How to Grow Tomatoes
First of all, check the product page to make sure you know whether you're growing either a vine or bush variety as they will need slightly different care. We've detailed specific tomato plant care instructions for you in the FAQ section below.
How to grow tomatoes
When to plant tomatoes
Tomatoes should be planted outside from May-June.
Keep the plant indoors and grow in a sunny spot such as a window sill from April.
How much sunlight do tomatoes need?
Tomatoes need to be planted in full sun.
This should be somewhere where they will receive 6-8 hours of sunlight every day.
Where should I position my tomato plants?
Tomato plants should be positioned somewhere they will be sheltered from cold winds.
By a wall or even in a greenhouse or conservatory would be best.
How to water tomato plants
In spring, you should water your tomato plants at least twice a week.
When the weather gets hotter, and particularly when we get those scorching days, this may need to increase to as much as once a day.
You should aim to keep the soil consistently moist at all times. If the moisture level in the soil fluctuates too wildly, then this could cause the fruit to split.
Tomato plants are notoriously thirsty and hungry – they need the resources to produce big loads of delicious, juicy tomatoes.
An easy way to check if the soil is too dry is to simply feel it. Put your finger about an inch into the soil, and if it is dry then give it a watering. This might require a close eye at first, but you’ll soon know how much water they need based on how hot it is–like some kind of tomato whisperer…
We also recommend that you add a mulch such as fine wood clippings or straw to the top of your soil. This will help the soil retain moisture, heat, and also prevent disease.
How to feed tomato plants
When you start to see flowers emerge, tomato plants need a serving of high potash feed every week such as organic liquid tomato feed.
When you first pot your plant, you can give it one serving of a balanced (meaning it has an equal amount of nitrogen, phosphorus and potassium) plant feed. This helps the green parts of the plant to grow.
When you start to see flowers emerge, you will then want to switch to a serving of high potash feed every week. Potash (or potassium) promotes flower and fruit growth and the tomato plant will want a lot of this. High potash feeds are very common and can come as a liquid feed.
How to stake tomato plants
Determinate (bush) and indeterminate (vine) require different amounts of support.
Bush varieties can cope with a smaller stake placed into the ground about 5cm from the base of the stem. Simply tie the stem to the stake every 15-20cm with some string leaving a gap that allows the stem to grow.
Vine varieties will need larger, more sturdier stakes as the plant can grow taller than 2m. Again, tie the stem to the stake every 15-20cm, leaving room for the stem to grow. You can also train vine varieties up vertical string by wrapping the stem around it as it grows or a trellis.
For the bush varieties, you can use a smaller stake, such as a bamboo stick. They won’t need too much support as their growth is determined at a height that the plant can better support.
As mentioned, the vine varieties will need studier and/or taller support as they can grow in excess of 2m. One structure growers sometimes use to grow vine tomatoes is string hanging down from a support structure such as an A-frame. This string has to be tied around a hook and then planted into the ground at the base of the plant to keep it in place.
Simply wrap the stem around the string or trellis vertically training its growth upwards. You will want to monitor and train the stem every couple of days because in summer tomatoes grow rapidly and you don’t want the stem becoming too thick as you wrap it around the support as this could cause damage.
How to prune tomato plants
For both bush and vine varieties of tomato plant, prune off all the leaves that are within 10-15cm of the soil.
For bush varieties, this is basically all you need to do.
For vine varieties, you also need to remove the ‘suckers’, the shoots that grow the corner, or armpit, of the main stem and the side stems. Simply pinch or cut these suckers off. The goal is to train one main stem up vertically from which all your fruit will grow.
The reason why we do not prune bush varieties as much is because their growth is determined at a set size and that’s as big as they will grow. So we are looking to get as much fruit out of them as possible from all the stems they produce in the shorter period of time they will grow and crop.
For indeterminate varieties, they will grow and crop continuously for as long as they can, so it is more beneficial to try and specifically train their growth through pruning.
How to pot tomato plants
- Plant plugs into a 9cm-ish diameter pot with a mix of 3 parts compost and 1 topsoil.
- Fill your pot with soil, make a little hole just big enough for the roots to fit in, put your plant in the hold and backfill with soil, gently firming in with your fingers.
- Give the plant a watering to settle the water around the roots.
- Grow on for approx 3 weeks, protecting from any frost by keeping them inside in a sunny spot such as a window sill. Once approx 20cm tall, and the chance of frost gone, your tomato is ready to be potted on (see below).
Grow your tomatoes in a pot
It allows you to move them around and indoors if the temperature or amount of sunlight demands. Tomato plants hate the cold and need sunlight to produce ripe fruit.
Here's a top tip for potting on...
When potting on your plant, build a trifle. The area just above the base of the stem of a tomato plant can produce extra lateral roots. The more we can promote this growth, the stronger and healthier our plant will be.
When you move your plant to a 30cm pot, gently squeeze the plant out of its 9cm pot, place the plant and root ball at the bottom of the pot and fill the sides with soil until it’s level with the root ball.
Wait 3 weeks and add a couple more inches of compost, covering the base of the stem. Repeat every 3 weeks, like your making the world's slowest trifle, until you reach the watermark at the top of the pot.
The entire time you do this the plant is growing upwards and bit by bit you have been promoting root growth at the rising base of the stem, giving you a healthier tomato plant.
Common tomato plant problems
The main pests and diseases that affect tomatoes are whitefly, aphids and tomato blight. It is important to look out for yellow and curling leaves or rotting fruit as a sign of these.
It is best to try and prevent blight outright by keeping leaves away from the soil and also keeping the leaves as dry as possible.
If you find whitefly or aphids on your plant try washing them off with water. You can also plant marigolds which will attract natural predators such as ladybirds which will eat the pests. Read below for specific information on all of these:
Tomato blight is a fungal disease that rots the leaves and fruit.
The symptoms for tomato blight are that the leaves will start growing brown and curl up. The more serious forms of blight will also turn the fruit brown and cause them to rot. There are few effective treatments of blight and if you can your best option is to prevent it before your plants get it.
If your tomato plants already have it then you should quickly throw the plant away in the recycling, or burn it. Do not use that soil again to grow tomatoes. The same disease that affects tomatoes also affects potatoes so it may be necessary to also dig up any potatoes who have been growing and suppose of them as well.
Blight is caused by moisture on the leaves and stems. That is why it is important to only water the base and to prune any leaves near the soil so the water doesn’t splash up and potentially infect them. If you can, try watering your plants in the morning as this will give the sun enough time to evaporate the water away but not burn the plant.
Whiteflies look like small white moths and are most commonly found on the underside of leaves. If left unchecked they will feed on the leaves and turn them yellow.
Your best, natural defence against whitefly is to simply spray your plant down with some water, aiming it at the whiteflies to try and wash them off. Make sure you check the whole plant and get as much off as possible. If the problem persists you can buy a special bug spray that specifically targets these pests and is safe to spray on your tomatoes.
You can also plant companion plants such as marigold near your tomatoes. Marigolds deter whiteflies as well as attracting ladybirds and hoverflies which will come and actually eat the whiteflies.
Aphids are small green bugs that cluster on the stems, particularly at the joints, and also the underside of leaves. They cause leaves and fruit to discolour and misshapen. Aphids also leave behind a sticky residue known as honeydew which can then promote the growth of a fungus known as sooty mould.
Like whiteflies, ladybirds and hoverflies enjoy eating aphids so planting marigolds nearby will help control the pest. Also, the same chemical sprays that work for whitefly tends to also work against aphids. You can also use soapy water to try and wash the aphids off of the plant.