PlantSowGrow
How to grow Cleome (Colour Fountain)
Cleome hassleriana
Tall, exotic "spider flowers" in pink, violet and white with long whiskers, from midsummer to the frosts. Lightly scented and loved by bees.
At a glance: Sow early February to early March.
When to sow, plant and harvest
Timed for a typical UK garden (last frost mid-April). The app uses your own town's frost dates.
Growing Cleome (Colour Fountain): what it needs
- Light
- Full sun · 6+ hours a day
- Watering
- Water in dry spells; pots daily in summer
- Soil
- Any well-drained soil
- Spacing
- 45 cm
- Height
- 1.2 m
- In pots
- Grows well in containers
- Feeding
- Liquid feed every two weeks once flowering starts
- Hardiness
- USDA zones 2–11
- Difficulty
- Intermediate
Step by step
- Early February – early March · 10 weeks before the last spring frost
Sow Seeds Indoors
Sow in trays or modules of seed compost on a warm windowsill or in a propagator. Sow at 20–25°C; a few nights in the fridge first helps germination.
- 10–21 days after “Sow Seeds Indoors” · Mid February – late February
Check Germination
Seedlings should appear in 10–21 days. Keep the soil moist. If sown outdoors, thin them to 45 cm apart once they have two true leaves.
- 14–21 days after “Check Germination” · Late February – early March
Pot On Seedlings
When seedlings have two true leaves, move each into its own small pot or module, holding them by a leaf, not the stem.
- Late April · 11 days after the last spring frost
Harden Off
Stand plants outside by day and bring them in at night for 7–10 days so they get used to outdoor conditions.
- Early May – early June · 3 weeks after the last spring frost
Plant Out
Plant out 45 cm apart once frosts are over. Water in well.
- 14 days after “Plant Out” · Mid May
Add Support
Push in canes or twiggy sticks and tie in stems before they flop.
- 79–109 days after “Check Germination” · Mid May – mid June
First Flowers — Deadhead Regularly
Snip off faded flowers every few days to keep new ones coming for months. Take a photo for your journal!
- Mid October – early November · around the first autumn frost
Clear or Collect Seed
When frost blackens the plants, pull them up for the compost heap. Leave a few seedheads first if you want to save seed.
