Growing Melons in a greenhouse
Belonging to the same genus (Cucumis) as the cucumber, the melon requires similar conditions but provides us with one of the most refreshing fruits that can grace our table. Certain varieties of melon may be grown under cloches, in cold frames or in an unheated greenhouse, but in each case a high temperature is necessary for germination and early growth. Where this is unavailable, young plants must be purchased from a specialist grower. The owner of a heated greenhouse, however, can grow a wide range of varieties, secure earlier fruits and, if he chooses, raise plants for fruiting in frames or beneath cloches.
It is possible in the sunny zone 8 to get ripe melons in April by sowing in November but as a minimum temperature of 60°F (16°C) is required, this calls for the expenditure of much fuel in the midwinter months. Few gardeners can contemplate this and most will be content to defer sowing until the end of February or March and have melons in summer rather than spring.
Use 7cm (3in) pots and fill with John Innes potting compost or no-soil potting compost, sowing one seed in each and only just covering. A minimum temperature of 70°F (21°C) is necessary for reasonably quick germination—up to 80°F (27°C) if it can be secured—and as bottom heat is best, use, inside the greenhouse, a propagating frame with soil heating if you possess such a thing. Otherwise, try to arrange the seedpots above a hot pipe or heating tube.
Once germination has taken place the temperature may be allowed to fall to 60°F (16°C) during the night. Four weeks after sowing the roots should be hanging around the edge of the pots, and the young plants ready for transference to their fruiting quarters. These may consist of a box of soil on the staging or, in a glass-to-ground house or one with a very low supporting wall, a bed made up on the border.
Melons require rich soil and good drainage. As they are susceptible to collar rot, it is a good plan to make up the bed in the form of a ridge 45cm (18in) wide at the base and some 38cm (15in) deep. Do not plant deeply; set the plants 60cm (24in) apart.
Strings must be provided to take the melon growth up to the roof wires, as with cucumbers. Stop the shoots, by pinching out the growing points, when 16cm (6in) of growth has been made. This will result in the development of laterals: select two and train them up strings to a height of 2m (6ft) and then stop again.
The embryo melons can be seen as little swellings behind the female flowers. If one is pollinated ahead of the others, it will grow away and later fruit will fail. A good plant should give four good fruits—provided they all start level. To achieve this, remove female blossom until eight open on the same day and then pollinate these by hand about midday, transferring the pollen from the male flowers to the female with a camel’s hair brush or piece of cotton-wool.
When the little melons have started swelling, select four of the same size and remove the others. The laterals carrying the chosen fruit should be stopped one joint further on. Also stop the laterals from which any unwanted fruit have been removed.
Aim at keeping the temperature around 65-70°F (18-21°C) during the day, falling no lower than 60°F (16°C) by night. As the spring sunshine warms up, daytime temperatures may rise over 100°F (38°C) but ventilation should always be given when it reaches 80°F (27°C).
Keep the bed uniformly moist and the atmosphere damp by syringing over-head and damping down the path. The air, however, should be kept somewhat drier when the fruit begins to ripen.
Good varieties for hothouse conditions are ‘Best of All’ (green flesh), ‘Blenheim Orange’ (scarlet flesh), ‘Emerald Gem’ (green flesh), ‘King George’ (scarlet flesh) and ‘Watermelon Florida Favourite’ (pink flesh).
Where the higher temperature cannot be guaranteed, ‘Dutch Net’ (orange flesh) and ‘Hero of Lockinge’ (white flesh) may be relied upon.
Where no artificial heat is available, plants of one or more of the following varieties should be purchased : ‘Burpee’s Crenshaw’ (salmon-pink flesh), `Charentais’ (deep orange flesh), ‘Dutch Net’ (orange flesh), `No Name’ (Cantaloupe type with amber-yellow flesh), ‘Sweetie’ (Cantaloupe type, green flesh, the most likely to prosper in spite of unfavourable weather), and ‘Tiger’ (orange flesh).