Marrows are easy to grow from seed and can be sown outdoors in the spot where they are to grow, or you can start them off indoors in pots.
Sow two or three seeds 2.5cm (1in) deep outdoors in late May or early June and cover with cloches, jars or plastic; leave in place for two weeks, or as long as possible, after germination. Thin the seedlings to leave the strongest one.
For earlier crops or in cold regions sow seeds indoors on their side 13mm (0.5in) deep in 7.5cm (3in) pots of compost from mid- to late April at 18-21C (65-70F).
If you don’t have the space to raise marrow seedlings, you can also buy young plants from garden centres in spring and these usually can be planted outdoors straight away (check with the shop when you buy them).
Two weeks before planting or sowing seed outdoors, make planting pockets 1.2m (4ft) apart for marrows. Do this by making a hole about a spade’s depth, width and height and fill with a mixture of compost or well-rotted manure and soil. Sprinkle a general fertiliser over the soil. Plant one plant on top of each planting pocket.
For indoor-raised seedlings, plant outside on top of your planting pocket in early June, hardening off (acclimatising) before doing so. Do this by moving them into a coldframe for a week or, if you don’t have a coldframe, move plants outdoors during the day, then bring in at night for a week; then the following week, leave them out in a sheltered spot all day and night.
You can also grow marrows in growbags or containers (at least 45cm/18in wide). Plant one or two per growbag, or one per container.
Keep the soil constantly moist by watering around the plants not over them. As they need plenty of water, sink a 15cm (6in) pot alongside the plants when planting out. Water into this and it will help ensure that the water goes right down to the roots and does not sit around the neck of the plant, which can lead to rotting.
Feed every 10-14 days with a high potash liquid fertiliser once the first fruits start to swell.
The fruit of marrows should be supported off the soil on a piece of tile or glass.
Powdery Mildew: Appears as a white powdery deposit over the leaf surface and leaves become stunted and shrivel.
Remedy: Keep the soil moist and grow in cooler locations.
More info on Powdery Mildew
No fruit, or fruit rotting when very small: This is a physiological problem, caused by the growing conditions, not a pest or disease. It is a problem when the weather in early summer is cool and this causes inadequate pollination.
Remedy: This is usually a temporary problem and once the weather starts to improve, so will pollination. You can try to hand-pollinate plants yourself by removing a male flower (no swelling at their base) and brushing the central parts against the centre of a female flower (female flowers have a swelling at the base – this is the beginning of the fruit). But this is a bit of a hassle, and normally the plant will correct this problem itself.
More info on No fruit, or fruit rotting when very small
Grey mould: A usually grey, fuzzy fungal growth which can begin as pale or discoloured patches. Grey mould ( botrytis) is a common disease especially in damp or humid conditions. Spores enter plants via damaged tissue, wounds or open flowers. Mould can also damage ripening fruit such as strawberries. Black resting spores survive over winter.
Remedy: Remove damaged plant parts before they can become infected. Cut out infected areas into healthy tissue and clear up infected debris. In greenhouses, reduce humidity by ventilating and avoid overcrowding of young plants and seedlings.
More info on Grey mould
Harvest marrows as needed. If growing for show, take off all developing fruit and leave just one on the plant, so that the plant will put all its energy into ripening just one marrow.
‘Badger Cross’ AGM:F1 hybrid. Later bush variety of small, good shape with dark striped fruits. Claimed Cucumber Mosaic Virus tolerance.
‘Clarita’ AGM:An early cropping F1 hybrid. Offers high yield of pear-shaped, green-white fruits. It needs cutting when small.
‘Minipak’ AGM:A later bush variety with small dark striped fruits.
‘Tiger Cross’ AGM:This is a striped marrow variety, producing high yields of large striped fruits, good for winter storage. Claimed to be Cucumber Mosiac Virus tolerant.