Marrow: growing marrows & uses

Often a hot topic of horticultural shows and village fetes, marrows can also be used in the kitchen. Discover how to grow marrows and how best to eat them.

The marrow is a staple of allotments and vegetable patches nationwide and can grow to an extraordinary size. So much so that regional competitions are held during the summer to find the biggest. Nonetheless, marrows are also a versatile fruit and a key ingredient in many Asian and European recipes.

Marrow vs. courgette

You may well be wondering what the difference between a marrow and a courgette is. Put simply, a marrow is just a giant courgette (Cucurbita pepo), or zucchini as they are also known, that has been allowed to mature. Belonging to the Cucurbitaceae family, courgettes are a variety of summer squash (Cucurbita) and originate from Italy where they were initially bred in the 1800s.

Recognisable by their large, green, lobed leaves and orange-yellow flowers, the stems and foliage are also often covered in tiny hairs. There are many courgettes varieties available with green, yellow, or even stripey fruits and a variety of growth habits, such as bush types that grow to around 1m or climbing courgettes that can grow up to 2m high. Either way, generally, the fruit is classed as a courgette when harvested young, with fruit no longer than 8 to 12cm, and as a marrow when the fruit is longer than that. It is worth noting that courgettes and marrows also differ in taste. Courgettes tend to be sweeter than marrows and do not develop their milder flavour and tough skin until they mature.

Growing marrows

To encourage your marrows to mature to a good size, you need to give them plenty of space and grow them on a rich and fertile soil in full sun. You can either choose specific marrow seeds or less prolific courgette varieties, which will mature into marrows.

Growing marrows is similar to growing courgettes and you can sow seed under cover in April or directly in the ground in May or June. When sowing under cover, prefill a small pot or module tray with a seed sowing compost and sow the seeds on their side at a depth of 1 to 2cm deep. For this you could use our Plantura Organic Herb & Seedling Compost, as it is low in nutrients to encourage the seedling’s roots to grow. Once sown, place the pot in a propagator at a temperature of 18 to 21 °C and keep the soil moist.

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Once the first true leaves appear, pot on the small marrow plants using a general-purpose compost. Our Plantura Organic Tomato & Vegetable Compost can be used for potting on marrows, as it is enriched with essential nutrients to support their growth and being peat-free, it is good for the environment.

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Once the marrow plants have developed a good root system, you can gradually harden them off before planting them outside once all risk of frost has passed. A spacing of 1m between plants is advisable to give the marrows room to grow. To prepare the planting site, incorporate some well-rotted manure and apply a granular fertiliser to enrich the soil. For this use a granular tomato fertiliser that consists of nitrogen, phosphorus and potassium. For example, our Plantura Tomato Food contains the necessary nitrogen, phosphorus and potassium to support healthy growth and flower and fruit production and will feed the plants for 2 to 3 months. You can also grow marrow plants in a large container or planter, just like growing courgettes in pots, but due to their high moisture and nutrient requirements, they tend to grow better in the ground or a raised bed.

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Even more so than courgettes, marrows require the soil to be kept moist and regular watering is needed to encourage the fruits to swell. You can also mulch marrow plants, which will not only help prevent moisture loss but keep the weeds at bay as well. If you are aiming to grow fewer but larger marrows, remove all but 2 to 3 fruits to ensure the plant’s energy is not overly divided.

Once the courgette flowers begin to form, fertilise the plants every 10 to 14 days with a liquid feed, such as our Plantura Liquid Tomato Food. Being larger than courgettes, marrows take longer to grow and can be left on the plant until they have reached the desired size. However, the larger marrows get, the more bland and watery the flesh becomes.

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How to use marrows

When it comes to picking marrows, the method is the same as when harvesting courgettes. With their thick skins, you can store and preserve marrows for several months in a cool but frost-free space. Along with winning competitions, there are many uses for marrows. Common marrow recipes include grating, roasting, stuffing and even making soup. You can also collect the marrow seeds to sow again the following spring. To harvest the marrow’s seeds, remove the seeds from the pulp and allow them to dry thoroughly before storing them in a paper envelope in a dark, dry and cool place until sowing time.

Are marrows poisonous?

Due to the presence of toxic cucurbitacin compounds, courgettes and marrows can sometimes taste very bitter. Often caused by plant stress or cross-pollination, if you discover that you have bitter courgettes or marrows you should discard them and not eat them.