Cucurbit (dessert fruit)
How to grow melons
Cucumis melo
Melons need more heat than any other cucurbit grown in Britain, so grow them in a greenhouse, polytunnel or cold frame. Sow at 20 to 25 °C from mid April, plant on a low mound in late May and train the shoots up strings or flat across the frame. Success depends on warmth, hand-pollinating four female flowers on the same morning, and easing off the water as the fruits ripen.
- Hardiness
- Tender, needs 20°C+ to set fruit
- Position
- Full sun, under glass or very warm
- Soil
- Rich, free-draining
- Ideal pH
- 6.0 to 6.8
- Water
- High until fruits size up, then reduce as they ripen
- Feeding
- Heavy feeder
Sowing and planting melons
WhenSow Apr to May with heat; plant out under glass late May; harvest Aug to Sep
Starting off
Sow indoors mid April to May, one seed on its edge 1 to 2 cm deep in a 9 cm pot at 20 to 25 °C, germinating in 5 to 8 days; grow on at 18 °C and plant under glass in late May. Pinch the tip at 5 leaves, keep 4 side shoots and hand-pollinate 4 female flowers on one morning so the fruits swell together.
Spacing and planting
Plant 60 cm apart in a greenhouse border or one per 25 to 30 cm pot or growbag, trained up strings or a trellis with each fruit in a net; in a cold frame plant one per frame, trained flat. Plant on a mound with the stem at pot depth, never deeper. One plant crops in a 30 cm pot under glass.
Varieties worth growing
- Sweetheart F1
- Cantaloupe with salmon-orange flesh that sets and ripens in cooler conditions than most. The first choice for a cold frame.
- Emir F1
- Galia type with netted skin and green flesh, bred to cope with cool nights in an unheated greenhouse.
- Ogen
- Small, green-fleshed, very sweet fruit of about 500 g on a compact plant that suits a frame.
- Alvaro F1
- Early Charentais type with orange, scented flesh; quick enough to ripen under a cloche in the south.
- Blenheim Orange
- Old greenhouse variety with netted skin and richly flavoured orange flesh. Needs the heat of a greenhouse.
Melons month by month
Timings are for central England. Allow two weeks later in the north and on cold, heavy soil.
- January
Nothing to do.
- February
Order seed. Wash the greenhouse glass so spring light is not wasted.
- March
Nothing to do. Sowing now only gives leggy plants with nowhere warm to go.
- April
Sow from mid April at 20 to 25 °C, one seed on edge per 9 cm pot.
- May
Grow on at 18 °C. Plant in the greenhouse in late May. Put the cold frame lid on to warm the soil.
- June
Plant in the cold frame in early June. Pinch out the tip at five leaves and train four side shoots.
- July
Hand-pollinate four female flowers on one morning. Open frames by day for insects. Start potash once the fruits are swelling.
- August
Support each fruit in a net. Stop the shoots two leaves beyond a fruit. Cut back the watering as fruits scent and ripen.
- September
Pick the last fruits. Close vents and frames early in the afternoon to hold heat.
- October
Clear the plants and compost them. Empty pots and growbags.
- November
Nothing to do.
- December
Nothing to do.
Feeding melons
A rich compost to start, one dry top-dress while the plant builds its frame, then potash from fruit set and nothing once ripening begins. Feeding a ripening melon dilutes the flavour.
A balanced feed, then high-potassium as the fruits swell; it needs warmth.
Feeding plan
Planting, late May: pots and growbags
Fruit & Vegetable Fertiliser 4-5-6
5 g per litre of compost mixed in at potting: 75 g for a 30 cm pot holding about 15 litres.
Planting, late May: greenhouse border or cold frame
Fruit & Vegetable Fertiliser 4-5-6
100 g/m² forked in with a bucket of garden compost per plant. At 60 cm spacing that is roughly 35 g per plant.
Three weeks after planting, mid June, once
Fruit & Vegetable Fertiliser 4-5-6
Pots and growbags: 2 g per litre of pot volume as a top-dress, 30 g for a 15 litre pot, watered in. Border or frame: 50 g/m², about 18 g per plant at 60 cm spacing, watered in, which reaches the label's season limit of 150 g/m². The label gives no interval for top-dressing pots; one is enough here because potash takes over at fruit set.
Weekly from fruit set until the first fruit starts to scent
1 to 2 g per litre of water: 10 to 20 g in a 10 litre can.
Only if older leaves yellow between the veins
1 to 2 g per litre of water, every 2 to 3 weeks, using water at greenhouse temperature.
Signs to watch
Fruits that stop at golf-ball size and drop
Poor pollination or more than 4 fruits set, not nutrition
Hand-pollinate and thin
Older leaves yellow between the veins
Magnesium locked out by potash feeding or cold roots
Epsom salts spray and warm water
Fruit splitting
Heavy watering after a dry spell
Reduce water once fruits are full size
Pests, diseases and problems
Leaves speckled pale, then bronzed and dry, with fine webbing underneath
Red spider mite, which thrives in hot, dry air under glass
Damp down the greenhouse floor daily and mist the undersides of leaves until the fruits begin to ripen. Introduce the predatory mite Phytoseiulus as soon as the first speckling shows.
Stem turns brown and soft at soil level and the plant collapses
Stem and collar rot from water sitting round the base of the stem
Plant on a mound with the top of the root ball slightly proud, and water into a pot sunk beside the plant so the stem base stays dry. There is no saving an affected plant.
White powdery patches on leaves and stems
Powdery mildew, encouraged by dry compost and still air
Keep the roots evenly moist, open vents on warm days and remove the worst leaves.
Clouds of tiny white insects when the leaves are disturbed, sticky leaves below
Glasshouse whitefly
Hang yellow sticky traps to spot them early and introduce the parasitic wasp Encarsia while numbers are still low.
Leaves mottled and distorted, growth stunted
Cucumber mosaic virus carried in by aphids
Remove the plant, wash your hands and tools, and deal with aphids on other greenhouse crops.
Harvest and rotation
Harvest and storage
Pick in August to September when the fruit smells sweet at the stalk end, the skin between the netting yellows and the end gives slightly under thumb pressure, 14 to 16 weeks from sowing. Cut with 2 cm of stalk and limit to 3 to 4 fruits per plant, 0.5 to 1 kg each. Ripen on a windowsill for 2 days if needed; eat within a week.
Rotation and companions
Rotation: cucurbit group with cucumber, courgette and squash, 3-year gap outdoors; fresh growbags or compost in the greenhouse each year.
Good to knowBest under glass in the UK; support fruits in nets and reduce watering as they ripen to concentrate the sweetness.
Growing melons in pots
Pots are the normal way to grow a melon under glass. Use one plant per 30 cm pot, about 15 litres, or one to a growbag, in fresh multipurpose or loam-based compost each year. Set the plant on a slight mound so water runs away from the stem, and tie the main shoots to strings or canes fixed to the greenhouse frame. Water with tepid water whenever the top few centimetres dry out, daily in midsummer, and keep the compost evenly moist until the fruits are full size. Then reduce watering so the compost is just moist. Support every fruit in a net tied to the frame, not to the plant.
Melons: common questions
Can you grow melons outside in the UK?
Only in the warmest southern gardens, and even there under a cloche or frame for most of the season. In the open, a normal British summer does not give the steady 20 °C melons need to set and ripen fruit. A cold frame, polytunnel or unheated greenhouse makes the crop reliable; choose Sweetheart, Emir or Alvaro.
Do melons need to be pollinated by hand?
Under glass, yes. Few insects find the flowers, so pick a male flower, remove the petals and press it into each female flower, the ones with a small swelling behind them. Do four on the same morning so the fruits develop together; if one sets days ahead it takes all the plant's energy and the rest drop.
How many melons will one plant produce?
Three or four good fruits of 0.5 to 1 kg each is a full crop for a plant in a pot or border. Remove any further fruitlets as they form. Leaving more gives small melons that fail to ripen before the autumn.
Sources
Growing information on this page was checked against these references in November 2026. Feeding rates are Dr Forest label rates.