Marrows form part of the group of Summer Squashes from the Americas. Marrows have the ability to grow into the largest of vegetables, to win competitions at village fetes and Gardening competitions, if they are fed and watered enough.
As they have rather a bland taste and limited culinary uses, I no longer grow them. One plant is quite enough, as the fruits are so big and the plants take up a lot of space. Even the bush types need about one square metre, while the vine types will cover several metres!
Start them indoors or in Greenhouse. Use a good quality compost and sow the seed on edge in separate pots. Harden them off in a cold frame for two weeks. Plant out after all danger of frost has passed. They will benefit from plastic or cloche protection for the first month in their final positions, to protect from late frosts and cold winds.
Warning. On no account plant out these sub-tropical plants before the last expected date for frost in your area. This could be mid May for the mildest areas such as Southern coastal areas, and early June in the North of the UK. Even then, provide cloche or fleece protection for the first few weeks as cold nights and winds will cause plant damage. Gardeners are regularly caught out by late frosts occurring during the traditional cold period known as “The Ice Saints”, usually just before mid May. Remember, one night of a late frost will kill your sub-tropical plants!!
Remember that they are very vigorous plants and you should allow up to 1 sq m per plant. As the marrows form, place a tile or slate under them to keep them off the wet soil and prevent them rotting. Similarly, remove the stub of the flower once the marrow has formed, to prevent any chance of rot starting in wet weather.
If the marrows are picked while they are still small and young, they can be cooked as courgettes.
Otherwise, leave them to grow full size and cut them off the vine leaving 5 cm of stem attached to prevent bacteria spoiling the marrow. Leave to harden off in a sunny, dry, well ventilated place.
Storage. Provided that the marrows have been allowed to ripen and dry off, they will store in a cool, dry, frost free place for several weeks.
Pests and diseases. Slugs and snails can cause immense damage to the young seedlings and young plants, particularly when they are first planted out in their final positions. Make sure that you apply your chosen slug treatment immediately they are planted in their final positions.
Cucumber mosaic disease causes mottled leaves and distorted fruit, and any infected plants should be destroyed. I have never seen this disease.
Powdery Mildew can be a problem towards the end of the season, but most people do not bother about treatment.
Green Bush. This is a reasonably compact variety.