Sweet pea care

Light

Sweet pea is a sun-lover and needs the brightest spot in the home to thrive. 6 hours of direct sun with cool roots; light shade in hottest part of the day. 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

Water sweet pea weekly deep watering. The actual day count varies with pot size, light level, and the season — the finger test (or, better, lifting the pot to feel its weight) is more reliable than a calendar. Empty any drainage saucer after watering so the pot is never sitting in water. Consistent moisture; mulch to keep roots cool.

Soil and pot

Sweet pea grows best in rich free-draining loam. Compost-rich; pH 7.0-7.5; alkaline preferred. 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

Sweet pea sits happiest at around 40-70% (outdoor) humidity and 10-21°C (50-70°F). Outdoor humidity rarely matters. If you keep the room above 10 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 sweet pea sparingly. Balanced feed at planting; high-potash feed every 2-3 weeks during flowering. 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 sweet pea in the Growli community. Each is annotated with the most common cause so you know where to start.

• Stops flowering in heat — Cool-season — stops above 24°C; deadhead daily to extend season.
• No flowers — Too rich soil or too much nitrogen; pinch tips early for branching.
• Aphids on tender tips — Rinse with water or use soap.
• Pollen beetle damage — Tolerable; rinse blooms before bringing indoors.
• Soggy stems at the base — Wet feet; improve drainage.

Companion plants

Sweet pea pairs well with Pansy, and Forget-me-not. These are species with similar light and water needs, so you can group them in the same room or on the same shelf and water as a batch.

Propagation

Direct-sow in autumn or early spring; soak seed overnight for faster germination. 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

Sweet pea is toxic to pets. ASPCA lists Lathyrus odoratus as toxic to cats, dogs, and horses. Seeds contain BAPN (β-aminopropionitrile) which causes lathyrism — weakness, paralysis, and seizures. Never confuse with edible peas. 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.

Sweet pea deep-dive guides

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

• Sweet pea watering schedule
• Sweet pea light requirements
• Best soil mix for sweet pea
• Sweet pea fertilizing guide
• When to repot sweet pea
• How to propagate sweet pea
• Sweet pea growth rate & size
• Sweet pea cold hardiness
• Sweet pea temperature & humidity
• Is sweet pea toxic to cats & dogs?
• Getting sweet pea to bloom

Related guides

Sweet pea is also commonly called annual sweet pea or garden sweet pea.

• Peace lily care — light, water and common problems
• Bird of paradise care — light, water and common problems
• Hoya care — light, water and common problems
• All 200 plant care guides in the Growli library