Marrows belong the the gourd section of the cucumber family. You may only need a few plants as marrows are large, spreading plants and will take up considerable space in your plot. Each plant will yield approximately four marrows.
Marrows prefer a heavy soil and a sunny, sheltered position. Select a well drained bed and incorporate plenty of manure into the plot during the previous winter.
Prepare the soil for sowing by preparing planting pockets. Space the plants 60 - 120 cm apart (depending on variety). Dig a hole 30 cm deep by 30 cm wide and fill with a mixture of well rotted manure and soil. Mound the top of the hole by 6 cm to make a ridge and sprinkle fertiliser over the surface. Sprinkle slug pellets across the surface of the soil.
You can grow marrows directly into the beds outside or you can start them off indoors to achieve an early crop.
Growing marrows outdoors
You can plant your marrow seeds directly into the bed from May onwards when the last frosts have passed. Alternatively, you can plant your marrow seeds three weeks earlier if cloches are used to protect the seedlings from frost and increase the temperature of the soil. It is advantageous to place your cloches on the ground a couple of weeks prior to planting as this will warm up the soil.
Sow three seeds spaced 4 cm apart in the centre of the pocket at a depth of 2 cm. Cover with a cloche if required. Thin out the seedlings to leave the strongest seedling when their first true leaves have appeared.
Growing marrows indoors
You can sow the seed from mid March until May. Fill 7cm pots with John Innes 'seed and potting' compost and sow two seeds per pot. Plant the seeds on their side and 2 cm deep. Place in a warm, bright position between 65-70 degrees Fahrenheit (a heated propagator is ideal). The seedlings will germinate in 5-8 days.
When the seedlings emerge remove the weaker one from each pot. You can plant out the marrow seedlings in June after hardening off in a cold frame for three weeks from the end of May when late frosts have passed. Water the pots well prior to planting and avoid holding the plants by their stems as this will damage them. You may wish to cover the plants with a cloche for a few weeks if the weather is cool.
Keep the soil moist by watering well around the plants; too much water around the base of the plant can cause the plants to trot off . You can add a mulch around the plants in the summer before the fruits have formed to aid water retention.
Keep the soil topped up with slug pellets to avoid damage by these pests. Once the fruits have started to swell feed the plants with a tomato feed every 14 days.
Marrows are ready to harvest 10-14 weeks after planting (August till October), when the fruits when they are 20-25cm long. You can check if they are ready by pushing your thumbnail into the surface near the stalk; if it goes in quite easily the marrow is suitable for picking. Cut them where they lie and lift them away.
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