Melon Care: Watering, Feeding and Keeping the Fruit Off Wet Soil

Water heavily while the fruit fill, then stop

A melon plant's water needs change completely partway through the season, and treating it the same all summer is the commonest reason for a full-sized fruit with bland, watery flesh. While the vine is growing and the fruit are swelling, the plant needs a lot of water: a deep soak twice a week that wets the soil down eight to ten inches (20 to 25 cm), rather than a daily sprinkle that keeps the roots shallow and the plant permanently anxious.

In the last ten to fourteen days, when the fruit has reached full size and is no longer growing, cut back sharply. Water taken up at that stage goes straight into the flesh and dilutes the sugars that the leaves have spent two months making. A melon finished on the dry side is noticeably sweeter and firmer than the same fruit watered to the day it slipped, and gardeners who complain that their melons taste of cucumber are almost always watering to the end.

Water the soil, never the leaves. Wet foliage is how powdery and downy mildew get started, and splashed soil carries fungal spores onto the lower leaves within minutes.

Feed moderately, and switch to potassium at fruit set

Melons are hungry but they are easy to overfeed with nitrogen, and an overfed plant is obvious: enormous dark leaves, runners racing across the bed, plenty of male flowers and almost no fruit. Aim for a modest base dressing before planting, one balanced feed about three weeks after planting, and then nothing more with much nitrogen in it.

Once fruit are set and the size of a fist, switch to a potassium rich feed every two weeks. Potassium is what actually drives sugar accumulation and flesh texture, and it is the difference between a melon that is merely large and one worth growing. Stop all feeding about two weeks before you expect the first slip, at the same time you cut the water back.

Mulch, and get every fruit off the soil

Mulch does three separate jobs for a melon and all of them matter. It evens out soil moisture, which is what prevents split fruit and blossom end rot; it stops rain splashing spores from the soil onto the lower leaves; and if it is a black plastic or woven mulch, it raises the soil temperature by several degrees, which in a cool climate can be the difference between fruit that ripen and fruit that do not.

Separately, every fruit needs to come off the wet ground once it reaches the size of a fist. A melon resting on damp soil develops a pale, soft patch on the underside that turns into rot within a week of wet weather, and slugs graze the same spot. Slide a tile, a flat stone, a piece of board or a thick pad of straw underneath. It keeps the skin dry, warms the fruit a little from below, and makes checking for the slip far easier because you are not turning the fruit over in mud.

1. Mulch before the runners spread Put the mulch down while you can still reach the whole bed. Once the vines have covered the ground you cannot lay mulch without breaking runners, and the moment for it has gone.
2. Lift each fruit at fist size Slide a tile or board under the fruit rather than lifting the fruit onto it. Twisting a young fruit at the stalk is how you lose it.
3. Do not roll fruit repeatedly Turning a melon once to place a board is fine. Turning it every visit stresses the stalk and can snap a fruit that is close to slipping.
4. Keep straw topped up Straw compacts and rots into the soil over a summer. Check it every few weeks and add more where fruit are sitting directly on the ground again.

In a wet climate, a light cloche or a sheet of clear plastic propped over the ripening fruit keeps rain off the last fortnight. This is the cheapest way to stop a good crop turning watery in a wet late summer.

Heat, shelter and the light on the leaves

Sugar in a melon is made by leaves in sunlight and there is no substitute for it. Eight hours of direct sun is the working minimum, and a plant in partial shade will make perfectly healthy foliage and fruit that reach full size and never sweeten. If your garden has a hot, sheltered, well drained corner, that is where the melons go, and no amount of feeding elsewhere makes up for it.

Wind is the underrated problem. Melon leaves are large and soft, and a young plant rocked by wind loses fine roots and stalls for a fortnight. A temporary windbreak on the exposed side for the first month is worth more than it looks, and in an open garden it often explains why one year's plants raced away and the next year's sulked.

1. Give it the hottest spot you have A south facing slope, or a bed against a wall that holds heat overnight, will ripen fruit a week ahead of an open bed in the same garden.
2. Shelter young plants from wind A cloche, a row cover tunnel or even a board on the windward side for the first month keeps the plant growing instead of recovering.
3. Do not let the canopy pile up Spread the runners so leaves lie in one layer rather than three. Only the top layer is doing any work and the layers underneath stay damp and get mildew.
4. Check for wilt at dawn, not midday Melon leaves flag in midday heat even in wet soil and it means nothing. Leaves still wilted at first light are genuinely short of water.

The weekly round, and the notes worth keeping

Melons reward a fixed routine more than they reward effort. Twice a week, walk the bed and do the same four things: turn some leaves over to look underneath, check the stem base of each plant, look at the underside of any fruit sitting on the ground, and lay out any runner that has climbed over another. On a small planting the whole round takes ten minutes and it catches almost everything that goes wrong.

Keep the notes short and tied to a place and a date. The pollination date of each fruit, the date of the first balanced feed, the date you switched to potassium, the date you cut the water back, and the date the first fruit slipped. Those five dates from one season are enough to run the next one properly, and they are far more useful than any general impression of how the summer went.

1. Turn leaves over twice a week Aphids, spider mites and downy mildew all start on the undersides. Looking only from above finds them a fortnight later than you could have.
2. Log the date you cut the water Write down when you reduced watering and how the fruit tasted. This single number does more for flavor than anything else you can adjust.
3. Record fruit positions Note which plant and which part of the bed each labeled fruit is on. When several fruit are near ripe at once you will otherwise lose track of which date belongs to which.
4. Note anything that went wrong and when First mildew spot, first split fruit, first slug damage, with dates. Next year the preventative work starts two weeks before those dates.