In order to grow good melons you need full sun, good drainage and moderately rich soil. Good garden soils are best, but sandy soils with plenty of organic matter added are also suitable. Clay soils, though often rich, hold too much water and therefore remain too cool for melons. Avoid acidic soils: melons do best in soils with a pH of about 6 to 7. Rather than try to modify your soil’s true nature, create raised beds—install planks around the growing area and fill in with good, organic soil. Raised beds warm up earlier in the spring, and you can use a soil mix to ensure good drainage. Or plant your melons in hills or mounds 30 centimetres high and 60 centimetres wide. Like raised beds, hills heat up faster than the surrounding soil. For all soils, add 10 centimetres of compost, well-rotted manure or seaweed every year—spread out in an area about 30 by 30 centimetres for each plant—as soon as the soil can be cultivated, and work in well.
Planting from seed
Wherever you live in Canada, start your melons indoors three weeks before the last frost date (no more): sow three seeds per 10-centimetre peat pot filled with fresh peat-based mix, at a depth of about 13 millimetres. Sowing melons in peat pots means you can plant them out, pot and all, which saves their roots from being damaged. (Note that you’ll end up with one seedling per pot; expect to get two or three melons per plant, even four in a good year.)
Cover peat pots with a plastic dome or a clear plastic bag to maintain high humidity. Place pots in a warm spot; melon seeds need 24 to 32˚C to germinate. I find placing them on top of a fluorescent lamp gets the temperature just right. If you’re growing them on a windowsill rather than under lights, use an ordinary heating pad to provide bottom heat. (You may have heard about placing seed trays on top of the refrigerator for bottom heat, but most modern fridges are too well insulated.)
Your melon seeds indoors will begin to sprout in three to seven days. Move them to a bright, sunny spot, or just beneath fluorescent lights. After germination, normal indoor temperatures (about 18 to 24˚C) are adequate, and the seedlings no longer need bottom heat. Remove the plastic covering when the first true leaves begin to show. If necessary, thin by cutting out the weakest seedlings, leaving only one per peat pot. Water seedlings when the soil mix feels almost dry, but don’t overwater. Begin to acclimatize them to outdoor conditions about a week before planting out: place in a warm, protected spot for a few hours the first day, bringing them indoors at night. Gradually increase their daily exposure to sun until they are outside from morning until evening, or overnight if temperatures remain about 15°C.
Prepping the garden
About the same time you start the seeds, begin to prepare the garden. Melon beds were once dug out and filled with fresh horse manure to generate good bottom heat throughout the spring, then covered with a layer of soil. But now that fresh manure is less readily available, most gardeners find other methods. The easiest is to use solar power: cover the planting area with plastic mulch, or use cloches or water teepees if you’re setting out plants in individual spots. Biodegradable, black plastic mulch (it converts into starch as the season advances) is widely available; there’s also a product called infrared transmitting (IRT) mulch, which lets in even more heat. Or consider using a newly available kit from a company called Exact Research, in Raymond, Alberta: the Garden Hot House includes black plastic mulch, a plastic cover and a temperature control bag. A three-week head start is usually enough to build up soil temperatures to a more-than-adequate level for melon plants.