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Plant care

Spinach care

Spinacia oleracea

Also called true spinach, flat-leaf spinach, savoy spinach.

RHS H5USDA Grown as a cool-season annual in zones 3-11Pet-safeIndoor 15-25 cm tall

Watering rhythm

Direct sun (at least 4-6 hours)

2-3 cm per week

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Light

Direct sun (at least 4-6 hours)

Soil

Rich, well-drained loam

Humidity

40-70% (outdoor)

Temp

7-21°C

Pet safety

Pet-safe

Mature size

15-25 cm tall

Care at a glance

Light

Spinach needs sun on the leaves, not just bright ambient room light. Full sun in cool weather; afternoon shade in warmer months delays bolting. A south or west-facing windowsill in the northern hemisphere is the default; anywhere else, expect the plant to stretch and pale out within a season.

Watering

Outdoor spinach crops want 2-3 cm per week. The single best habit is a finger-test before watering — push a finger 3-4 cm into the soil. Damp = wait a day; dust-dry = water deeply at the base of the plant. Even moisture; mulch to keep roots cool and reduce bolting.

Soil and pot

Spinach grows best in rich, well-drained loam. Compost-rich; pH 6.5-7.0. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Spinach sits happiest at around 40-70% (outdoor) humidity and 7-21°C (45-70°F). Outdoor humidity rarely matters. If you keep the room above 7 year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed spinach sparingly. A nitrogen-leaning feed every 3-4 weeks while harvesting. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on spinach in the Growli community. Where a problem matches one of our diagnostic guides, click through for the full step-by-step recovery plan written for spinach specifically.

  • Bolting to flower — Heat and long days; sow in spring and autumn, not summer.
  • Yellow leaves — Nitrogen deficiency or downy mildew.
  • White or grey patches on leaves — Downy mildew; choose resistant varieties.
  • Leaf miners — Squiggly tracks inside leaves; remove affected leaves and cover with mesh.

Companion plants

Spinach pairs well with Strawberry, Pea, Lettuce, and Radish. These are species with similar light and water needs, so you can grow them in the same bed or container without conflict.

Propagation

Direct-sow seed in spring and autumn; spinach transplants poorly. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Spinach is pet-safe. Spinach is not listed as toxic by the ASPCA but contains oxalates that may aggravate kidney issues in some pets; small amounts are safe, large grazing is not advisable. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Spinach care — frequently asked questions

What is Spinach?

Spinach (Spinacia oleracea) is a edible crop with a low rosette annual growth habit, reaching 15-25 cm tall at maturity. Spinach is a cool-season leafy green that bolts quickly in heat. Best sown in early spring and autumn for tender leaves; New Zealand spinach (Tetragonia) substitutes well in hot summers.

How much light does spinach need?

Spinach grows best in direct sun (at least 4-6 hours). Full sun in cool weather; afternoon shade in warmer months delays bolting.

How often should I water spinach?

Water spinach 2-3 cm per week. Even moisture; mulch to keep roots cool and reduce bolting. The finger-test (or lifting the pot to feel its weight) beats a fixed weekly calendar because pot size, light, and season all change how fast the soil dries.

Is spinach toxic to cats and dogs?

Spinach is pet-safe. Spinach is not listed as toxic by the ASPCA but contains oxalates that may aggravate kidney issues in some pets; small amounts are safe, large grazing is not advisable.

What USDA hardiness zone does spinach grow in?

Spinach is rated for USDA zone Grown as a cool-season annual in zones 3-11 and RHS hardiness H5. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Spinach deep-dive guides

Every aspect of spinach care, each with its own calibrated guide:

Related guides

Spinach is also known as true spinach, flat-leaf spinach, and savoy spinach.