Growing tomatoes at home can be extremely rewarding. There are few things better than getting to eat a delicious fresh tomato grown in your own back garden.

But there are pitfalls. And one of the most frustrating is creepy crawlies munching on your carefully-cultivated plants before they've had a chance to bear fruit. Tomato plants are vulnerable to aphids, spider mites and whiteflies, which can seriously damage your plants if left to run riot. 

Whiteflies and aphids are particularly troublesome, draining sap from leaves and stems, leading them to yellow and curling. While using store-bought sprays to deter them is an option, lots of gardeners don't like to use artificial chemicals on their plants.

That's where gardening legend Alan Titchmarsh comes in, revealing his personal tip for keeping pests off your precious crops. Alan says planting another plant next to your tomatoes – known as companion planting – can be just the ticket for keeping the bugs away.

While some plants attract pollinators such as bees, others can be used to deter pests. One of Alan's favourite pairings is tomatoes and French marigolds.

Speaking on his YouTube channel Gardening With Alan Titchmarsh, the Yorkshireman said French marigolds are "very good for attracting pollinators who come for its nectar and its pollen... but it's also particularly good when planted with one other crop, and that crop is the tomato".

The surprise advantage of French marigolds lies in their roots – they emit a scent that pests find offensive, which is remarkably beneficial to tomatoes when shared in the same soil. The easiest way to grow them together is simply to pop the marigolds in the same grow bag or plot as the tomatoes.

Alan said: "You will find that the fact that the root exudate is so strong it puts off the whitefly. So what's going to happen now is that those aromatic roots are going to mingle with the aromatic roots of the tomato, and in some way they do seem to deter whitefly."