Plant care

Squash (zucchini) care

Cucurbita pepo

Also called summer squash, zucchini, courgette.

Light

Squash is a sun-lover and needs the brightest spot in the home to thrive. 6-8 hours of direct sun. Indoors that almost always means a south or west-facing windowsill in the northern hemisphere. Plants moved abruptly from low light to direct sun will scorch — acclimate them over 7-10 days by giving a little more sun each day.

Watering

Outdoor squash crops want 2-3 cm of water per week as a deep weekly soak. The single best habit is a finger-test before watering — push a finger 3-4 cm into the soil. If it comes back damp, wait a day. If it comes back dust-dry, water deeply at the base of the plant. Squash wilts dramatically at midday in heat — water early morning at the soil line.

Soil and pot

Squash grows best in rich, well-drained loam. Compost-amended garden soil; pH 6.0-7.5. Containers must be very large (40 cm+). 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

Squash sits happiest at around 40-70% (outdoor) humidity and 18-29°C (65-85°F). Humid weather raises powdery mildew risk. If you keep the room above 18 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 squash sparingly. Balanced feed at planting and a side-dress of compost or a balanced liquid feed every 3 weeks. 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 squash 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 squash specifically.

Yellow leaves — Powdery mildew or squash vine borer damage.
Curling leaves — Squash bugs or virus.
Brown leaf spots — Powdery mildew or anthracnose.
Sudden wilting — Squash vine borer — check the stem base for sawdust-like frass.
Fruit rotting at the blossom end — Blossom-end rot from uneven watering.

Companion plants

Squash pairs well with Bean, Corn, and Marigold. 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 after the last spring frost when soil reaches 18°C, or start indoors 3-4 weeks earlier. 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

Squash is pet-safe. ASPCA lists Cucurbita pepo as non-toxic to cats and dogs. Bitter ornamental gourds are an exception. 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.

Squash care — frequently asked questions

What is the common name for Cucurbita pepo?

Cucurbita pepo is most commonly called Squash, but it is also known as summer squash, zucchini, courgette. The names refer to the same species, so care instructions for Squash apply identically to anything sold as zucchini.

How much light does squash need?

Squash grows best in direct sun (at least 4-6 hours). 6-8 hours of direct sun.

How often should I water squash?

Water squash 2-3 cm of water per week as a deep weekly soak. Squash wilts dramatically at midday in heat — water early morning at the soil line. 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 squash toxic to cats and dogs?

Squash is pet-safe. ASPCA lists Cucurbita pepo as non-toxic to cats and dogs. Bitter ornamental gourds are an exception.

What USDA hardiness zone does squash grow in?

Squash is rated for USDA zone Grown as an annual in zones 3-11 and RHS hardiness H1c. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Squash deep-dive guides

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

Related guides

Squash is also known as summer squash, zucchini, and courgette.