How to Grow Tomatoes from a Tomato

Originally from South America, the trusty tomato has become a staple in salads and burgers around the world are instantly recognised for its bright red colour. The lush red fruit (classified as a berry) is extremely versatile and can be prepared and eaten in many ways. They can be eaten raw or cooked or even pulped and made to drink and they are also commonly used as a vegetable.

There is nothing better than eating something that you have grown yourself and we are often asked how to grow tomatoes from a tomato so we have put together this comprehensive guide so you can enjoy the fruits of your hard work – pun definitely intended.

How to Save Tomato Seeds at Home

Saving your own tomato seeds makes the process of growing all the more fun especially for the kids. The kids can easily muck in and help you and will have a great time whilst doing so. The beauty of it is that they will be learning about the juicy red fruit at the same time.

What you Need to Save Tomato Seeds

A Few Ripe a Juicy Tomatoes

1 Sharp Knife

1 Jar

1 Teaspoon

3 Sheets of Kitchen Roll

Step 1. Choose the Best Tomatoes

If you have already grown your own tomatoes, you should choose the best and healthiest looking tomatoes to take the seeds from. However, if you are like me, you will want to eat the best and the brightest on the vine, you can buy some fresh tomatoes from the supermarket and the seeds will be just as good.

Choosing the best tomatoes

Step 2. Harvest the Seeds

Slice your tomatoes and scoop out the jelly that contains the seeds and store this in a jar for four or five days at room temperature. 

The jelly will begin to go mouldy but do not worry, that is what we want as it will help us remove the jelly which can prevent the seeds from germinating.

Harvesting Tomato seeds

Step 3. Clean the Seeds

After 4 or 5 days the jelly should have started to go mouldy meaning that the seeds are ready to be cleaned. 

Using a sieve, you should thoroughly wash the seeds ensuring that all the mould has gone.

cleaning tomato seeds

Step 4. Dry and Store ready for Spring

Place your seeds on a little kitchen roll until the seeds have completely dried out and then store them away in a cool, dark place until they are ready for planting.

You could wrap them in some kitchen roll or put them in an envelope. As long as they are safe it will be fine.

tomato seeds

When to Start Tomato Seeds

In the UK, tomatoes are generally grown in greenhouses as they love the warmth and do not tolerate frost. You can buy some small seedlings from the garden centre but where is the fun in that! The best way to experience the full enjoyment of growing tomatoes is to do it from scratch. It is so easy that kids can do it too.

You will want to start germinating your seeds around 6 weeks before the last frost and to do that there are a few things that you will need.  

Seeds

First, you will need the seeds that you have prepared as we have mentioned above. They should be nicely dried out and clean. If you have decided to purchase seeds instead of preparing your own, ensure you choose the type of seeds for the type of tomatoes that you want. There are hundreds of varieties to choose from; cherry tomatoes that are great with salads or specific tomatoes that are great for making sauces and pastes.

Another thing to consider is how big the plant may grow. Some tomato plants will only grow to around 3 feet whereas others can grow to 6 feet!

Soil

The type of soil that you choose is important to give your plant the best start in life. We recommend using a specific potting mix that is labelled for seed starting. The odd thing is that this mix usually contains no actual soil at all!

Do not just use soil from the garden, soil from the garden can be devoid of nutrients and may contain nasties that will affect the growth of your plant.

Pots

You will need some small pots to start your plants. Recycled yoghurt pots are a great substitute as long as you create some drainage but we are going to share with you our favourite way to start our tomato seeds and that is by recycling biodegradable egg trays.

Light & Warmth

Tomato plants are heat lovers so for best results we recommend that you use a dedicated seed starter light (amazon link – opens in a new tab). If, however, you do not want or are able to invest in a seed starter light, you should find a warm windowsill that gets the sunlight for most of the day.

How to Start Tomato Seeds

Like we mentioned previously, we are going to share our favourite way of starting tomato seeds using an egg tray.

We find that egg trays are perfect for growing tomato seeds. Each egg cup is the perfect size for each little seedling and it also makes things much easier when transplanting into bigger pots. All you need is a spoon. Read on, and you will soon see what I mean.

Adding the Soil for Tomato Plants

We fill our egg tray with potting mix ensuring that it is not too tightly packed (packing the soil too firm will impede your seedlings development).

Sowing Tomato Seeds

Now we will sow our tomato seeds. We will get a toothpick and for each egg cup, we will make 3 small holes in an evenly spaced triangle around 4-5mm deep. 

Then we will add 2 seeds into each hole (a folded piece of paper works best for sowing the seeds), you will see why we add 2 to each hole in a minute.

Moisten & Cover your Tomato Seeds

Next using a spray bottle we will moisten the top layer of the soil being careful not to overwater and soak the seeds and then we will cover.

Evenly place some blunt end cocktail sticks into the soil and cover with clingfilm. The cocktail sticks will act as supports for your little plastic roof.

Heating your Tomato Seeds

At this point, your seeds do not need any light however they will need warmth. If you are using an LED grow light, this will provide the warmth that you need and the clingfilm will help to hold that warmth in the soil.

If you are using your windowsill, ensure that it is getting maximum heat from the sun throughout the day and continue to ensure that the soil remains moist by spraying each day.

Tomato Seedlings First Growth

Around 5 or 6 days later you will begin to see some signs of your seeds sprouting. Sprouting times can vary, I have seen some sprout after just a few days, others have taken a fortnight and some not at all!

Culling your Tomato Seedlings

Once most of the seedlings have reached about 4 cm tall, it is time for a cull. You will want to choose the strongest looking plant from each cup and any seedlings that have come through looking weak and spindly compared to the rest should be culled; these little ones are not likely to go the distance.

Be careful not to damage the one from each cup that you want to keep and do not yank out weak looking plants as that will disturb the roots of the others.

Tomato Seedlings True Leaves

At around day 10 after sowing, you should start to see the first pair of true leaves. The first 2 leaves that had grown are called seed leaves and are like a solar panel to get as much sunlight as possible until the true leaves begin to form.

Once the first true leaves have fully formed, the seed leaves will wither and fall off. This is normal and is also a good indicator of the next stage and that is transplanting the seedlings into bigger pots.

How to Transplant Tomato Seedlings

Next up, we will transplant the seedlings and it is crucial that you get this part right.

Once the first pair of true leaves are fully formed, the stem should be starting to thicken and grow little hairs. This is when you will want to transplant your tomatoes into 3-inch pots, and this is where the beauty of using our egg cartons comes in.

  • Place about half an inch of potting soil in the bottom of the pot and using a spoon, dig out each seedling from the egg cup and gently place in the pot.
  • Next, gently backfill the pot covering most of the stem. When you do this, all those little hairs below the soil will turn into roots giving your plant a strong base from which to grow.
  • Once you have your little plants in their pots, you will be able to water. When they are this small, we like to use a bottle with a sports cap just to give the plants a little drizzle each.
  • Water regularly for approximately the next 4 weeks and then your young tomato plants are ready to be moved a more permanent place.

Planting Tomato Plants in the Garden

By now, with it being around 6 weeks after sowing and the last frost has (hopefully) passed, your tomato plants should be growing well making it time for planting your tomato plants in the garden.

Where to Plant Tomato Plants in the Garden

As we have mentioned above, tomatoes are sun lovers. You will want to plant your tomatoes in a warm and sheltered place that gets the sun throughout the day. Also, Tomato plants will do well on a border backed up by a wall or fence which will offer much-needed shelter & protection.

How to Plant Tomato Plants in the Garden

Around 2 weeks prior to planting in the garden, you will need to prepare the ground where the plants will be going. You will need to dig over the area thoroughly and work in some well-rooted manure or garden compost.

Once you are ready to plant your young tomato plants, you will want to dig a hole with a depth around an inch deeper than the pot that the plant is in. Gently hold your pot upside down with the stem between your fingers to catch the soil ball and gently knock being careful and keeping the soil ball intact.

Place the soil ball in the prepared hole and backfill, firming the area around the stem. You will want to space plants around 45cm apart and if you have more than 1 row, keep each row approximately 75cm apart.

If you are unsure of which variety of tomato you are growing it is good practice to ensure that as soon as you have planted, you stake the ground to give your plant added support. Place your stake into the ground next to where the soil ball is located and loosely tie your tomato plant to it. Bamboo stakes are pretty useful for this!

Wrap some garden string around your bamboo stake twice making a loop around your tomato plant. You will need to do this very loosely to ensure that your plant has plenty of room for growth.

How to Plant Tomato Plants in Pots or Containers

If you do not have a suitable place in the garden for your tomatoes and you are planting into pots, you will want to plant your tomato plants into 10-inch pots.

Fill the pot with enough compost so that when you place it in your soil ball, the top of the ball is 3 inches off the top of the pot. In much the same way as when planting outside, you will want to backfill the pot and firm the soil around the stem. Then you will want to stake the plants in the same way as we have mentioned above and water well.

How to Take Care of Tomato Plants in Pots or Containers

Tomato plants that are in pots will require much more watering than tomatoes planted in the garden. Tomato plants will require watering at least once a day and in particularly dry weather, they may need watering twice. It is also advisable to add a liquid tomato fertiliser to the water as per the manufacturer’s guidelines.

How to Prune Tomato Plants to Maximise Tomato Crop

The reason that we are growing tomato plants is for the fruit and there are a couple of techniques that will help in the growth of the fruit. If you follow the guidelines we have set below, you will soon have a fantastic crop to harvest.

Removing Side-Shoots

As the plant grows, it will begin to form new side shoots within the leaf axils. You will want to pinch these off before they reach and length of around 1-inch as we do not want the plant to expend energy on creating more greenery, we want it to bear fruit. These can be easily pinched off with your finger and thumb, but we recommend using a clean sharp knife.

Cutting the Top of the Plant

Another thing that we do to aid the growth of our fruit is to cut off the top of the plant. When the tomato plant has at least 4 trusses of fruit, we recommend cutting off the growing point leaves above at the top of the plant. Again, by cutting the plant above the top truss, we are hindering further growth of greenery, therefore, aiding the swelling of the fruit.

Growing Tomatoes in Grow Bags

Another great way of growing tomatoes is by using specialised tomato grow bags (amazon link – opens in a new tab). Tomato grow bags can be bought in most garden centres and are filled with balanced peat-based compost and all the nutrients you need to get the best out of your plants. All you need to do is add your young tomato plants and water them.

Planting Tomatoes in Grow Bags

  • Lay your grow bag flat on the ground, preferably in the place where it will stay so not to disturb the plants as they are growing. (Remember they love to be in the sun all day.)
  • Cut a long thin rectangle in the centre of the grow bag ensuring that it is still wide enough for you to water.
  • In a straight-line plant 4 of your young tomato plants per bag.
  • Stake the plants as you would have if you had planted in the garden or in pots.
  • Water well although the bags have no drainage so be careful not to overdo it.

How to Harvest Tomatoes

You can pick your tomatoes as soon as they ripen. The easiest way is to press the swelling just above the fruit between your finger and thumb and the fruit will break away cleanly. If, however, your plants have not ripened by the end of the summer season, you can help along the ripening process.

How to Ripen Tomatoes

If your tomatoes are still a little green at the end of the season, you can aid them in ripening by cutting whole trusses and leaving them on a well-lit windowsill. 

They will soon ripen and be ready to eat!

What can go Wrong with Tomato Plants

Like most plants, there is a variety of things that can go wrong with your tomato plants. From underwatering through to diseases and those pesky little bugs that want to enjoy eating your plant. Below we will have a look at a few things that could go wrong with your tomato plant.

Insects

You are not the only one that wants to eat your tomatoes, there are numerous insects that you must watch out for. These little critters are all vying for a piece of your well-earned fruit and they are not paying customers!

Greenhouse Whiteflies

The tiny Whiteflies will literally suck the life out of your plants. The Whitefly is a pest that feeds on the plant’s phloem which is used to transport the nutrients around the plant. There are a few different ways to control the population of Whitefly including organic pesticides and even introducing natural Whitefly predators.

Spider Mites

These tiny little red spider mites also eat the sap from your plants and a large infestation can do serious damage to your plants. Often when you have a serious infestation the plants can be covered in silk webbing.                                                                     

Aphids (Blackfly & Greenfly)

Aphids are another little critter that will feed on your plants in much the same way as the Whitefly. Aphids can be controlled by regular washing of the plant.                                                           

Leaf Mould

Leaf mould is caused by a fungus and you can recognise it when the upper sides of the leaves have yellow blotches and there is a brown mould underneath.

Prevention

The best prevention for this is to purchase disease-resistant seeds.

Cure

You are not the only one that wants to eat your tomatoes, there are numerous insects that you must watch out for. These little critters are all vying for a piece of your well-earned fruit and they are not paying customers!

Virus Diseases

This can be recognised by stunted plants and mottled leaves that are distorted and streaked.

Prevention

Disease resistant seeds. Controlling Aphid and Thrip populations that can spread the diseases.

Cure

None. Destroy the plants by burning.

Good Practice

A good and regular hosing of your plants is a good way to keep down pest populations. Make sure to do it in the evening when the sun has gone down.

Keeping your plants well-watered is also a good idea as insect infestations are more prevalent in drier conditions.

We prefer not to use any pesticides unless it is absolutely necessary. Pesticides no matter how harmless to humans will have an effect somewhere in the food chain.

Summary

I hope you have enjoyed the article and now you have an idea how to grow tomatoes from a tomato. There can be a few obstacles but do not let that stop you as tomatoes are really quite easy to grow and when you get to eat them at the end, you will realise that it has all been worth it.

Tomatoes are also a great plant to help teach kids about nature and growing things and there is no time like the present, you can start right now and go and start saving your seeds!

You should also check out our article on How to Grow Potatoes – The Kids will Love it!

Garden Doctor Trev

Garden Doctor Tips

“If buying tomatoes from a supermarket to harvest their seeds – make sure they are organic!”

“If you are planting your tomatoes into Pots, we recommend using John Innes No.3 compost!”

“If you are planting in the garden, prepare the soil around 2 weeks prior. Dig the ground over thoroughly and add some well-rotted manure or garden compost!”

“When using grow bags allow 6 trusses of fruit although if you want lots of smaller fruits, you can allow as many trusses as can be!”

Frequently Asked Questions

Can you Grow Tomatoes in Winter?

Tomatoes can be grown in the winter although they will need sufficient heat and light. This can be achieved with a heated greenhouse and the right lights, but this can be awfully expensive due to the energy expenditure required. We recommend that you grow your own tomatoes in a regular way and plant them in the spring after the last frost.

When should you plant Tomatoes in a Greenhouse?

Unless you have the luxury of a heated greenhouse, you should wait until after the final frost before planting your seedlings in a greenhouse.

What are the best tomatoes for tomato juice?

Any tomatoes are the best for tomato juice. There is no individual variety that makes the best for juice. Many people will recommend that you use a mixture of varieties for your juice to make the juice more flavourful.

What is the best fertiliser for tomato plants?

The best fertiliser for tomato plants is Miracle-Gro Water Soluble Tomato Plant Food. This plant food has been specially designed to include the right nutrients to ensure you get the most out of your tomato plants. The great thing about this fertiliser is that it can be used on a variety of other plants and vegetables in the garden!

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