How To Grow Organic Heirloom Tomatoes in Soil and Hydroponically

How to grow organic heirloom tomatoes hydroponically and in soil.

How I Got Started With Hydroponic Tomatoes

In 2019, I took it upon myself to learn how to grow hydroponic tomatoes as well as grow them in soil. I spoke with my sister, who had some fairly extensive experience growing tomatoes on her property. So I thought, well, gosh, if she can grow tomatoes, I bet I could too. And it was done. I had made up my mind to try my hand at growing my own food, and tomatoes seemed like a great place to start.

Last winter was when this decision to grow transpired. I honestly have an issue with crappy winter weather, so I was looking for a way to keep my mind at bay while I tried to live through the horrid winter months here in Canada. So, I went out and bought some LED grow lights (see my Recommendations page for the review/link). I made a few designs of hydroponic setups in an attempt to determine what would work for me.

Here is a picture of my first hydroponic setup. I had initially intended to use this for micro-greens. I thought If I could cycle micro-greens every week, I could grow enough for my wife and me to have a steady supply of greens to eat.

Well, my design sucked. To put it lightly. I didn’t realize how weak the pump I had purchased was, nor did I realize how much the roots would eventually tangle and choke the system. But at first, it seemed like a great concept.

Learn how to grow organic heirloom tomatoes like this (my 2019 setup).

After the failure of my first hydroponic setup, I decided to forgo trying to grow tomatoes in this particular setup. One thing I learned, however, is that tomato seeds absolutely love germinating in a hot environment. And the seedlings love this climate as well.  

Seed Selection

One of the first and most crucial decisions to make before you get gardening is whether will you grow from seed or buy developed small plants. Despite the fact that I intended to do hydroponics, I chose to pick up organic tomato breed seeds only. I chose a slightly rare specialty breed of tomatoes, which were supposed to be multi-colored, and I thought would be neat to see grow.

I found an organic seed dealer and ordered WAY TOO MANY seeds. They were actually pretty cheap. I think I wound up ordering something like 1000 seeds. This was insane, as I only wound up germinating about 30 seeds.

Before you dive in and buy seeds, keep in mind a few things.  

  1. Tomatoes like it warm. The seeds LOVE germinating in a heated area around 80 degrees Fahrenheit.
  2. Tomatoes love the sun and lots of it. If you are going to try to grow indoors, you will NEED specialty lighting to grow indoors.
  3. Organic or Not? I always recommend natural organic strains. Why? I’m not sold on genetic modification as being safe. In my opinion, there just haven’t been enough studies done to determine safety. That and the cost to buy organic seeds really wasn’t much more than non-organic, so why bother with engineered ones? 

Tomato Seed Germination

There are two ways to germinate seeds. The old-fashioned way, which is the tried, tested, and true method, or to go experimental like a hydroponic tomato seed germination method. I’ve had success with each method. Depending on the strain of tomato or any plant you intend to grow from seed, for that matter, one method may prove to be more useful to you than another. For that reason, I’ve decided to go ahead and describe both methods I have used to germinate tomato plants successfully.

Standard Germination

The standard germination method for tomatoes is fairly straightforward. Let me tell you about the method that I used with heirloom organic tomato seeds.

To tell this tale of germination, let me give you a little background. I ordered way too many seeds to begin with. I’d never started tomatoes from seed before. And I had heard from several individuals that it was indeed a difficult task. So I ordered, I think, like 100 seeds. I thought, okay, if I try to germinate like 20 seeds and I get 10% of them, then I will have 2 plants. No problem.

I wound up having 18 plants from 20 seeds. And that is a lot of tomato plants, let me tell you. I’ve been eating pasta and tomatoes with toast for weeks. I’ve got tomatoes on top of more tomatoes. But I digress, back on point. Let’s get back to the germination.

First, take your seeds and lay them between two layers of clean paper towels. Then, pour warm, filtered water (preferably non-chlorinated) on the paper towel until it’s very wet but not pooling with water anywhere. Leave this in a warm place and keep it moist for 24 hours. Then, check on the seeds. 

Most of your seeds should germinate within 1-4 days in warm and moist conditions. You will see the tiny sprout coming out of the seed. Transplant into the soil, just under the surface. Gently pat the soil, or even just sprinkle it around the sprouting seed so you don’t damage the tender new plant.

Make sure the soil is nice and moist and kept in a warm place. I had a pet snake that I kept in a small bedroom at 80 degrees, and let me tell you, the tomatoes loved the warmth in that room. I germinate all my seeds in that room, and the warmth works like a charm.

Hydroponic Tomato Seed Germination

This method gives me nearly a 100% success rate and produces good strong plants. Hydroponic tomatoes seem to thrive for me from seed. I use a closed system that is kept at room temperature, even a little warmer, around 70 degrees Fahrenheit. I like to use rock wool cubes and a small paintbrush. The paintbrush has a thin handle that is rounded on the end and has a diameter of about 3/16”. I poke a hole in the rock wool cube, about ¼” deep or so, and drop a seed in the hole.  

Next, I place the cube in a mesh cage where I have a small stream of warm water spraying on it, keeping it wet. But because the seed is simply dropped into the hole in the now wet rock wool, it maintains enough airflow that it doesn’t rot. And the constant supply of fresh water and nutrients helps kick-start the new plant. My tomatoes did grow ridiculously fast in a hydroponic setup.  

Tomato Seedling Care 

Young tomatoes don’t need much, but they need what they need. I like to keep my young tomatoes in a heated room until they turn 8 inches tall. In a 75 – 80 degree Fahrenheit environment, this doesn’t take long at all. Tomatoes seem to thrive in warm conditions. That’s for sure, at least true with heirloom organic tomatoes. These are the varieties I prefer and have the most experience growing.

Seedlings also like things moist, but they like a fluctuation. I find that I water the seedlings heavily, then let them dry significantly, and again, I water heavily. This cycle seems to offer very good success for me in the warm environment where I grow the seedlings.  

Now, if you are going with hydroponics, there’s no such thing as too much water; just don’t drown your roots. They need to breathe in a moist environment, not drown in one.

Whether you are growing using soil or another substrate or growing hydroponic tomatoes, either way, you must remember about air movement. Air movement is vital for young tomatoes for two major reasons.

  1. Air movement prevents mold and fungus growth. This is always a concern in a moist environment. It is especially true if you are using soil that was not sanitized first.
  2. The air movement causes the plants to grow strong, thick stalks.  

Tip:  Use a small fan like that which you would use in a computer and make it blow on your young seedlings. You don’t want a tornado, but a ‘light breeze’ on the plants will do them a world of good and make them grow strong. A good fruit-bearing plant will need its strength to hold up lots of fruit remember.

Adult Tomato Plants

Depending on the breed of tomato you are going to grow, tomatoes can be a bit touchy, but I have found them to be quite hardy overall. That is, if you have grown the seedlings properly, they will grow strong for you. As previously mentioned, this includes growing seedlings under a light breeze to strengthen their stalks. 

One of the biggest problems I’ve had growing tomatoes is the stalks breaking under the weight and strain of carrying heavy fruit. This is why I felt it necessary to drill down on the stalk strengthening and its importance.

Adult tomatoes can cause a variety of diseases and issues, but I’m not going to get into potential ‘what-ifs’ in this article. As long as you keep things clean, don’t over-water, and tend to your plants regularly, you should have some great big monster tomato plants to contend with. But let’s talk about the soil for a minute if you aren’t going hydroponic.

Growing Tomatoes In Soil

Growing tomatoes in soil is the tried, tested, and true way of doing things. But making sure you are using the right soil is important to the healthy growth of your plants. Soil composition, pH, and water content are all important factors to consider when choosing a soil type for your plants. I go into a lot more depth in my soil types article, but to summarize, here’s what we want to look at:

Soil Composition

The soil composition is the recipe that makes up your soil mix. It might include such things as mulch, sand, dirt, peat, soil conditioners like vermiculite, and more. For our purposes, tomatoes generally prefer soil that is sandy loam or loam soil. Loam is a mixture of sand, silt, and clay. To make it soil, it must also contain micronutrients, and this is typically a fine mix of organic matter. But tomatoes will grow in just about any soil, so long as it isn’t compacted clay, which the roots have issues contending with.

The other consideration when it comes to soil is contamination. There are several forms of contamination I am concerned with when growing tomatoes. First, I want to make sure my soil has not been sprayed with any pesticides, herbicides, etc. After all, I want to eat the tomatoes I harvest without fear of poisons contaminating my food. This is why I truly believe that organic soil is the way to go when growing any food you intend to eat. For flower gardens and stuff like that, I’m not so concerned, but for my food, I want only the cleanest soils, free from man-made chemicals or additives, for that matter.


The soil pH is the next thing we want to consider. If you are using a decent organic mix soil, you won’t even need to bother worrying about pH. It is much more of a concern when talking about hydroponic tomatoes than it is when growing tomatoes in soil. As I mentioned earlier in this article, tomatoes are actually pretty hardy plants in my experience.

If you are going to check for pH, tomatoes prefer a neutral to slightly acidic soil pH. This would be somewhere between 6 and 7 on your meter. The meter I use, which I bought at Amazon for ten dollars, is this one. I like it because it’s cheap, works fine and also measures moisture. Obviously, it is of no use for hydroponics, but it works great for growing stuff in soil and measuring the soil pH and moisture. For the cost, I bought 2 in case I broke one of them.

Water Content

Water content is, naturally, an ongoing concern throughout the life of the plants. You don’t want to over-water the plants, but you don’t want them drying up either. The soil should be able to hold moisture. Again, as long as you are using decent organic soil, it works fine. I really like to add a little coconut husk to my soil. But don’t add too much, just a little, as this stuff acts like a sponge for water. I like the Coco Coir brand because it’s organic. And you get a huge brick for only $16.99.  I had a heck of a time finding coconut husk like this in stores. 

I found some little puck-shaped coconut husk products at one of my local gardening stores, but they wanted $20 for 5 tiny little pucks. There’s no way I’m wasting money like that, so again, I turned to Amazon for my solution. I’m not trying to sell Amazon here; I just found it way cheaper and more convenient than the local overpriced specialty stores.

Wherever you get it, I recommend coconut husk. It works great to help condition soil to hold moisture. Just don’t add too much, as it will make the soil ever so slightly more acidic as it slowly breaks down. But it takes a long time to break down, so don’t lose any sleep over it, either.

Growing Hydroponic Tomatoes

Materials I Used To Build My Hydroponic Tomato Setup

Lighting For Growing Hydroponic Tomatoes Indoors

Growing tomatoes indoors does require you to spend a bit of money on one part in particular:  The Lighting. This is not where you should ‘cheap out.’ The lighting is vitally essential to make sure your tomatoes grow strong and healthy. I use a multi-spectrum LED light with my indoor hydroponics setup. It works really great, but there is one downside: it gets hot. Now, this isn’t a problem if you have decent ventilation in the area that you have your setup.  

I found it actually saves me money because the lighting is helping to heat the room I use for my hydroponics and reptiles. That means my big heater turns on less, and I need to use the lights anyway, so it kind of saves me from having the big heater turn on and using more energy.

I’ve always been a big fan of variety. When we are relating this to lighting, I like to try to give my plants as much light as I can.  I don’t just use LED lighting; and I also use grow light spotlights directed right where I need them. This combination of lighting types seems to work really well for me.  

Overall, making sure you have as close to full spectrum lighting as possible will deliver the most benefits to your plants. Tomatoes will be happiest with a full spectrum, and this is delivered by grow lights, which emit higher color temperatures (4500-6500k). In my opinion, the higher, the better.

Fertilizing Hydroponic Tomatoes (And Soil Too!)

Tomatoes are hungry little plants. They need a lot of food. That being said, maintaining a decent food supply for your tomatoes is important whether you are growing in soil or hydroponically. The fertilizer you want should read 10-10-10 or even 10-15-10. If you really want to get into the science of soil, I recommend grabbing a decent soil testing kit like this one. That way, if your soil happens to be high in one of the primary nutrients, you can use a fertilizer that will compensate. But how do these numbers work with fertilizers?

The first number is nitrogen. The second is phosphate, and the third number is potash. These three numbers are always visible on fertilizer packaging as they are the national standard.  

Using soil that is organic and meets the earlier mentioned requirements for composition will likely not need a whole lot of fertilizing. However, I did notice in my gardens that the plants did much better following a small dose of fertilizer. I try to stay away from using chemicals in my gardens, but adding some fertilizer once every 2 weeks for the first 2 months of plant growth really enhances your plants.

If you have a fish tank, you could even use the fish water as a fertilizer; just make sure you dilute it so you don’t burn the plants.

Tomato Harvesting

What You’ll Need For A Great Tomato Harvest:

  1. Sharp scissors
  2. A basket or bag (trust me, if it goes well, you will have a lot to harvest) or Harvest Apron (my personal favorite).

And so the time has come to get some fruit. Here are a few tips for you. If you are growing outside, I recommend harvesting your tomatoes when they are still green and just starting to show signs of changing color. That is unless you have them protected from birds.

What I found in my garden this year was that I had some birds that would go and peck holes in my tomatoes as soon as they turned yellow and red. I also caught a squirrel mucking around with them as well. Remember, the bright red tomato is highly visible to all, so it tends to become a target. For that reason, I like to harvest just before they turn color.  

When you cut the tomato from the plant, don’t pull the green stalk free from the fruit. I like to cut the stalk about 1-2 inches back from the fruit. Keeping part of the stalk connected to the tomato helps the tomato ripen properly and also helps preserve the fruit longer, I have noticed.  

If you want your tomatoes to ripen ‘on-the-vine’, then you’ll want to pick up some chicken wire to cage your plants. I did this on some of my plants, and the result was fantastic. The critters were unable to access my plants, and I was able to harvest them later, allowing the tomatoes to ripen right on the plant.

Hydroponic Tomatoes Common Questions

How can I get more tomatoes per plant?

Use the sucker-pinch technique.  

This is a pruning technique where you pinch off the little suckers that grow off the existing joints where branches meet stalk. You’ll notice the tomato plants trying to grow new branches out of the joint where the existing branch meets the stalk. Pinch off these little suckers. If you don’t, the plant will put more of its energy into expanding its branch population and less energy into fruit production.

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