Vegetable · Amaranthaceae
Spinach
Spinacia oleracea
Plant it cool, water it steady, and pick it young, and spinach hands you tender leaves in barely six weeks.
Full sun
Every 2–4 days
32–77°F · 0–25°C
40–50 days
Overview
Spinach is a fast, cool-weather leafy green that thrives in the shoulders of the year. It runs from seed to a full picking of tender leaves in about 40 to 50 days, which makes it one of the first things you can harvest in spring and one of the last in fall. Crowd it into the warm middle of summer, though, and it bolts almost overnight.
The plant stays low and compact, reaching only 6 to 12 inches (15 to 30 cm) across, so it slips into a garden corner, a raised bed, or a roomy container with no trouble. You eat the leaves, harvesting the outer ones first and letting the center keep on growing. That cut-and-come-again habit stretches a single sowing across several weeks.
Beyond the kitchen, spinach earns its high-oxalate reputation honestly. The leaves are a healthy green for people, but those same oxalates make it a green to feed pets and livestock in moderation rather than by the bowlful.
Care
The short version: sow spinach in the cool of spring or fall, give it full sun to partial shade and rich, moist soil, and pick the outer leaves often before warm weather pushes it to bolt.
Light
Spinach grows well in full sun during the cool months but takes partial shade in stride. Once the weather warms, a little afternoon shade is a help rather than a hindrance, since it slows the bolting that heat brings on.
Water
Keep the soil evenly moist and check it every few days, since spinach has shallow roots and tender leaves that wilt fast. Steady moisture grows lush foliage and buys you a few extra weeks before the plant bolts in warming weather.
Soil
Plant in rich, well-drained soil loaded with organic matter. Spinach is easygoing about pH, taking anything from 6.0 to 7.5, but it rewards a bed dug full of compost with fuller, faster leaf growth.
Temperature
Cool weather is the whole game. Spinach holds up from near freezing to about 77°F (25°C), and it does its best growing on the lower end of that, which is why spring and fall plantings beat a summer crop every time.
Humidity
Ordinary outdoor humidity suits spinach fine, so there's no number to chase. Airflow is what counts here, because crowded, damp leaves are exactly what downy mildew needs to take hold.
Feeding
Spinach is a heavy feeder that wants nitrogen to push out leaf after leaf. Work compost or a balanced, nitrogen-rich fertilizer into the bed before planting, then side-dress through the season if the leaves start to pale.
Pruning
There's no real pruning to do. Just harvest the outer leaves as they size up and the center keeps producing, and pull off any leaves that yellow or any growth that starts to bolt.
Repotting
Spinach is grown as an annual and rarely outlives a single season, so it isn't repotted. When a planting is spent, clear it out and re-sow rather than trying to move plants on.
Size & spacing
Plants stay small at 6 to 12 inches (15 to 30 cm) tall and about as wide. Thin seedlings to 3 to 6 inches apart so each one has room for air to move and leaves to fill out.
When to plant
Spinach is built for cold and runs from heat. Sow it as soon as the spring soil is workable, then sow again in late summer for a fall crop, and pick the leaves through the cool weeks before the plants bolt.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Usually direct-sown; optionally start 4-6 weeks before the last spring frost if transplanting.
- Plant: Early spring as soon as soil is workable (about 4-6 weeks before last frost) once soil reaches 45°F, and again in late summer for a fall crop.
- Harvest: Harvest leaves roughly 40-50 days after sowing, before plants bolt; grown for foliage rather than bloom.
Hardiness
USDA hardiness zones: 2–11
Temperature: down to -46°C
Troubleshooting
Spinach trouble usually shows up on the leaves or as a sudden rush to flower. Catch these early and you can still get a good picking off the plant. Match what you see below, then act before the crop turns bitter or the disease spreads.
Yellow patches on top, fuzzy mold underneath
This is downy mildew, a fast-moving disease that takes hold in cool, wet, crowded plantings. The telltale sign is gray to violet fuzz on the leaf undersides matched to yellow blotches above. Strip out infected leaves, open the planting up for airflow, and water at the base in the morning so the foliage dries fast.
Fix:
- Remove and destroy infected leaves and plants
- Improve air circulation and avoid overhead watering
A flower stalk shoots up and the leaves turn bitter
This is bolting, and it kicks in once the days lengthen and the weather warms. The plant switches from making leaves to making seed, and the foliage it does keep grows small and harsh-tasting. Pull the whole plant the moment a central stalk appears, then sow a fresh batch in cooler conditions.
Fix:
- Harvest the entire plant promptly once bolting begins
- Remove bolted plants and sow a fresh cool-season planting
Pale winding tunnels traced inside the leaves
These trails are the work of leafminer larvae feeding between the upper and lower leaf surfaces, where no spray can reach them. Pick off and bin any mined leaves as soon as you spot them. A floating row cover keeps the egg-laying flies off the crop in the first place.
Fix:
- Pick off and destroy mined leaves
- Remove badly infested plants
Toxicity
Spinach is a wholesome edible green and is not a poisonous plant. The one thing to watch is its high oxalate content, which is a dietary footnote for people prone to kidney stones and a reason to feed it to cats, dogs, and horses only in small amounts rather than large servings.
Toxic to
Cats · Dogs · Horses
Safe for
People · Rabbits · Livestock · Birds — the leaves
Cats Caution
A nibble of spinach won't harm a cat, but the leaves are high in soluble oxalates. A steady diet or a large helping can stress the kidneys and upset the stomach, so keep it to the occasional small taste.
Dogs Caution
Small amounts are fine for most dogs, though the oxalates add up. Big or frequent servings can irritate the gut and tax the kidneys over time, which matters most for dogs already prone to kidney trouble.
Horses Caution
Spinach is not a poison to horses, but the high oxalate load can interfere with calcium and burden the kidneys when fed in quantity. A handful now and then is the safe limit.
Rabbits Safe
Rabbits can eat spinach as part of a mixed green diet. Because of its oxalates, rotate it with other leafy greens rather than feeding it every day.
Livestock Safe
Cattle, goats, and sheep tolerate spinach and its trimmings in moderation, and the leaves carry no toxin that puts a grazing animal at risk.
Birds Safe
Backyard hens and pet birds peck at spinach happily. Offer it as one green among several so the oxalates never make up the bulk of the diet.
People Edible
Spinach is a wholesome leafy green eaten raw or cooked. It is naturally high in oxalates, which only matters for anyone prone to kidney stones, and cooking brings those levels down.
Spinach is high in oxalates, a human dietary consideration (relevant to kidney-stone-prone individuals); cooking reduces oxalate levels.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
Most spinach falls into savoy, semi-savoy, or smooth-leaf types, and a few well-tested varieties cover most gardens. These are the ones worth knowing by name.
Bloomsdale Long Standing
An heirloom savoy with thick, heavily crinkled dark-green leaves that holds up well to cold.
Tyee
A semi-savoy hybrid that resists bolting in the heat and is ready to pick in about 45 days.
Melody
A 1977 All-America Selections winner with lightly crinkled leaves, fine flavor, and slow bolting.
Companions
Spinach grows best alongside other cool-season crops, especially legumes that share its early timing and feed nitrogen back into the bed.
Plant near
Peas: Shares cool-season preferences and the legume fixes nitrogen, making it an efficient early-spring interplant.
Bush beans: Listed on cool-season interplanting guides as a compatible companion that supplies nitrogen.
Brassicas: Cool-season brassicas pair well with spinach for interplanting in spring and fall beds.
How to propagate
Spinach is one of the simplest greens to grow from scratch, sown straight into the ground without any fuss over transplants.
SeedEasy
Direct sow in early spring once soil reaches about 45°F and again in late summer for fall. · Germinates in about 7-14 days; harvestable in roughly 40-50 days.
Spinach is almost always grown straight from seed in the ground. Sow the seeds 1/4 to 1/2 inch deep once the soil hits about 45°F (7°C), then thin the seedlings to 3 to 6 inches apart. They sprout in 7 to 14 days and give you pickable leaves in roughly 40 to 50 days.
Myths
Spinach is an exceptionally rich, easily absorbed source of iron.
Spinach does carry iron, but it's the non-heme kind, and the leaf's own oxalates lock up much of it in the gut. It is a far weaker iron source than the Popeye legend suggests, so lean on it for other nutrients instead.
Spinach needs full sun all day to grow well.
It does fine in full sun but takes partial shade in stride. A little afternoon shade actually helps in hot weather by holding off the bolting that heat brings on.