Marrows are a firm fleshy vegetable, which belongs to the gourd section of the cucumber family, which includes courgettes, squashes, and pumpkins.There are many types and varieties, some dwarf, others almost climbers.
Marrows prefer heavier soils; they do best in positions where there is shelter from cold winds. When preparing the ground, add plenty of manure and compost where the plants are to grow; this should be dug into the ground quite deeply about 9 inches.
Begin by digging a trench 9 inches (228mm) deep put in the manure then dig another putting the soil from this into the first trench. This will form a ridge; continue to do this to add manure and compost and create a series of ridges. The marrows can be planted into the ridges, 6 ft. (180cm) apart for the trailing varieties, 4 ft. (120cm) apart for the bush types.
At the beginning of April sow the seed in seed compost in 3 in. (76mm) pots in a greenhouse at a temperature of about 50 deg. F. (10 deg C.). Harden off the young plants by putting them into frames at the end of April. Plant them out along the ridges at the end of May though it might be as late as June in the north.
Water the pots well before planting out. Avoid holding the plants by their stems as they are easily bruised causing them irreparable damage. If the weather is cool cover each plant for the first week to give them a little warmth and protection.
Trailing varieties should have the tip of the main shoot pinched back by an in. when they are 1 ½ ft. (45cm) long, this encourages the formation of side growth (laterals) on which the bulk of the female flowers will be borne.
As the plants grow they will require extra manure and compost; this should be given as mulch around the base of each plant. For extra protection against the surface roots from drying out, grass clippings can also be used as mulch.
Marrows require plenty of water so that they are able to grow and fully develop, soak the roots thoroughly and regularly. On the other hand, in very wet weather too much trailing leafy growth may result in which case; clip back the shoots to allow more air to circulate around the flowers and developing fruits.
In a good summer, marrows can often be cut in July; keep cutting them when they are young and the plants will continue cropping until well into September. If the intention is to store some for winter use, leave the fruits on the plant until October.