When you start to feel that cucumbers is no longer attractive to grow in your greenhouse, and your friends no longer visit you in late summer to avoid the free tomatoes, you should really consider of growing melons.
Sow the melon seeds in your greenhouse between mid April and end of May. Sow them directly into 3 inch pots using standard potting soil.
Once the seedlings bear two true leaves, plant them out in a cold glasshouse inside growing bags. Better yet, plant them directly into well-prepared soil (with lots of organic matter) in your greenhouse. Composted grass clippings and straws are good ideas if your melons are trenched in using the double digging method.
Create some support for your melons. This may be a single line of string tied to the supports in the glasshouse roof, which is then secured in the ground with a peg next to the base of the melons. Or, you can always use a fan trellis.
As the melons start to grow, tie the strongest shoots to the support and pinch out the side shoots that grow from the main stems. When the stems reach the top of the support, pinch out the leading shoots. This trick will help your melons concentrate on bearing more and larger fruits.
Next key is watering. Water your melons well. Oh, they love plenty of water. The best way is using a drip irrigation system. Another is inserting a 3 inch pipe when planting those melons so that water can directly touch the roots. Remember that it should be constantly moist, not wet. So water your melons well, but never too much.
Once the flowers grow, take a small paint brush and lightly brush each flower to aid pollination. It is recommended to be done during mid-day since it is when the humidity is high. After 2 or 3 days remove the male flowers (note: a female flower has a melon-like growing at its bottom part).
Once the fruits grow, feed them with a liquid melon fertilizer (the one usually used to fertilize tomatoes as well) once a week.
When the fruits are as big as tennis balls, support them using string nets. As the summer passes by and the fruits reach full size, remove a few leaves to allow them ripen. Keep in mind that in the peak of the summer your greenhouse must be kept humid by watering the path early in the morning. Keep a bucket of water standing still inside it is a good trick, too.
Growing melons may be challenging, but the rewards are worth the efforts. The harvest can be enjoyed in various dishes. Tasty sweet!