All over the country, vegetable growers are harvesting giant marrows, pumpkins, carrots and other whoppers to enter into competitions at autumn shows.

Headlining the Malvern Autumn Show, Worcestershire, which this year celebrates its 20th anniversary, is The UK National Giant Vegetables Championship, which separates the men from the boys in the oversized veg world.

This area of the show smashed two vegetable Guinness World Records last year with a giant cabbage weighing in at over 130lb and a scale-breaking 1,200lb pumpkin, both by Cornishman David Thomas.

Growing giant veg is not for small-fry gardeners. Producing a prize specimen takes a huge amount of work and a lot of plant-based mollycoddling.

You need to beef up your soil with organic matter, fine-tune individual techniques and spend three months of the year preparing your land for giant things to come and the other nine coaxing seeds into big guns.

Choosing the right seed is all-important, because some varieties grow much larger than others. 'Atlantic Giant', for instance, is the biggest variety of pumpkin and current holder of the world record, but it's not one for eating. Exhibition leeks, known as giant pot leeks, are short and squat and grown for their weight but are only available from specialist suppliers.

Seed catalogues and specialists offer giants like Old Colossus Heirloom Tomatoes, Oxheart carrots, Kelsae sweet giant onion and Carolina Cross watermelons. Northern Giant Cabbage (weighing up to 100lbs), the Japanese Imperial Long Carrot (more than 12in long) and the Mammoth Zeppelin cucumber, weighing in at 16lbs, are also contenders.

Many growers save the seeds from their largest fruits to plant next year. Most prize-winning large vegetables are open-pollinated so seeds can be saved.

Seed companies such as Medwyn Williams (www.medwynsofanglesey.co.uk) and W Robinson and Son (www.mammothonion.co.uk) specialise in giant veg and provide growing information on their websites.

Starting vegetables off early in artificial heat to give them a long growing season and harvesting late are two of the main necessities for success.

Vegetables such as pumpkins are easier to grow because they aren't started off until April, but leeks and onions need to be started off under glass in November and will need tending all through the winter if they are to become giants.

Trusses of runner beans and tomatoes need to be thinned to a point where you might just have one specimen left on the plant and all the energy goes into that one fruit. Tomatoes are heavier when they are green, hence almost all heavy tomatoes you'll see on a show bench are unripe.

Add slow-release organic fertiliser at planting time to ensure the nutrients are there when they are needed, as giant veg tend to grow in quick spurts. Use the appropriate feed, so if you are growing the plant for the fruit you'll need plant food high in potassium and phosphorous, but if you are growing leafy veg like cabbage you'll need a fertiliser with plenty of nitrogen.

Anyone growing giant veg will know that sporadic watering could spell disaster. Water your veg thoroughly on a regular basis or the fruits may split, so it's probably wise to sort out drip irrigation if you are serious about winning that competition.

So, what sort of size might you be aiming for? The world's largest marrow weighed in at over 14st - equivalent to the weight of sporting Rugby legend Jonny Wilkinson.

Malvern Autumn Show regular Peter Glazebrook is famed for growing a colossal cauliflower weighing in at 60lb, measuring 6ft wide. That's 20 times heavier than your average supermarket staple!

The world's longest carrot measured in at 5.83 metres - that's the equivalent to the length of one and a half Mini Coopers.

Some growers claim their giant veg are tasty, but I'm not so sure. Giant root vegetables are surely too woody for the palate and any giant marrow would have a tough, leathery skin which no amount of cooking would soften.

Better just to enjoy the visual splendour of these prize-winning giants.

:: Malvern Autumn Show takes place on Saturday, September 26 and Sunday, September 27 at the Three Counties Showground, Malvern, Worcester. For information on ticket prices, visit www.malvernautumnshow.co.uk or call 01684 230128.

BEST OF THE BUNCH - Chrysanthemums

These cheery perennials bridge the gap between late summer and late autumn and although in recent years they've gone out of fashion a bit, new varieties are springing up to give them a boost. C. 'Burnt Orange', for example, with its spoon-shaped petals in shades of deep orange through to yellow, was recommended in a Which? trial, while C. 'Mary Stoker' bears blooms which change from apricot to soft pink as the flowers mature and they also provide good cut flowers. Chrysanthemums look great in pots or at the front of borders. They prefer rich soil that retains moisture and need to be planted in a spot in full sun to flower well.

GOOD ENOUGH TO EAT - Kohl rabi

Once a rarity, this member of the cabbage family is now commonly found in supermarkets. The stem base is the edible swollen part. It is not a root, so can be grown in shallow soils. Sow the crop thinly in drills 1cm deep, 30cm apart, in late spring through to summer in a sunny spot and sandy soil which has been dug in autumn. Compost should be added if the soil is short of humus. Thin the seedlings when the true leaves appear, and continue thinning until the plants are 15cm apart, providing protection against birds and weeding regularly. Soak the ground during prolonged dry spells. Pull the swollen stem bases when they are a little bigger than a golf ball. They can be grated into winter salads or stir-fried, boiled or mashed with root vegetables. Good varieties include 'Azur Star' and 'White Vienna'.

WHAT TO DO THIS WEEK

Bring in house plants which have been standing outdoors for the summer before the evenings become cold and the first frosts beckon.

Continue to plant spring-flowering bulbs including daffodils and hyacinths.

Tidy up climbers, removing any rubbish that has built up at the bases of the plants during summer.

Clematis cuttings propagated under glass in the spring should now be established and can be planted out in their growing positions.

Pot arum lilies for winter-flowering under glass, using John Innes No. 3 potting compost.

Cut gladiolus flower spikes regularly, leaving at least four leaves on each plant.

Give mid and late-flowering greenhouse chrysanthemums a feed of balanced fertiliser until the buds show colour.

Pick autumn-fruiting raspberries, but cover the bushes with horticultural fleece once the weather turns cold at night, to prolong fruiting and protect the berries.

Plant spring-flowering annuals and biennials now, especially in cold areas, to give them as much time as possible to establish themselves before winter.

Clear out the pond.

Continue to remove weeds so that they don't shed seeds which will remain in the soil over the winter.

Lift tender or slightly tender perennials such as argyranthemums, fuchsias and pelargoniums to be overwintered under protection.

Strip most of the leaves from tomatoes and peppers to encourage ripening of any remaining fruits.