Growing Tomato from Seed (The Right Way)

It might be quicker and easier to buy a plant from the local Garden Centre,
but is it as rewarding? We think not, so this guide aims to inspire you to venture into the world of growing from seed.

The Basics

Maybe last year you bought a plant from the local garden centre and enjoyed a few tomatoes, but you want more and fancy trying to grow from seed and generate a larger crop this year. Maybe it’s time to buy yourself a propagator?

As you know, a single plant might get big but can only yield a certain amount of tomatoes, so grab yourself a pack of seeds, whichever variety suits you (or a selection of varieties) and let’s get started.

First Step (Buy a Pack of Seeds)

Visit your local garden centre, farm shop or even order them online. Buy a single pack of seeds or a multi-pack, like the one below.

Expect to pay between £2 and £5 for a pack

Time to Start

You will need 6 – 8 weeks of growing inside before the plants will be strong enough to move outside. The ones below have just been taken from the propagator (shown above) and are being re-potted and held in a cloche outside. They are not strong enough to brave the elements yet.

Pots and Compost

You are going to need some potting compost, suitable pots and some space to grow inside.

Choose a good quality seed compost and use a small pot or seed tray, sprinkling a few seeds onto the surface of each pot. 

Fill the pots with a suitable soil and drop a couple of seeds into each pot. Cover the seeds with a thin layer (about 1.5 – 2mm) of compost.

Water carefully with a fine-rose watering can, taking care not to disrupt the seeds.

How long does it take for Seeds to Germinate?

In the UK seeds usually germinate within 7 – 14 days, if they are kept at a temperature of around 21 degrees.

Mist the seeds daily for the first 7 to 10 days.

When you start to see sprouts, you can water less frequently. More plants are killed by too much water (that rots the roots) than too little water so water sparingly after the plants sprout.

You can regulate the heat by using a propagator, which provides the ideal growing environment to encourage seeds to sprout into seedlings.

These are generally shallow trays with just enough soil for seeds to grow. They may be covered to lock in windowsill warmth and keep the soil damp, while others are electrically heated at a low, steady wattage.

Seedling Progress

Once germinated, the first leaves that appear are the baby cotyledon leaves. These leaves are followed a second set, known as the ‘true leaves’.

It usually takes around 30 days for the plants to get to this point, depending on the amount of sunlight.

At this point, the seedlings are ready to be transplanted into larger pots.

Transferring Seedling to Small Pots

Do not be tempted to plant straight into the original tomato grow pots as they are not quite big, or strong enough yet.

For now, you need to be moving the seedling plants into something a little bigger to enable growth, still keeping the plant inside.

They are not ready to handle the outside elements quite yet.

Increase Pot Size as Plant Grows

A quality potting compost with fertiliser is preferable to use at this stage, perlite can be added to assist with retaining moisture as well as helping with drainage, about 20% is sufficient.

Fill a small pot with compost and make a hole in the centre where the seedling will be planted. Tomatoes can be planted down to the first set of leaves. Tomatoes plants grow roots from the stem so planting deeper will encourage good strong plants.

Tomato Sowing Period

Sow – February to April
Here in the UK the best time to sow indoors.

Plant out – May to June
After the last of the winter and late spring frosts

Harvest – July to October
Enjoy!