How to grow melons

Melon seeds are widely available in garden centres and from online seed suppliers. Young plants may also be available in spring and early summer, from the same sources, although the choice of varieties will be limited. More vigorous grafted melon plants (see above) are also available from a few online veg seed/plant suppliers by mail order. Buying young plants is a good option if you only want one or two plants, or don’t have enough space, time or sufficiently warm conditions (18–21°C/64–70°F) to germinate seeds and raise young plants yourself. 

• You can plant melons in a greenhouse border, growing bag or large container, or in a large coldframe, from late May onwards, once the temperature stays reliably above 12–15°C (53–59°F)  
• Containers should be at least 45cm (18in) wide and deep, filled with peat-free multi-purpose potting compost. Position one plant in the centre, firming it in gently then watering generously  
• You can plant up to two melons in a standard growing bag 
• Before planting in a greenhouse border, add up to two bucketfuls of garden compost or well-rotted manure per square yard/metre, plus a modest amount of general purpose fertiliser such as Vitax Q4 or blood, fish and bonemeal. Space plants 45cm (18in) apart at the base of supports 

• Harden off melon plants carefully in a coldframe, mini-greenhouse or under cloches before planting out from early June, once you’re sure temperatures won’t drop below 12–15°C (53–59°F) at night
• Choose a very warm, sunny and sheltered planting site with fertile, free-draining soil. Then fork in up to two buckets of garden compost or well-rotted manure per square yard/metre, and add a light dressing of general purpose feed such as Vitax Q4 or blood, fish and bonemeal
• Warm the soil for several weeks ahead of planting by covering it with cloches or biodegradable membrane. Keep these in place after planting too. With biodegradable membrane, simply cut a hole in it at each planting point 
• Space plants at least 90cm (3ft) apart if trailing, and 45cm (18in) apart if growing up supports
• You could also try planting in growing bags or large containers at least 45cm (18in) wide and deep, positioned in a very warm, sunny courtyard or patio, although it may be tricky to produce fruit​
• Protect young plants from slugs and snails   

Melons are climbing or scrambling plants that can either be grown up supports or allowed to trail on the ground. Growing them vertically means they take up little ground space, which is particularly useful in a greenhouse. Suitable supports include sturdy bamboo canes, netting, vertical strings or trellis, which their tendrils can twine around. Melons can make large plants and the fruits can be heavy, so make sure the supports are strong and well anchored. Melon plants that trail on the ground can take up a lot of space, and are more vulnerable to slugs and snails, so take steps to protect young plants.

Decide how you want to train the stems from the start – there are several options. When growing vertically, you can have one main stem growing up the support, then train the side-shoots horizontally and pinch out the tips after seven to nine leaves have formed, to encourage flowering shoots to develop. Alternatively, once the young plant has five leaves, you can pinch out the growing tip to encourage side-shoots. When these appear, keep the four strongest and remove any others. These shoots can then be grown up supports or can trail on the ground. If growing in a large coldframe, arrange the four shoots in an X-shape. If growing under a long tunnel cloche, send two shoots in each direction.

It’s important to water melon plants regularly and consistently, especially when the fruits are starting to develop. You may need to water daily during hot weather. Aim to keep the soil or potting compost evenly moist but not saturated. Make sure water doesn’t sit around the base of the stem, as this could lead to rotting. When watering, avoid wetting the leaves, as that can encourage fungal diseases.

When growing melon plants vertically, lay a thick layer of garden compost or well-rotted manure over the root zone to hold in moisture and deter weeds. But leave a gap around the base of the stem, to avoid rotting. Alternatively, if the stems are trailing on the ground, consider covering the soil with biodegradable membrane. 

When the fruits are the size of walnuts, start feeding melon plants once a week with a high potassium liquid fertiliser. Stop feeding and reduce watering when the fruits start to ripen in late summer and the foliage dies back.

In a greenhouse, raise the humidity in hot weather by pouring a watering can over the paved or concrete flooring, so the water evaporates (known as damping down). High humidity also deters red spider mites and powdery mildew.

Greenhouses can get extremely hot in sunny weather, so put up shading if necessary to keep temperatures at 18–25°C (64–77°F) and avoid scorching the leaves. Increase the ventilation in hot weather too, by opening greenhouse doors and vents, as well as the ends of tunnel cloches and the roof of coldframes.

When growing under cover, melon flowers may need to be pollinated by hand. Alternatively open up tunnel cloches, coldframes and greenhouse doors and vents during the day to allow pollinating insects in. However, bear in mind that once one fruit starts to form, this can stop further fruits developing – to avoid this, you could keep the plants covered until several flowers are open, then ventilate to allow insects in. 

In a greenhouse or tunnel cloche, pollination can be poor even with vents open, so it’s often best to hand pollinate. Melons produce separate male and female flowers, so you need to transfer pollen from a male flower to a female flower for a fruit to develop. It’s easy to recognise a female flower, as it has a small fruitlet behind it, while male flowers do not. Pick off a fully open male flower and carefully remove the petals to expose the pollen-bearing anthers. Then gently press the male flower into the centre of open female flowers – one male flower will pollinate several female flowers. Alternatively you can use a small paint brush to transfer the pollen – gently dab the pollen from the centre of a male flower into the centre of up to four female flowers.

Limiting the number of melons per plant helps to ensure the fruits grow to a reasonable size and ripen well. When young fruit are the size of a gooseberry, select the best one or two on each side-shoot and remove all other flowers and fruit. Then pinch out the tip of each side-shoot two or three leaves beyond the fruits. Remove any new growth that forms beyond this point, so all the plant’s energy goes into the fruit.

Aim for four to six fruits on a greenhouse plant and up to four on an outdoor plant, which is usually the maximum number that will ripen by the end of the season. If the stems are trailing on the ground, place a tile or piece of wood under developing fruits to prevent discoloration or rotting. If the stems are climbing, you may need to provide extra support for the fruits as they swell and get heavier. Netting or hessian suspended from the supports, like a hammock, usually works well. Put cloches or fleece over outdoor plants by late summer, to keep them going as long as possible, so their fruits can ripen. Otherwise the plants will start to die as soon as night temperatures drop.

Support the developing fruits with a hammock of hessian or netting