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How To Grow Tomatoes

Many gardeners start tomatoes indoors and sow tomato seeds early in the year. After that, most gardeners will transplant tomatoes to their gardens once the weather warms. But with the correct methods and care, you can grow tomatoes indoors to harvest time inside your home. 

Growing Tomatoes Indoors

Growing tomatoes indoors successfully involves thinking carefully about:

  • Where to grow tomatoes and in what. 
  • Which tomato variety or varieties to grow. 
  • How to germinate tomato seeds successfully.
  • How to care for your growing tomato plants indoors.
  • And how to harvest, and make the most of the tomatoes you grow. 

Where to Grow Tomatoes Indoors

Some vegetables to grow in an indoor garden are far less fussy and easier to grow than tomatoes. Tomatoes are sun-loving plants that need as bright and light a spot as possible to thrive. So low light levels inside a home can be a major challenge when trying to get indoors tomatoes to flower and set fruit. 

It is best to use grow lights to make sure that tomato plants get the light they need, whether or not you are later transplanting the tomato plants to an outside space. 

Tomatoes need more light than they will usually receive indoors early in the year while they are young seedlings. And light is also crucial to achieving worthwhile yields of fruit. 

Seedlings grown in low light conditions can get leggy and weak. And later, tomato plants that don’t get enough light will not fruit as well, and may not fruit at all. 

Unless you have an extremely bright, south-facing conservatory or glass-covered porch, and live in a sunny location, grow lights will usually be essential when growing tomatoes indoors. 

As well as thinking about light, positioning tomatoes correctly also involves thinking about temperatures and humidity. Tomato plants need a warm spot, without extremes of temperature, and moderate humidity levels to produce the best yields.  

Make sure you do not place your growing area close to heat sources or in a draft from a door or window. But ensure too that there is adequate ventilation and airflow to prevent a range of potential problems. 

Tomatoes in your chosen location might be grown within a wide range of different containers. 

You might choose simple pots for the purpose (a pot around 40cm wide, or a 5-gallon bucket is ideal for a tomato plant growing to full size). You will typically start tomatoes in seed trays or small individual pots, and pot up as required before they reach their final container. 

Tomatoes can also be grown in hanging containers, in hydroponic or aquaponic systems, or using other eco-friendly growing methods indoors. 

Choosing Tomatoes to Grow Indoors

When choosing tomato varieties to grow indoors, there are several things to consider:

  • Select heritage varieties that are not readily available in the store and you will surely appreciate every tomato you grow, even when you can’t grow that many of them. 
  • Look for determinate (bush tomatoes) rather than an indeterminate (cordon tomato) type. These are usually smaller, more compact, and easier to manage indoors. The word ‘patio’ or ‘bush’ on the label will tell you that this could be a good, smaller choice. 
  • Cherry tomatoes, grape tomatoes, or smaller Roma tomatoes are generally easier to grow to a successful harvest indoors. The fruits will be small but can be very sweet.
  • There are both upright bush and tumbling types of tomato. Small tumbling types are fantastic for hanging containers, while small bush types work well in a range of pots. 
  • When choosing tomatoes, think about choosing companion plants for your container garden too. Tomatoes will thrive when they are planted in a container alongside basil, for example. This is a famous companion planting combination. 

Sowing Tomato Seeds

Once you have selected your tomato variety or varieties, of course, it is time to sow seeds. You can also purchase plug plants but sowing tomato seeds is well worthwhile and not too challenging as long as you understand what is required to germinate tomato seeds successfully.

Tomato seeds are sown sometime between January and April. To achieve good germination rates, tomato seeds need:

  • Temperatures between 16 and 30 degrees Celsius. (A heated propagator is often beneficial to provide the right temperatures and improve germination rates.)
  • Water. Make sure the growing medium into which you sow tomato seeds is moist but not waterlogged. 
  • Oxygen. Make sure the potting mix you use is light, and aerated, not waterlogged and compacted. 

Make sure you use viable seeds, that have been stored correctly, or germination rates may be poor. 

Tomato seeds should germinate and sprout successfully within a week or two. 

Caring for Indoor Tomato Plants

Caring for a tomato plant involves thinking about:

  • Watering. The growing medium should be moist but free-draining. Do not allow it to dry out entirely or become waterlogged. As you water, try not to water the foliage, flowers, or fruit. Direct water to the base below the plant, where it is needed. 
  • Pricking out and potting on as needed. It is important not to leave tomatoes where their roots are too constricted or they can experience a check in their growth which can influence yield.
  • Pollination. Tomato plants grown indoors cannot be insect-pollinated as easily. So often, you will have to take a small brush and take pollination into your own hands to achieve a good harvest of fruits. 
  • Feeding. Tomato plants should be given an organic liquid feed high in potassium every couple of weeks when watering while it is flowering and as fruits mature. Comfrey tea is one great organic feed to consider. 

Of course, you also need to look out for pests and diseases, as remaining vigilant means you can nip potential problems in the bud before they become major issues. 

Harvesting Indoor Garden Tomatoes

Once tomatoes are ripe, soft, and fully colored, they can of course be plucked from the vine. 

The tomatoes grown indoors are often best used for salads and fresh eating. But you might also use them in a range of different ways, in cooked recipes and even, if you grow enough – in preserves to place in your pantry.