach 40°F; transplants should be planted near the last frost-free date. Two crops per year are achievable with this spring-and-fall timing.

Does spinach tolerate frost, heat, or drought?

Spinach tolerates frost well — established plants survive temperatures as low as 15°F–20°F — but is highly sensitive to heat above 75°F and to days longer than 14 hours, both of which trigger bolting and leaf bitterness. Drought also triggers bolting, so consistent soil moisture is essential. Young seedlings and fully mature plants are more vulnerable to hard freezes than intermediate-sized plants.

Planting

How far apart should I space spinach plants?

Thin or space spinach plants 3–6 inches apart within the row, allowing leaves to reach full size; some programs recommend 12 inches when growing to maximum size. Failure to thin to at least 4 inches can cause stunted growth and premature bolting.

How far apart should the rows be?

Space rows 12–18 inches apart for typical home garden plantings, though 1–3 feet between rows is also used in larger-scale settings.

How deep should I plant spinach?

Sow spinach seeds ½ inch deep. When transplanting seedlings, plant them in holes dug to the same size as the existing root ball.

Are there special planting techniques for spinach?

Pre-soaking seeds in cold water in the refrigerator for 24–48 hours before planting significantly improves germination. In heavy or moisture-retaining soils, using raised beds with the ridge-and-furrow method helps prevent seedling diseases. Raised beds also warm up faster in spring, enabling earlier planting.

What grows well next to spinach (companion plants)?

Alliums (onions, garlic, leeks) deter aphids, beetles, and deer with their strong scents while attracting beneficial parasitic wasps and ladybugs. Brassicas (broccoli, cabbage, cauliflower) are good companions because their root systems occupy different soil layers, avoiding nutrient competition; radishes used as a trap crop lure leaf miners away. Carrots, lettuce, and strawberries are also recommended companions.

Watering

How much and how often should I water spinach?

Water spinach regularly, supplying 1–2 inches per week. Consistent moisture is critical — fluctuations cause leaves to become tough, slow leaf development, and produce off-flavors.

What is the best way to water spinach?

Water the soil rather than the leaves, as moisture on leaves encourages fungal diseases. A soaker hose delivers consistent moisture without wetting the foliage.

What are the signs of over- or under-watering spinach?

Under-watering causes spinach to bolt (send up a central flower stalk), turning leaves bitter and inedible. Moisture fluctuations lead to tough leaves, slow development, and off-flavors. Saturated or waterlogged soil encourages root diseases and damping-off of seedlings.

Should I mulch spinach, and with what?

Yes — apply a 2–3-inch layer of organic mulch such as hay, straw, grass clippings, or coarse compost after fertilizing to conserve moisture, suppress weeds, and protect plants from hard freezes.

Feeding & fertilizing

How should I fertilize spinach?

Side-dress with a nitrogen fertilizer 2–4 weeks after thinning or transplanting: apply ½ cup of high-nitrogen fertilizer (e.g., 21-0-0) per 35 feet of row, or 1 pound of calcium nitrate (15.5-0-0) per 100 square feet. Place fertilizer 4–6 inches away from plants to avoid root burn, then water it in.

What fertilizer or nutrients does spinach need?

Spinach is a nitrogen-hungry crop; high-nitrogen fertilizers such as calcium nitrate (15.5-0-0) or ammonium sulfate (21-0-0) are commonly used for side-dressing. Pre-plant compost and balanced fertilizer incorporated into the soil based on a soil test will meet broader nutrient needs. Feed regularly with a water-soluble plant food for the most tender and rapid leaf production.

When and how often should I feed spinach?

Incorporate pre-plant fertilizer and compost at planting. Side-dress with nitrogen 2–4 weeks after thinning or transplanting. Container-grown spinach planted with a slow-release fertilizer at the time of planting may need no further fertilization during the season.

Pests

What pests commonly attack spinach?

Common spinach pests include aphids, flea beetles, spider mites, caterpillars (including armyworms), and Lygus bugs. Aphids are among the most frequent, feeding in colonies on leaves and producing sticky honeydew that promotes sooty mold growth.

How do I identify spinach pest damage?

Aphid colonies appear as small pear-shaped yellow, green, or dark insects on leaf undersides; infested leaves turn yellow, wilt, or show water-stress symptoms, with sticky honeydew deposits visible. Armyworm larvae cause irregular holes or skeletonized leaves, and egg clusters of 50–150 eggs may be present on foliage.

How do I prevent spinach pests?

Encourage natural enemies — ladybird beetles, lacewings, syrphid fly larvae, and parasitic wasps — by avoiding broad-spectrum insecticides. Planting alliums (onions, garlic) nearby repels aphids and beetles and attracts beneficial insects.

How do I control spinach pests organically and chemically?

Organically, hand-wipe infested leaves, wash aphids off with a strong stream of water, and control honeydew-feeding ants that protect aphid colonies. Insecticidal soaps applied with thorough coverage of all leaf surfaces — including undersides — are effective but may require more than one application; check the label for the pre-harvest interval.

Diseases

What diseases commonly affect spinach?

Common spinach diseases include downy mildew (blue mold), anthracnose, Fusarium wilt, Verticillium wilt, damping-off (caused by Pythium, Rhizoctonia, Aphanomyces, and Fusarium), Stemphylium leaf spot, Cladosporium leaf spot, and white rust. Viral diseases such as spinach blight (cucumber mosaic virus) and curly top (beet curly top virus) also occur.

How do I recognize spinach disease symptoms?

Downy mildew shows as yellow spots on upper leaf surfaces with purple fungal growth on undersides, causing curled or distorted leaves in severe cases. Anthracnose and leaf spots appear as water-soaked spots that enlarge into tan or brown papery lesions. Fusarium wilt causes yellowing of older leaves, premature plant death, and dark discoloration of the vascular system. White rust produces yellow spots on upper surfaces and white blister-like pustules on leaf undersides.

How do I prevent spinach diseases?

Water the soil rather than the leaves to reduce leaf wetness and fungal disease risk. Choose disease-resistant varieties such as downy mildew-resistant ‘Tyee’ or ‘Olympia’. Use raised beds about 3 inches high to improve drainage and reduce damping-off. Avoid planting in areas with a known history of disease problems.

Disorders & troubleshooting

What physiological disorders affect spinach (such as blossom-end rot, cracking, or sunscald)?

Documented spinach disorders include heart-leaf disorder, leaf necrosis and scorch, tip burn, and nutritional yellows. These result from environmental and nutritional factors rather than pathogens.

What causes these disorders and how do I prevent them?

Heart-leaf disorder is associated with low light, wide diurnal air temperature fluctuations, and low soil temperatures. Leaf necrosis and scorch are linked to ozone and other air pollutants. Nutritional yellows result from nutrient disorders, which can be addressed through proper soil testing and fertilization.

Why are my spinach leaves yellowing, curling, or spotted?

Yellowing with mosaic patterns, ringspots, or puckered and distorted leaves typically indicates viral infection (spinach blight or mosaic viruses) transmitted by aphids and thrips. Yellow spots with tan centers and purple fungal growth on leaf undersides indicate downy mildew. Aphid feeding alone also causes general yellowing and wilting.

Why is my spinach not growing or producing well?

The most common cause is planting too late in spring when temperatures are already too warm — many gardeners miss the cool-season window entirely. Failure to thin seedlings to at least 4–6 inches apart causes stunted growth and premature bolting, as does dry soil. High summer temperatures above 75°F reduce growth and quality and cause plants to flower prematurely.

Harvest

How long does spinach take to mature?

Depending on variety, spinach reaches full maturity in approximately 30–50 days from seeding. Fast baby-leaf varieties like ‘Tragopan’ and ‘Space’ are ready in 24–25 days, while Bloomsdale Longstanding takes 48–50 days. From transplants, harvest comes sooner than from direct seeding.

How do I know when spinach is ready to harvest?

Harvest when leaves have reached full size and are vibrant green and crisp. Baby-leaf spinach is ready when leaves are 3–4 inches long. Harvest before the plant shows any sign of bolting (an elongated central stem), as leaves become bitter after the plant flowers.

How do I harvest spinach correctly?

Pick the outermost, oldest leaves first using a clean knife or scissors, working inward so younger leaves continue developing. You can also cut the entire plant at the base for a full harvest all at once. Wash and refrigerate or prepare leaves immediately after picking.

How often should I harvest spinach?

Harvest frequently — regular picking stimulates new tender leaf growth and extends the productive life of the plant.

Storage, preservation & seed saving

How should I store fresh spinach, and how long does it keep?

Wrap fresh spinach in a paper towel to absorb excess moisture, seal in a container or bag, and store in the refrigerator crisper drawer for up to 10 days. Fresh purchased spinach should ideally be used within one week. Keep spinach away from ethylene-producing fruits like apples and bananas, which accelerate spoilage.

How can I preserve spinach (canning, freezing, or drying)?

To freeze, water-blanch spinach for 2 minutes, plunge into ice water for 2 minutes, drain, package with ½-inch headspace, and use within one year. To dehydrate, spread in a single layer and dry at 125°F for 4–10 hours until crisp, then store in sealed containers. Pressure canning requires processing pints for 70 minutes and quarts for 90 minutes at 11 PSI on a dial-gauge canner at 0–2,000 ft elevation.

Uses & nutrition

What is spinach commonly used for in cooking?

Spinach is eaten raw in salads and smoothies or cooked in soups, pasta, stir-fries, pizza, fritters, quiches, breakfast scrambles, and pesto. Young tender leaves are best raw while mature leaves stand up better to heat. Frozen spinach works well in soups, sauces, casseroles, and stir-fries.

What are the nutritional benefits of spinach?

Spinach is rich in iron, calcium, potassium, magnesium, vitamins A, B6, B9, C, E, and K, and antioxidants including lutein. One cup of cooked spinach provides approximately 987% of the daily vitamin K requirement.

Season extension & regional growing

How can I extend the spinach growing season?

Use clear polypropylene row covers, low tunnels, or cold frames to protect plantings from frost and extend both the spring and fall harvest windows. In cold climates, fall-planted spinach can be mulched heavily and covered with greenhouse plastic all winter, resuming growth in early spring. Succession planting using slow-bolting varieties for spring and fast-growing types for fall stretches the harvest across multiple seasons.

Can I grow a fall or second crop of spinach?

Yes — two crops per year are achievable by planting 4–8 weeks before the last spring frost and again 6–8 weeks before the first fall frost. For fall, choose early-maturing cultivars and plant 50–75 days before the anticipated maturity date (about 1–2 weeks after first fall frost). Fall-planted spinach can overwinter and provide harvests for up to eight months in milder climates.

How do I grow spinach in a particularly hot or cold region?

In hot regions, choose slow-bolting varieties like ‘Olympia’ or ‘Indian Summer’, provide afternoon shade, and time plantings for cool seasons only; heat-tolerant substitutes like Malabar spinach (Basella alba) and New Zealand spinach (Tetragonia tetragonioides) can be grown through summer. In cold regions, mulch established plants heavily and protect with a cold frame or low tunnel; overwintered plants with 4–5 true leaves resume growth in spring, and zones 8 and warmer can grow spinach through winter without any protection.