How to Plant Tomato Seedlings

Bare root winter fruit varieties

Homegrown cherry tomato in the UKHow to successfully grow tomato plants in the UK. I had a call from Dermot Carey (my personal vegetable guru) over the weekend as he wanted to pick up a couple of rolls of fleece. “I hope you don’t mind me calling on a Sunday morning” says Dermot “No problem” says I, “you might stick the head in and have a look at my tomatoes while you’re here”.

‘Having a look’ at my tomatoes meant having a look at some tomato seedling plants in their pots, an empty bed, some twine and all the tools Dermot would require to plant them. I also thought he might like to ‘have a look’ at some cucumbers and French beans while he was at it.

Anyway, as you can imagine, it all turned out rather well (for me) and we (he) got everything perfectly planted and set up for a fabulous harvest. Now, might you be thinking I was being a bit selfish and, God forbid, lazy by getting Dermot to do most of the work? On the contrary, it was you I was thinking of. Didn’t I get a load of great photos and took reams of notes so I could produce a top class article on planting tomatoes? All for you? Aren’t I great?

Joking apart, with huge thanks to the infinite fountain of vegetable growing knowledge that is Dermot Carey.  Dermot runs his own vegetable growing courses from time to time, and places are widely sought after.

A healthy tomato seedling in a raised bedPick good plants
It sounds obvious but choose nice stocky seedlings rather than long, leggy examples. It’s always better to start with the very best seedling you can as coaxing a weak plant to health is time consuming and rarely leads to a good result. We’re not running a plant hospital here – this is the Olympics.

If you’re too late to sow tomato seeds (which you are if you’re reading this on the date I posted it) then you need to buy your plants from a good seedling supplier. Though I’m generous to a fault there are no spot prizes this time for guessing who I’m going to recommend……

We (Quickcrop) have a delicious cherry, our favourite ‘Sungold’ and a juicy and high yielding full size variety ‘Shirley’. Both are available with other warm climate crops like cucumber, peppers and courgette in our 6 cell choose your own plant trays. Choose as many as you like of each variety as long as it adds up to 6.

6 Cell choose your own plant tray.

Preparing a raised bed for sowing tomatoesPreparing the soil
A good tomato plant going full tilt can produce hundreds of delicious fruits but that won’t happen unless the plant has enough food. Tomatoes need a lot of nutrients to build long vines and to produce heavy trusses of fruit. Good preparation is crucial.

The best feed is a good composted farmyard manure and/or a good quality garden compost. If you haven’t previously fed your soil you should dig these into the bed or if you prefer to use the ‘no dig’ method you can spread them as a mulch on the surface. The mulch will take a little longer to work down to the roots from the action of the worms so is more effective added at least a month before planting.

I like to use the products we sell to make sure they work and to keep an eye on quality so here’s what I used to prepare my beds:

Envirogrind soil improver (garden compost) – 1 x 60 litre bag per 6ft by 3 ft bed.
Lady Muck composted horse manure – 1/2 bag per 6ft by 3ft bed.
Seamungus seaweed and poultry manure pellets – A small handful around each planting hole.

Of course you may have your own supply of manure and compost which is perfect, just make sure the manure is properly composted (no smell). I think I would always suggest investing in the Seamungus as it’s such a handy feed for all sorts of applications but especially when planting out heavy feeders like tomatoes, squash or courgettes.

Hanging twine to tie up tomato seedlingsString ’em up!
Tomatoes are vine plants and would be perfectly happy producing masses of foliage, a small amount of fruit and covering the ground in your polytunnel. Unless you are growing bush varieties we need to bend vine or ‘cordon’ tomatoes to our wicked ways to get them to produce the harvest we want.

You will need to create a support for your vines to grow up which in our case will be lengths of twine. You can use canes but if you have something to tie a length of twine to it works a lot better. I have crop bars in my tunnel so we attached a light rope between the bars to create a support to hang our twine from. You can see Dermot tying on our support strings to the rope running the length of the tunnel.

Cutting the string at base of tomato seedlingDermot uses a slip knot as the twine will need to be loosened as the the stems thicken up and as the tomato plant increases in bulk. You may also need to tighten the string if the vine sags and you need to straighten it up. We recommend using a synthetic twine as natural fibre can rot and break in the humid atmosphere of the greenhouse or tunnel.

Tie your strings approx 15 to 18 inches apart as obviously this will determine how far apart you plant you tomatoes. Leave another 12 inches spare after the twine has reached the ground as this will be buried underneath the root ball to anchor the vine to the soil.

Tomato seedling plant stemPlanting your tomato seedling plants
You can plant your tomatoes up as far as the base of the first set of leaves as the hairy part of the lower stem will produce roots and will give a stronger and more extensive root system. This is handy if your plants have become a bit leggy as you bury much of the elongated stem. You can plant even deeper if you have particularly leggy plants

Remove the first seed leaves and side shoots which you can see just above Dermot’s finger and thumb in the photo. You will see the seed leaves are a long uniform shape unlike the more complex shapes of the leaves above. The side shoots are the leaves immediately above the seed leaves.

Location of seedling tomato side shootYou also need to pinch out the rest of the side shoots moving up the stem. The side shoots are the little leafy shoots directly above the leaves, they grow out of the join between the leaves and the main stem. You might as well get to know these now because you’ll be pinching them out every week as the tomato vine grows.

As I mentioned already, what the tomato wants to do and what you want it to do are very different things. If you leave these side shoots the plant will grow off all over your greenhouse and produce very little fruit in the process. Nip these little shoots out between finger and thumb when they’re small, they break off easily by bending them forward and back.

Dig a hole slightly larger than pot your plant is growing in. The spacing is approx 15 -18 inches between plants and 26 – 30 inches between rows.

I like to mix in a bit of Seamungus at this stage as over the years I have noticed a marked difference in the growth of the plants. Sprinkle a small handful in the planting hole but also more broadly around the area. Remember tomato roots may be small in the plant pot but they will spread to form a broad root system which all needs access to nutrients.

Planting tomato seedling plant with string supportPlace the end of your twine in the hole and plant your tomato on top of the string. The roots will grow around the string and anchor the support firmly to the bed as it grows.

Firm the soil or compost in around the seedling from the sides to remove any air pockets around the plant. Firming seedlings in is more about pushing the soil in around the roots rather than applying pressure from above. If you push down on the soil, especially if you have a heavy clay, you may form a hard crust which prevents water easily reaching the new seedling.


Using twine to support a tomato plantCoil the twine gently around the stem taking care not to damage the leaves. You will need to continue to do this as the plant grows which is an easy and strangely satisfying thing to do. Simply wind the main stem around the twine every week or so when you’re pinching out the side shoots. You are better off doing this when the main stem is 4 or 5 inches long as the tender tip can easily be broken off by mistake.

Make sure to keep your plants watered throughout but especially when the tomato plant is becoming accustomed to its new home. The soil should be moist but not soaking with watering advised in the early morning rather than at night time. We’ll be coming back to these plants later in the season to show off our progress and hopefully provide you with more useful information.


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