Growing Tomatoes – Starting Off Your Seeds

Most people start their tomato plants off from seed, which isn’t particularly difficult to do. The advantage of growing from seed is that you have access to a much wider choice of varieties. When you buy pre-grown plants you can usually only find a few of the most commonly grown varieties. Pre-grown plants are useful though, so please don’t dismiss them. If you find you have extra space, seeds fail to germinate or young plants die (usually a cat related incident in my household), then pre-grown plants are the perfect solution so you still get a crop of tomatoes.

When and Where to Start
Tomato seeds are always started indoors, unless you live in a very hot climate. Whether they are under lights, in a greenhouse or on a window ledge, starting them indoors gives your plants a head start so they can mature during the growing seasons. Depending on the variety it can take anything from 70 to 80 days and up to 100 for a plant to fruit from sowing the seed. In more northerly areas, the outdoors growing season may not be long enough to allow the plant to mature and the fruit to ripen.

Tomato Seedling Picture

Young plants are kept indoors until the risk of frost has passed, if you are planting them outdoors. During this time, you keep transferring them to larger and larger pots until they are ready to plant out.

Tomato seeds need a temperature of between 60-80F/15-27C to germinate, which can be as late as midsummer in temperate climates, which is far too late for the tomatoes to mature fully. In most areas, tomato seeds are sown between the end of January and April, depending:

  • How long the growing season is where you live
  • The time to mature of the variety you are growing
  • The space you have to keep the plants while waiting for the risk of frost to pass

If you do not have a lot of space indoors for the plants then look at growing a short season variety and starting in March or April so they have to spend less time indoors.

Remember, though, when you are transferring your tomato plants from indoors to outdoors to harden them off fully otherwise they suffer from transplant shock. This can stunt the growth by anything up to a month, which could mean the fruit do not have the time to ripen or, in the worst cases, kill your plant completely.

As a rough rule of thumb, start your tomato seeds between six and eight weeks before the average date of the last frost. Remember, tomatoes originated in the tropics, so love warmth and cannot survive in the cold.

Look up your last frost date online on a site such as this or this one for the UK. Count backwards six to eight weeks from the date it provides you and you know when to start your tomato seeds!

Start your tomatoes off in a good quality seed compost. Buy the best you can afford as the cheap composts tend to be more lumpy and do not drain as well, which can cause the seeds/seedlings to rot. Either grow in individual pots (I start mine in 3″ plastic pots) or in cell packs. Sow a single seed per cell or pot. Some people sow two seeds per pot and remove the weaker of the two, but I sow one per pot as I can’t cope with having to destroy a perfectly healthy plant and they are often too tightly entwined to separate.

You can buy peat or cardboard pots, but I don’t recommend these as in my experience they tend to dry out far too quickly or become too wet and grow moldy.

I like to mix the compost with perlite or vermiculite because it helps the soil retain water better plus helps prevent the compost from becoming waterlogged.

The three main steps in sowing tomato seeds are:

  1. Fill the pots with compost until there is 1/2 inch of space between the top of the compost and the top of the pot. Place one (or two if you prefer) seed(s) in the middle of the pot.
  2. Cover with a quarter inch of soil and lightly press down on the soil – the seed needs to be in contact with the soil to germinate successfully
  3. Carefully sprinkle with water – use a small watering can with a fine rose or use a spray bottle set on mist. Spray whenever the top of the compost looks dry; but don’t keep the soil soggy as the seed can rot
    1. This video shows me planting some tomato seeds in a mini propagator:

      This short video is watering in the seeds:

      Once this is done, place the pots in a sunny window or greenhouse, where they get at least four hours of sun per day; though more is better. The seeds need warmth to germinate, so many people will use grow lamps or heated mats/propagators to ensure a high germination rate. I’ve covered my pots with plastic wrap or plastic bags which acts like a mini-greenhouse, though you do need to keep a close eye on your pot that it doesn’t dry out or get too soggy. As soon as the seed germinates, remove the cover otherwise the seedlings could die due to damping off disease, which is a problem with tomato seeds. Using a small fan to circulate the air can reduce the risk of this disease. Be careful about opening a window as the cold air could hinder germination and growth.

      Tomato Seeds Mini Greenhouse Picture

      When your seedlings have two true leaves, then it is time to transplant them to a larger pot. We’ll talk about that more in the next edition of this series as well as discuss the hardening off process and more.

      Discover everything you need to know about growing tomatoes in my new book, “Growing Tomatoes” available in paperback and ebook in the UK here and the rest of the world, including the USA here.

      growing tomatoes book cover

      Tray of Tomato Seedlings Image


Growing Tomatoes – Which Varieties To Grow?

There are a bewildering amount of tomato seeds on the market in all sorts of shapes and sizes. There are tiny tumbling tomatoes no larger than your fingernail, sweet cherry tomatoes, meaty paste tomatoes, juicy salad tomatoes, and the giant beefsteak tomatoes. Not only do you have this choice, but there are lots of different colors available too, not just the commonly found red tomatoes! Now you can buy tomato plants that produce fruit ranging in color from orange to yellow, green, purple, chocolate, black and deep crimson.

Tomato Seeds

Ready to plant some tomato seeds

With over 3,000 varieties of heirloom tomatoes actively cultivated and over 15,000 known varieties, it can be very difficult to decide what to grow.

Firstly, decide whether you want to grow from seed or buy pre-grown plants. If the former, then you have a much wider selection as the pre-grown plants tend to be the same few varieties such as Gardener’s Delight or Moneymaker. Occasionally you may find more unusual varieties such as a yellow tomato or Tigeralla or even a black tomato, but these are much harder to find.

Colored tomatoes

Colored tomatoes

When growing from seed, you need to start your plants now or in the next month so that they have time to mature, fruit and ripen. If you are in a colder area with a short growing season, it is important to start them off indoors early so they are fruiting and ripening when the weather is right for them. Pre-grown plants can be bought much later in the season around the time, or just after, the last frost. Remember, tomato plants are not frost hardy!

Be adventurous with your choice of tomatoes, don’t just grow the same tomatoes you can buy in the store, choose some varieties that are unusual, different and not available from the shops. I have my favorite varieties, but every year I like to try one or two new cultivars that I’ve not grown before. Each year, new types of plant are brought to market, so there is always something new to try!

One thing to consider is whether to grow determinate or indeterminate tomatoes.

Determinate tomatoes are known as bush tomatoes. They grow up to about three feet tall, set buds at the end of the branches which form flowers. The fruit all ripens at once and then, usually, the plant dies back. These are great if you don’t have a lot of space, haven’t got the time to prune your plants, or you want a lot of fruit ripe at once to can or make into something. There are fewer varieties of bush tomato, but you can usually find a variety that is the size and color you want to grow.

Determinate tomato plant

Determinate or bush tomatoes are much smaller, requiring less maintenance

Indeterminate tomatoes are the type of plant people are most familiar with. These are the vining tomatoes that need supporting and grow like crazy. These have to be pinched out and will continue to produce fruit until they are killed off by frost. Indeterminate tomatoes produce very large crops of tomatoes over a longer period as the fruit does not ripen all at once. These are great for eating as you do not end up with a glut of fruit. Typically, you limit the growth of this type of tomato so that it can ripen the fruit.

Indeterminate tomato plants

Indeterminate or vining tomato plants grow very tall if not maintained

Whether you are growing in the soil or in containers will also influence your choice of seeds. Bush tomatoes are better suited for containers as their size is limited whereas indeterminate tomatoes need larger containers because they grow so big. Tumbling tomatoes are excellent for hanging baskets and make for a striking, edible display.

Which you choose to grow is up to you. I recommend picking some you like, so if you regularly buy cherry tomatoes or salad tomatoes, grow some of those. Instead of growing a normal red cherry tomato, grow a yellow cherry tomato such as Golden Gem or a pear yellow tomato such as Nugget or an unusual crimson tomato such as Midnight Snack.


If you fancy something more unusual, try growing Cherokee purple for giant, beefsteak tomatoes that are a lovely shade of purple. Big Rainbow is another beefsteak variety worth growing due to its unusual striping. One of my favorites is Mortgage Lifter, which are giant red tomatoes. They got their name from the farmer who developed them. He was on the verge of losing his farm when he developed this variety of tomato which he sold at markets. It was hugely profitable for him and he was able to pay his bills and save his farm, including paying off his mortgage, hence the name!

There are lots of varieties out there and you will even find that different seed companies stock different varieties plus may have exclusive varieties. Choose some that you like and pick one or two varieties that are purely for fun, as an experiment; you never know, you may find a new favorite tomato!

Tune in to the next installment to find out the difference between F1 and Heirloom tomatoes and to learn what you need to start your tomatoes off!

Discover everything you need to know about growing tomatoes in my new book, “Growing Tomatoes” available in paperback and ebook in the UK here and the rest of the world, including the USA here.

growing tomatoes book cover