5 Secrets to Growing Amazing Tomatoes (That Actually Work)

6 May 2023, written by Benedict Vanheems

Nothing says summer like tomatoes, and with warmer days upon us it’s time to get them planted! Read on our watch our video to discover the best planting tips, which supports to use for different types of tomato, and how you can boost your harvest…with fish heads. No, really!

Harden Off Before Planting Tomatoes Outdoors

Before planting it’s important to acclimatize tomato seedlings to the great outdoors over a period of about a week. This process, known as ‘hardening off’, ensures they aren’t shocked by too much sun, wind and cooler temperatures all at once. Once temperatures are reliably well above freezing in your garden, pop your tomato seedlings outside somewhere sheltered for a few hours each day. Leave them out for increasingly longer periods as planting time approaches. A cold frame makes a superb halfway house and you can prop open the lid increasingly wide as the days roll on.

If you don’t have the time, space or inclination to grow plants from seed, most plant nurseries and garden centers offer a solid selection. Inspect plants before buying if possible – they should look strong, sturdy and, crucially, green, free of any discoloration. They will often need to be hardened off in the same way before planting.

“Tomatoes-in-sun” — Tomatoes love plenty of warmth and sunshine

Planting Tomatoes Successfully

Tomato plants love sunshine and warmth, and this is precisely what will help the fruits develop their fullest flavor and aroma. There’s nothing quite like cupping a just-picked tomato, still warm from the sun’s rays, and breathing in that irresistible scent. Pure ambrosia!

So be sure to pick the sunniest spot in your garden – one that gets at least six hours of direct sunshine a day – and preferably more than that: eight, ten, all day…the sunnier the better!

Like many vegetables, tomatoes prefer a goldilocks soil that is moisture retentive yet well drained and, of course, rich in nutrients. The very best way to achieve that is simply to add plenty of well-rotted organic matter to the surface of your soil in the weeks or months before planting. Adding it well in advance of planting will give worms and other soil organisms time to break it down a bit so it’s in good condition with plenty of available nutrients when your tomatoes are planted.

To get the best from your plants, they need plenty of light and space. They’ll need at least 18in (45cm) between plants and a minimum of two feet (60cm) between rows. Proper spacing not only means more light can reach the plants, it also improves airflow around them, which is a major step towards avoiding any disease problems.

“Watering-tomatoes” — Plant tomatoes deeply to encourage them to produce roots up their stems

Persuade Tomatoes to Grow More Roots

Tomatoes are incredible plants because they can produce roots at any point along their stem. With this in mind, we can plant them a bit deeper than most plants so that more roots are produced at the base of the stem. This helps anchor the plants into position, creating a really strong foundation for success, and more roots will help plants to draw on more moisture and more nutrients. Dig planting holes that are quite a bit deeper than the depth of the rootball so you can bury some of the stem.

If you’re planting into a growbag you can encourage these extra roots by planting your tomatoes into the top of the bag as usual, and then popping a bottomless pot over the top. Fill that part way with extra potting mix to bury the stem so they can root into that. It also means that when you water into it, the water is held in a reservoir at the top rather than pouring off, and can drain directly down to the roots below to avoid wastage.

Fish Fertilizer For Tomatoes

I’d heard of fish heads being used in the base of planting holes and, if I’m totally honest, have rather scoffed at the idea in the past. But on doing a little more research it turns it this isn’t such a bad idea after all. Fish is loaded with nutrients which, as it breaks down into the soil, the tomato’s roots can tap into. Native Americans have been doing this for thousands of years, planting the ‘three sisters’ of corn, squash and beans over fish with great results. And we’re often advised to water on fish emulsion or use fish-based fertilizer, so it makes sense, right?

Hold your nose and put a couple of fish heads into each planting hole, then cover with a layer of the dug-out soil. This both serves as a buffer between the roots and fresh fish until it has started breaking down a bit, and should hopefully help to mask the smell from wandering wildlife and pet cats and dogs!

Plant your tomato on top, then it’s simply a matter of back-filling with the soil, burying the bottom few inches of stem up for good measure. Remove the seedling leaves and perhaps the first pair of true leaves to enable deeper planting. If you’d prefer not to use animal products, comfrey leaves make a great vegan alternative.

To finish, water on a weak liquid seaweed solution to give your plants a bit of a lift and help settle them in. Once the plants start flowering, give them an occasional liquid feed of either tomato fertilizer or a home-made liquid feed.

Supporting Tomatoes

Most tomatoes appreciate some form of support to keep them up off the ground so that fruits don’t rot or get eaten by the likes of slugs. How you support tomatoes depends on what type you have:

Determinate (or bush) tomatoes get their name because they have a determined height they’ll get to, and they won’t grow any taller – unlike those ever-skyward indeterminate tomatoes! The simplest way to support these determinate tomatoes is with bamboo canes or stakes, which should be sufficient for even the heaviest plants laden with weighty fruits.

Indeterminate tomatoes, also known as cordon or vining tomatoes, easily reach head height or even more, so for those you’ll need sturdy stakes. Push them down into the soil so they stand nice and firm, then tie the stems in as they grow. Do be careful not to drive them right through the roots of your young plants though, or perhaps get the supports in position before planting.

To encourage efficient flower and fruit production, pinch out sideshoots coming from the main stem, which will also help to keep plants from wasting too much energy on excess foliage. This pruning is only necessary for indeterminate tomatoes, and if you’re in a hot climate you may find that tomatoes grow so vigorously that you can get away without pruning. But in my chillier climate, removing those sideshoots is a must!

How to Make Tomato Cages

Tomato cages are a great alternative for supporting determinate tomatoes, particularly vigorous varieties that produce lots and lots of branches. Unlike vining types, determinate tomatoes don’t need any pruning and tend to crop over a much shorter period, which makes cages very suitable. But purpose-sold tomato cages don’t come cheap! So, its common sense to make your own.

The easiest way to do this is to use a sheet of concrete reinforcing mesh, or remesh. Alternatively, use cattle fencing. It comes on a roll, which means it’s easily cut to suit the width of cage you’d like. A diameter or about 18in (45cm) is good, though you might want to go a bit wider than this for the most vigorous varieties. To fix the ends together you could use zip ties or even strong string, or just fold the cut ends of the wire around the vertical strands of wire on the other end. Sometimes you need to flex or roll the wire cage to create more a perfectly round shape.

Tie the young plants to stout lengths of bamboo canes to support them while they’re still small. The cage will come into its own as the plants bulk out. Finally, anchor each cage to the ground by pushing in bamboo canes at opposite sides. Either weaving the canes through the horizontal wires, or tie the cage to them.

“Dill” — Grow dill near your tomatoes to improve pollination

Companion Plants For Tomatoes

Your tomatoes are planted, you’ve watered them in, and you could just leave it at that. But what better way to finish off your totally terrific toms than with a support act of companion flowers!

Marigolds make excellent companions for tomatoes. Not only will they add a flash of color as they carpet the ground beneath your tomatoes, they’ll also help to deter whitefly. Dot them here and there at the foot of the tomato plants and, in a few weeks’ time when they come into flower, they’ll really tempt in the pollinating insects.

Another great companion for tomatoes is dill. If you’ve ever seen dill in flower you’ll know how much beneficial bugs like hoverflies absolutely love it! If you’re wondering what makes a good companion to any vegetable, check out our Garden Planner, which includes a Companion Planting feature that shows ideal bedfellows for any selected crop.

And finally, basil - because basil and tomatoes are the perfect pairing after all! Plant them next to your tomatoes so you can pick some leaves when you pick your tomatoes.