Melon

• Seeds germinate in six to nine days.

Sowing time

Melon seedlings grow a little more slowly than cucumbers. You can sow them up to two months before the last frost date – I used to do that, with marginal gain.

Now I sow four to six weeks before the last frost, when conditions under cover are warmer and brighter.

Sowing method

Lay seeds flat on top of compost in the module cell, one per cell, then push in slightly and add a little compost on top. Water fully so the compost is totally moist.

Trays need to be in constant warmth for the first week, above 21 °C/70 °F for best results. Once you see the first small green shoots, they need light.

They can be a little less warm after the germination phase, though always above about 13 °C/55 °F for strongest growth.

Pot on?

After four to five weeks, you probably need to transfer your module seedlings to 7 cm/3 in pots. A further potting on is not necessary, unless either the ground is not ready or it’s not warm enough to transplant.

• TOP TIP: As with cucumber plants, do not overwater your melons in modules and pots. Compost that is half dry is fine, and better than it being fully saturated all of the time.

Transplant size and time

See the photos above to give you the best idea of how plants need to be a fair size. A week or two beyond the last frost date is good for transplanting, so that soil and temperatures have warmed to a good level.

Transplant method

Use a trowel to make a hole slightly larger than the pot, and 5 cm/2 in deeper than the pot is high, to bury some of the lower stem. This is to have a sturdy plant on a stronger stem.

Spacing

45 cm/8 in is possible, but 60 cm/24 in is better, for leaves to have full access to light in order to grow sweeter fruits.

Support and pruning

Melon stems trail on the ground in the same way as squash. They also grow well as cordon plants, with a string in the hole before transplanting when you are growing them under cover. Exactly as for tomatoes and cucumbers.

Then the differences are in sideshooting. With cucumbers you remove all sideshoots, but with melons this would not work because the fruits grow and develop on the first node (where a leaf leaves the stem) of any sideshoot. Melons do not develop on the main stem but that is what most cucumbers do.

1. Remove all sideshoots until plants are at least 1 m/39 in tall.
2. Above this height, allow sideshoots to develop, watch for fruit growing on them and then pinch out the leading point beyond a melon, leaving one melon per stem of sideshoot.
3. Plants do their own fruit pruning, so you notice little fruits rotting after several have set. If you want to limit any melon plant to a certain number of fruits, just keep pinching out new sideshoots, once the plant has your desired number of melons.

Four or five melons per plant ensures that ripening will happen more quickly than when there are larger numbers. In the photo above, you see an exceptional 12 Minnesota midgets on one plant, which amazed me. They did ripen eventually, in mid-September, and were mostly sweet too. I was lucky that early autumn was warmer than usual.

Under cover, water two or three times a week and increase the amount once you see melons developing and swelling. Then decrease watering once they are mostly full-grown and starting to ripen.

The rate of growth is a little slower than with cucumbers, so the total amount of water needed is not quite so much, but still a decent amount.

Extra mulch to retain moisture?

Worthwhile in dry climates. Commercial growers use clear polythene on soil for outdoor melons, which does not control weeds but warms the soil and retains moisture. Under cover, any undecomposed material is good on the surface, but in cool climates use only compost: a dark surface warms more readily than a light one.

How to judge readiness

Melons are the most fruit-like of all vegetables in this course, and probably of all that we grow. As a result, they have some fruity characteristics, of which one is a scent of ripeness.

• It’s such a lovely moment in late summer when the first aroma of ripe melon fills the air, often a long way from where they are ripening – this is your first clue.
• Before that, you may notice some cracking of the skin where a stalk joins the melon. That is also a sign of ripeness.
• Another is any change of colour, to more yellow than previously.
• And the skin will feel softer.

Watermelons are different because their skins do not soften, nor do they give us any lovely scent. The best clue of ripeness is to look at the little green pigtail of coiled tendril that comes out of the stalk of each fruit. Once this is changing from green to brown, the watermelon is ripe. (Thanks to Katja in Slovenia for this tip.)

How to pick

Simply cut the stalk with a sharp knife, while holding the melon in your other hand.

When fully ripe, a stalk easily detaches from the fruit, which is fine unless you want to store the melon for a few days because it now has an open wound.

• This may be why it’s sometimes recommended to support melon fruits with a net. It’s not that the stalk is too weak to retain its melon securely, more that, once ripe, they risk falling off unless you check them every day at this point.

When to pick and storing

Picking at any time of day is good. If you pick melons before they are fully ripe, they continue to ripen in the kitchen or anywhere with ambient warmth. A slightly unripe melon has firmer flesh, with more and pleasing acidity compared to a fully ripe fruit. You have choices.

• Pick before fully ripe if you want to keep them for longer before eating, and to avoid fruits falling off cordon plants.
• Fully sweet melons are attractive to ants. This can be quite an issue with melons ripening on the ground on trailing plants; watch for first signs of ripeness and pick immediately.

Watermelons are good to eat for a month or more after picking at the ripe stage.

Saving seed

Different varieties will cross-pollinate if growing nearby. It’s difficult to put a number on this distance because it depends how many obstacles are in the way and how many insects are flying.

• One method is to grow just one variety in a designated space. I use the greenhouse, and grow one variety of melon and one variety of watermelon. They can ripen as normal and you wash plus dry seeds after separating them from the fruit, which you eat as normal.
• Musk melons and inodorus (honeydew etc.) melons can cross-pollinate between the two types, being of the same species. As it happens this gives a nice result: Galia melons, with textured skin and pale green flesh.
• Watermelons do not cross with the other melons listed here

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Aphids are common in spring, until predators arrive. I give a little extra water when I see them, preferably in a way that washes many of them off the undersides of leaves. This reduces damage until ladybirds, hoverflies etc. arrive in early summer.

See the photos below of aphids on pepper plants, and how they recovered in summer.

Red spider mite (Tetranychus urticae)

These may multiply quickly in early summer and are then hard to control.

You can buy predator insects (Phytoseiulus persimilis). Order by mid-spring and they are delivered by post, on leaves which also have a few red spider mites. Place them on melon leaves, following which a balance of pest and predator establishes for several plants, through the whole summer.

• The predators are expensive and they don’t survive winter!
• One purchase of predators can suffice for melon and cucumber plants growing in the same structure under cover.

As with so many pests and diseases, the best cure is prevention. I find that well-composted, no dig soil grows plants with less likelihood of spider mites.

Disease

Downy mildew (Peronospora sparsa) thrives in damp conditions and on cooler nights, towards the end of a damp summer. You first notice yellow areas on leaves, which turn brown as the mildew takes hold. Removing damaged leaves can slow down the progress of the disease but is unlikely to stop it. Infected plants may die in three weeks unless dry sunshine returns, and the fruits are unlikely to be sweet.

• When watering after midsummer, don’t wet leaves.

Plants with a big infection of downy mildew are best removed to the compost heap. It’s safe to compost them.