How to Grow a Giant Marrow
How did we grow Britain's Largest Marrow?
In October 2009 we prepared the marrow patch on an area measuring 7m x 4m (23ft x 13ft). It was a well drained and sheltered area of the garden and the ground was double-dug to create depth and allow well-rotted manure to be dug in early enough for the worms and bacteria to carry out their magic during the winter months.
To grow a giant marrow you will need the right seed an ordinary strain will never achieve the required size. Ours were started off at the beginning of May 2010 in a heated greenhouse. Due to the freshness of the seeds they germinated with ease; however, as a precaution, we used sandpaper on the edges of the seeds to help them germinate. The marrows were planted in pure vermiculite and took around 7 to 10 days to germinate at a temperature of 21°C (70°F).
In early May we prepared the soil using a rotovator, which made light work of an otherwise strenuous task. Then, a week before planting, the bed was prepared with a base fertiliser of Vitax Q4 at approximately 170 to 225g (6 to 8oz) per square metre.
Towards the end of May and the beginning of June, when all danger of frost had passed, the marrows were planted into the patch. A new method was trialled and we added 10g (1/3oz) of Rootgrow around the plant. This mycorrhizal fungus helped to create a huge root mass, and we believe this was one of the key ingredients of our success.
Due to the size of our patch we could only grow two marrows, and as a precaution we positioned a mini-tunnel over the plants to give them a head start. This kept them out of the wind, and also kept them warm during thecooler nights. On strong sunny days the tunnel was covered with a sack to prevent the leaves from scorching and the roots from cooking. The mini-tunnel was removed in mid June.
The plants were allowed to grow to about 4.5m (15ft) long, with the fruit being set on the main vine at about 3 to 3.5m (10â to 12ft). The side vines were stopped at about 1 to 1.5m (3 to 5ft) and the main vine and side vines were buried to help stabilise the plant and promote growth, as marrows root along all leaf joints.
Throughout the growing season we supplemented this with a fortnightly scattering of poultry pellets and a weekly foliar feed with Maxicrop Triple, a seaweed-based product. We also regularly sprayed the leaves with a 10:1 mixture of whole milk to control powdery mildew if not controlled this will kill the plant.
We've been developing our strain over the past twenty-five years, and for consistency we ensured that the male and female flowers were covered the evening before they started to open. In our experience pollination is best carried out early to mid morning. Our marrow was pollinated forty-five days before the Malvern Autumn Show and the female flower was covered with a plastic bag secured with a rubber band for two days after pollination. It reached 77.5kg (171lb) in approximately seven weeks, and we avoided growing table marrows and courgettes, as there was always a risk of cross-pollination.
We rested the developing marrow on top of a polystyrene board, believing that this would help to avoid differences in temperature and prevent the marrow from having excessive growth spurts, which would have caused it to split. You may also have heard a rumour that our marrow was wrapped in a duvet towards the latter part of the growing season. Well, it's true. Once the skin becomes hard, a marrow has stopped growing, and this prevented the skin from getting hard, allowing the marrow to continue its growth. All we needed now was good weather and lots of luck.