How to grow tomatoes indoors with Full Spectrum LED grow lights

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Tomatoes are very versatile fruit, that are great as a main meal when turned into a sauce, or as a side dish. Imagine if you could have fresh home grown tomatoes all year round.

Preserving and Fermenting are both ways to keep a supply of tomatoes at home all winter. It is possible however to grow tomato plants all year round under the right conditions, and using the right equipment. With LED lights and a warm environment, you can grow tomatoes indoors all winter.

Where should I grow my tomato plants indoors?

Firstly I would suggest finding a window, or if you are just going to use lights, somewhere that will have a relatively constant temperature during the winter months. South facing windows are a good option, as even during Winter they often will have some light. If you are in the northern hemisphere that is.

How to choose an LED grow light for growing indoors

LED lights, or panels come in all shapes and sizes. For plants that produce fruit, like tomatoes it is best to invest in a Full Spectrum LED grow light.

Smaller plants such as Lettuce, Basil, and Dill for example are happy to grow under a White LED light that is just one colour temperature. This is normally somewhere between 6000K to 6500K, or a White light. These are all plants that produce only leaves, so White light is beneficial for them to increase growth.

Full spectrum means that the grow light is made up of different temperatures and types of LED chips, that your plant will use during different stages of growth.

How different temperature light helps plants in different stages of growth

  • Blue/White Light 5000K and above - This Blue or White light (5000K-6500K), helps to promote germination of seeds, and increase growth rate.
  • Warm White Light 3000K - This is a warmer orange, yellow light. This will help your plant to blossom.
  • Red Light 660 nm - This in combination with Blue to White Light above will help with increasing your yield of leaves, and eventually fruit.
  • IR Light 760 nm - Infrared light allows the plant to produce a greater yield.

Do I need a big space to grow tomato plants indoors with an LED panel

You need to consider that in order to grow tomato plants from seed to producing fruit, they will be tall if using indeterminate varieties. Also the LED panel or light will need to hang above them and be able to be adjusted as the plant grows. So account for a little head room above your new growing space.

LED lights are beneficial in many ways. One way is that they do not produce much heat. Having said this if your leaves, flowers or fruit do get very close or even in contact with the panel, it can cause damage.

LED panels normally come with everything required to rig them up so that they are height adjustable. This is very important, and will need to be monitored in order to keep your plants healthy, and strong.

High quality LED panels will also include a dimmer switch or dial which is very useful when growing from seed. Based on a 100w Full Spectrum LED panel with dimmer switch it is recommended that you set the intensity as follows.

Intensity of Full Spectrum LED panel with dimmer for each stage of growth

  • Germination - 20-40%
  • Seedling - 40-60%
  • Vegetative - 60-90%
  • Flowering - 90-100%

The ability to control the intensity and the height of the LED panel will give you much greater control and confidence that your plant will survive to produce fruit.

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How hot do I need to keep the space where my tomato plants are growing

Tomato seeds germinate best at around 25 degrees Celsius, and normally take somewhere between 5-12 days to do so.

This could be much longer depending on the age and variety of your seeds. Do not worry if it is taking longer.

The LED panel should help to keep the temperature up a little, and you can adjust the height of it so that it is fairly close to the seeds, 10 cm to 15 cm should be good to raise the temperature enough to keep the seeds happy, and to encourage germination.

How much Light do Tomato plants need indoors

Providing your new plant with enough light is very important in order for the plant to get enough energy to produce fruit and grow big and strong.

It is equally important to provide your tomato plant with enough Dark. Having a light schedule is very important, and any LED light that you get should be on a timer to provide the plant a day and night cycle.

Tomato plants, once they are established and growing leaves will thrive best with around a 12-15 hours per day of light. The remaining dark period (or night cycle) will give the plant time to properly adsorb carbon dioxide which it will use during photosynthesis. This Day and Night cycle will make for a healthy plant, and a higher yield of fruit.

Which LED panel or grow light should I buy to grow Tomatoes indoors

There are lots of options out there, and unfortunately lots of imitations. LED chips are replicated easily, and it has made for a very confusing market with Lots of options, and opinions.

We have been growing tomatoes indoors with a simple Hydroponics system, and an LED Panel now since early February this year (2020), and the results have been astounding. The tomato plants quickly took over the kitchen, the chilli plants, and salad followed swiftly behind. The next group of crops will need a dedicated area to grow in, so that the plants have plenty of room to grow, flower and produce fruit.

An LED Grow light that I would recommend is this Full Spectrum LED grow light urban grow FS110 LED Grow Light. This is a great option for growing all kinds of indoors plants, and edibles indoors all year round. With a range of LED chips including 3000k, 5000k, 660nm, IR, and UV. This gives your plant every bit of the light spectrum it needs to get from seeding to vegetative, and even flowering.

This LED Grow Light Strip has many other advantages, and it can transform to help you during the various growing stages, right from seed to harvest. At 110 cm long, it gives you great options for hanging above a large range of seed trays, as your plants start their life, then as your tomato plants get larger these lights can be transfered into a grow tent for example, to keep your plant growing right through flowering and fruiting.

It can also be daisy chained up to 50 times using 1 x power cord (when using a 230V power supply), which makes it a great option for growing using shelves, or a larger bench of tomato varieties.

Alternatively, the Spider Farmer SF-1000 Full Spectrum LED Grow Light (opens in new tab) uses Samsung LM301B diodes, and a Dimmable MeanWell driver. The SF-1000 Spider Farmer LED panel is capable of growing commercial amounts of plants. It can be linked with other panels in the range via RJ45 Cable, and support up to 12 lights. This is a great option to have if you ever wanted to scale up your indoor growing.

Growing fruit such as tomato plants indoors during winter is very achievable, and can help you to keep eating fresh produce all through the year. This will give a great boost to your health, your wallet, and any concerns about air miles put on food in larger shops during the winter months.

Using some links in this article will get you a 3% discount on Spider Farmer products, from Epic LED Grow Light. They ship all over the world, and have locations across Europe. The button below has the discount applied already.

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Ian Hunter

Ian Hunter - Father of three, based in Southern Sweden. Author and Co owner of Grow Zone and growing Food all winter. See my full About Page here.

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