How to Grow Tomatoes from Seed

Learn how to grow tomatoes from seed and get our top tips for large, strong, healthy plants that will bear abundantly all summer long! 

Tomatoes are one of a homesteader’s favorite plants to grow in the garden! It’s no wonder when one plant is so prolific, heavily bearing one of the quintessential flavors of summer. Tomatoes seem to capture the very sun and express it in the flavor of their sweetly acidic flesh. If you’ve never had a ripe, garden-grown tomato you may not even really know what tomatoes tastes like. But if you have then you know they are worth every ounce of effort that goes into growing them. Growing tomatoes the whole process is a satisfying experience, delighting the senses.The pleasure of the experience aside, there are many reasons why you should consider growing your own tomatoes from seed. 

Reasons to Grow Tomatoes from Seed

Selection

There is such a wide range of varieties to choose from that the possibilities each year are almost mind-numbing. The rainbow of colors, red, orange, yellow, black, purple, even green; the range of sizes and purposes, grape, cherry, paste, slicer, beefsteak, heirloom, even storage; there are so many tomatoes to experience! Why settle for the same tired selection grown in the nurseries if you don’t have to?

My Favorite Tomato Varieties 

Every year I trial and grow a few new varieties of tomatoes from seed in my garden, but these are the ones I’ll always reserve a space for!

  • BrandywineThis variety is one of the most popular heirlooms for a reason! The perfect slicing tomato with a delicious, versatile flavor. Go with the true red one. I’ve found yellow & black Brandywine variations to be more susceptible to splitting in heavy rain.
  • PineappleAn heirloom yellow slicer with a red blush on the bottom of the fruit, these bad boys are huge and tasty!
  • Chocolate SprinklesThis is THE only cherry tomato I will never be without! Red & green stripes blending to almost a shade of brown these tomatoes have held up better in the last 2 rainy summers than any other variety. When every other tomato cracked or became so waterlogged as to have insipid flavor, Chocolate Sprinkles was still holding strong and maintaining their rich flavor which perfectly balances sweetness and acidity. Sungold cherry tomatoes are a close second but their flavor tastes purely sweet compared to Chocolate Sprinkles.
  • Principe BorgheseMy favorite heirloom cherry tomato with good flavor and resist splitting more than other varieties.
  • Golden TreasureAn interesting hybrid variety! These yellow tomatoes bear abundantly toward the end of the season. With yellow skinned exterior, red flesh beneath, they store well for weeks after frost. Imagine garden-fresh tomatoes with your Thanksgiving dinner!

Organics

One of the benefits of growing your own tomatoes is that you will know just how they were raised from seed to table. If organic vegetables are important to you, this is a worthy step. Moreover, when nursery plants become dependent on chemical supplements for health, it’s a double shock to their system when its for transplant and they lose the support they had grown accustomed to. Your tomatoes will be hardier and healthier if grown from seed at home. 

Save Money

Don’t get me wrong, a pack of tomato seeds isn’t as cheap as it used to be, however $5 for 25 potential tomato plants is a thriftier choice than buying those same 25 plants from a nursery. If you don’t need 25 plants, and most folks don’t (or if they did wouldn’t dream of growing all of one variety) tomato seeds will still be viable for a couple of years. (I comfortably plan on getting 2-3 seasons from a pack of seeds. After that I buy an extra pack for a little insurance in case the germination rate is too low in the old seeds.) 

Extended Season

Many of us spend all winter eagerly anticipating the warm day when we can break the soil and tuck our seeds (or seedlings) beneath. Growing tomatoes from seed will allow you to kick start the gardening season and get your hands in the soil months earlier.

Self-Sufficiency

It’s important to know how to grow your own tomatoes from seed in the event that, for whatever reason,  you’re not able to find tomato plants available one day. Likewise, it’s also important to grow an heirloom variety or two and know how to save their seed. I love some of the hybrid tomato varieties available these days! They are often more flavorful, disease tolerant, resist the influences of weather, and more productive. However, I’ll never be without a few tried and true heirloom varieties that I can count on saving seed and propagating each year without additional inputs from seed catalogs or nurseries. 

Tomatoes Grown from Seed

How to Grow Tomatoes from Seed

Tomatoes are very simple to start from seed. Their quick & easy germination is rewarding and you don’t need to wonder if your seed was bad or you did something wrong. You’ll know within a few days. That said, tomatoes, grown well, require quite a bit of attention compared to other indoor seedlings. You may get to the end of this article and think that’s way too much work! It is a bit tedious. But this extra TLC will mean the difference between tall, leggy, tangled, drooping, pale plants and vibrant, strong, sturdy, healthy ones. They’re worth the work and will reward you one day with pounds and pounds of brilliant crimson flesh. 


Want to get a quick peek at my tomato growing system? Head on over to @quill_haven on Instagram and check out the Tomatoes from Seed highlight for a quick explanation of how I start tomato seeds indoors.


Supplies for Growing Tomatoes from Seed

There are several supplies you’ll need to grow your own tomatoes. The biggest requirement being: Space. These guys will take up quite a bit of room by the time they’re ready to hit the garden so bear that in mind. 

Other supplies you’ll need: 

  • Potting soil, I prefer a light potting soil without a lot of wood chunks
  • Blood meal, or feather meal, bone meal
  • Vermiculite, Prevents damping off disease
  • Grow lights, I use one warm bulb & one cool bulb
  • Soil blocker, or 1x” cell packs
  • Seedling trays, with and without holes
  • Solo Cups, for transplanting
  • Fish emulsion fertilizer
  • Oscillating fan, optional

We’ll cover more about these supplies in each section below. 

When to Plant Tomato Seeds

For big, beautiful, resilient plants you will want to start your tomatoes about 8-10 weeks before your last frost date. This timeframe does allow for some wiggle room, especially if you have unpredictable spring weather. If your extended forecast looks promising and your soil is warm you’ll be able to plant these guys early. They’ll be ready. It also allows for mistakes. If your seeds didn’t germinate, you lost the seedlings to damping off disease, or your cat decided to take a nap in the tray, you’ll have time for a do-over. 

Pre-Sprout Tomato Seeds

Pre-sprouting seeds is a process commonly called “chitting.” The purpose of chitting tomato seed is to be sure that you aren’t planting unviable seeds. This is more important if you will be planting last year’s seeds which may have lost some viability. 

To chit tomatoes from seed, write the variety name on a plastic bag. Soak 2 paper towels and wring them out so they aren’t dripping but are still saturated. Singly arrange your seeds on 1 paper towel and cover them with the second. Slip the paper towels in the gallon bag, seal it, and set it in a warm place (light isn’t necessary for germination of tomatoes.) If your paper towels dry out at any point, spray them with water to add moisture.

After about 3 days you’ll notice each seed has put out a root (radicle). Those seeds are good, you can plant them! 

You can wait another day or so before planting without harm but if the radicle gets too long it may pierce through the paper towel and run the risk of getting torn off when you remove it which means that seed is no longer plantable. So I plant the seeds twice to make sure that doesn’t happen. I’ll do the first planting the second day after noticing radicles emerge and the second one a couple days later. Any seeds that may germinate after that point will not make as hardy & productive a plant. It’s time to let them go. 

Tomato Seedlings

How to Plant Tomatoes from Seed

Set up your growing station and lights where you can easily attend to them and it isn’t too chilly. Tomatoes are heat-loving plants and they won’t do as well in a 50F basement without supplemental heat. That said, too warm and you risk growing tomatoes that are leggy with weak stems. We’re looking for growth on the slow side, building strong, resilient cell walls. The 60F range has worked really well for me.

Tomatoes are nutrient hogs. They are heavy feeders and require quite a bit of supplementation throughout the growing season to reach their full potential. To give them the best start possible I mix in a handful or two of blood meal in with my potting soil so there is extra nitrogen right already there when they need it. 

Fill your cells or create soil blocks. You will want to start with fairly wet potting soil before making pots. If you begin with wet soil (or let it dry out later) it is challenging to get it moist again. 

I use a 1” soil block to start tomatoes from seed, saving on pot costs over time, and pot them up later once they’re well on their way. This saves me a ton of space in the basement for as long as possible so I can start more seeds without wasting it on tomatoes that might not even germinate. Cell packs can be used but I like not having the waste or storing them if they didn’t fall apart by the end of the season. 

The soil blocks or filled cell packs get set into a cell tray with holes that is resting in a cell tray without holes. This system allows for under watering your plants which provides a more constant water supply to the tomatoes, allowing them to take up what they need. 

If you didn’t chit your seeds, plant just 1 tomato seed per cell so there will be no need to thin them later. Since we will be potting them up in a few weeks we can sacrifice the potential space to an ungerminated cell. With tomato seeds typically coming 25 to a pack, doubling up would mean each pack only contains 12 or so future tomatoes for your garden. Every seedling you thin could have been next year’s tomatoes. 

Sprinkle a light layer of vermiculite over the soil. Seedlings are susceptible to soil-borne disease, especially damping off disease, which is characterized by the stem weakening and shriveling just above the soil then falling over like a felled tree and dying. Vermiculite provides a bit of a barrier and has nearly fully reduced damping off disease in my seedlings since I began using it.  

Keep your soil moist (consider covering it with plastic) and warm for the next 3-4 days. Light isn’t necessary at this point. Tomato seedlings will germinate without it. Just be sure to keep your eye on them so you can transfer them to your light station after they germinate. 

Caring for Tomato Seedlings

At first tomato seedlings need very little care. Their needs are simple: Light & water. 

Light

Tomatoes seedlings do well with 14 hours of light. Use a timer to make sure you don’t forget to turn them on or off. Keep the light just a few inches above the tray, raising it as the plants grow and come close to touching the bulbs. If your light is too far above the plants they will “reach” for it and their stems will be thin and weak. 

Water

As mentioned earlier, I prefer to under-water beneath the holed tray, into the tray without holes. I try to leave 1/2” of water in there for the plants to use as necessary & to keep the soil moist. (It will wick it up.) Once the tomatoes grow larger they will consume water at a faster rate and I’ll fill the tray about halfway with water so I don’t have to water every day.

Potting Up Tomatoes Seedlings

Once your tomato plants have outgrown their home, their stems are 6” or taller, and they are packed into the flat, it’s time to pot them up! 

I use red solo cups to pot up tomatoes because they are inexpensive, sturdy enough, and have taller sidewalls. We’re about to bury those tomatoes to all but the top few leaves.

Stab a few holes in the bottom of each cup so we can continue under-watering. (I stab holes in all the cups in the pack so there’s no risk of kids stealing them and playing with them over the next year.)

Mix up another big batch of potting soil and blood meal. Put about an inch of soil in the bottom of each cup. Carefully transfer the seedling to the cup and bury it all the way to the top two leaves. If the plant is below the rim of the cup, that’s ok, it will grow up soon enough. As it does, simply add more moist potting soil to bury it. If the plant is taller than the cup, that’s ok too, just bury what is there. 

Your tomato will grow more roots all along the length of the buried stem making for a stronger root system and more ability to take up nutrients and water to feed the plant! 

Now you will only need a solid no-holed tray to place your cups. Set them up under the light and then place the cups in the trays there. (Don’t set the cups in the trays and then try to transfer them. It’s quite the balancing act and you risk tumbling cups and snapped stems or leaves.)  

Avoid having the leaves touch each other in the tray, if at all possible. Tomatoes like to keep up with the Joneses. They are sensitive and touching leaves will trigger a burst of growth in an attempt to outcompete their neighbor. 

Once again, these little things are all about avoiding leggy stems and tall plants that won’t have the strength to hold up their own heads later. 

Continue raising the light as the tomatoes grow and keep water in the tray. Watering is much easier now because you don’t have to water between trays, just pour it right into the no-hole flat tray and fill it up. The plants will take what they need! At this point, I probably only fill the trays with water once a week. So long as the soil doesn’t completely dry out it’s ok if they don’t have a constant supply of water, something they will probably be experiencing in the garden and will make them hardier & prepared for the inconsistent environment of the outdoors. 

If you’d like to be sure your stems are as strong as they can be you can put an oscillating fan on them for an hour or so a day to strengthen the cell walls. 

How to Grow Tomatoes from Seed

Fertilizing Tomato Seedlings

As mentioned, tomatoes are nutrient hogs. They gobble up nitrogen to make all of that green vegetation. The young tomato plants will probably need fertilizer at some point in their growth before transplanting. You can do this prophylactically or when you notice the leaves beginning to turn yellow, indicating nitrogen deficiency. If you choose to do it prophylactically, before there is a nitrogen problem, choose a time about halfway between potting up the seedlings and transplanting. 

My favorite choice for this is fish emulsion fertilizer. Choose a warm day if possible so you can open the windows and don’t invite guests over because, as you might imagine, fish emulsion stinks. But once it dries, the odor goes away. I add it to the underwater tray and mist the leaves at the ratio indicated on the product. 

I will also give my tomato plants a boost of beneficial bacteria by misting them with raw milk. Soil critters are the nutrient supply chain of the vegetable garden and I want to get them up and running before the plant even hits the garden. 

Hardening Off Plants of Tomatoes from Seed

About 7-10 days before transplanting, begin hardening off the tomato plants. This process acclimates the plants to the sun, wind, and fluctuating temperatures. If you’ve been using an oscillating fan you’ve got a jump start on the process because your plants will be used to a breeze. Still, don’t choose a windy day with clear blue skies to start. A calm, overcast day works best at first to prevent sunscald on the leaves. Set your tomatoes out for a few hours in the morning and then bring them back inside. Each day, leave them outside a few hours longer until the last couple of days they can stay outside overnight without bringing them back in. 

Transplanting Tomato Plants

If your tomatoes have adjusted to being outside and are still doing well, the chance of frost has passed (or the forecast looks promising & you have a way to provide frost protection if the weatherman lied), it’s time to transplant!

Remember how we buried the tomatoes up to their top leaves during potting up so the root system would be strong? We’re going to do that again! 

You may not be able to dig down as far as you need to and that’s ok- you can dig at a trench at an angle and lay the tomato lengthwise in it. Just be sure not to bend the stem as it comes out of the ground at too sharp an angle. It will straighten up in the next day as it starts to reach for the sun. 

Once again, you can sprinkle a little bone or blood meal into the soil with the plant so you don’t need to spray fertilizer so soon which gives you a chance to move on to tending to other garden tasks during the spring planting rush. 

Now is also a great time to lay down mulch around your plants. Tomatoes are often susceptible to soil-borne disease and the mulch will prevent soil from splashing on the leaves during a hard rain (as well as add organic matter to the soil, surpress weeds, and help retain moisture in a dry spell.) I do not recommend using wood chip mulch for tomatoes since their nitrogen needs are so high. Wood chips too easily get mixed in with the soil and when they try to break down will tie up the nitrogen, robbing it from your tomatoes. Grass clippings, organic straw, or old hay work best. 

Green Tomatoes on plant

Trellising Tomato Plants

There are many ways to trellis tomatoes and which you choose will depend on your garden space and what works best for you. I grow tomatoes in a 50’ long bed that is 3’ wide so the Florida weave trellis is my favorite way to keep them contained. 

Whichever method you choose, I highly, highly recommend putting the system in place NOW. It is so much easier to set your trellis up while the plants are small instead of waiting until they are overgrown and out of control. 

Fertilizing Tomato Plants

Unfortunately, the nutritional needs of tomatoes don’t stop once they hit the garden, though if you have an active soil microbe population and strong root system your plants will be able to more easily mine nutrients from the earth. 

I continue fertilizing my tomatoes every 2-3 weeks with fish emulsion until they begin fruiting at which point their nutrient requirements shift from nitrogen-based vegetative growth to calcium-based fruit production. Now I use raw milk as fertilizer. It can also be sprayed in the garden soil and on the plants to nourish them and the soil life. 

Pruning Tomato Plants 

Many folks recommend aggressive pruning of tomato plants to put the focus of the plant’s energy into fruit production instead of shoot production. In theory, this makes sense but it depends on what your objectives are in the garden. I’m not concerned with the largest, market-quality fruit. I have a family to feed and want to do so in the least space, with the least effort possible. (This may seem laughable after reading through all of the efforts that went into growing tomatoes, but while you may be able to direct seed, set & forget lettuce the yield, preservation capacity, and calories that come from the easy harvest don’t even compare.)

However, I am concerned with making sure there is plenty of airflow and sunlight among my tomatoes in order to prevent leaf and fruit diseases that stem from rainy weather where the leaves don’t dry out quickly. 

So my recommendation is to prune modestly. After the plant is a couple of feet high, begin removing the lower branches closest to the soil to prevent soil-borne diseases. You can also prune off any unruly branches that make moving in your garden difficult. Just don’t prune off the top leader.

Lastly, you can remove the suckers from the tomato plant, if you choose. It’s more important for indeterminate plants that will continue vining and growing throughout the season. 

I snap them off while the plant is young and they’re easy to find but once it really takes off I don’t worry about it as much, knowing that those later off-shoots will be bearing fruit for me in October when the rest of the main plant is done. 

You can easily identify the sucker because it will grow out of the wide-V crook between the main stem and a branch. The branch will look older and stronger, while the sucker is often just a couple of leaves in the crook (when young) or a tender-looking stem (when older.)

Hornworm with Parasitic Wasp Eggs

Tomato Pests

The pests that can affect tomatoes are wide and varied depending on where you live. I could research that information and pretend like I know what I’m talking about when I’ve never even seen a whitefly in my life. But I despise sharing knowledge I’ve no experience with. 

In my garden, in central Ohio, tomato hornworms are the primary pest I deal with, and occasionally stink bugs will suck at the fruit, leaving unsightly marks which open up the way for disease. 

I take a passive approach to hornworms and, unless they are out of control, leave them on the plant. Most likely, I’ll find them in a few days with little white eggs sticking up from their back. At this point, the worm is paralyzed and can do no further damage to the tomato. The eggs, those of a parasitic wasp, will hatch and help fight any further attacks from the hornworm. In each of my gardens, I’ve had one initial fight with the worms where I had to thin out the population to mitigate damage, and every year since then the wasps have kept it well underhand. 

The simple solution to stink bugs on your fruit is to grow a trap crop of produce they like better than tomatoes, such as cucumbers or squash. (Unfortunately, I can offer no advice on dealing with them other than hand-picking or the duct tape solution.) Same with flea beetles. Though I’ve never had a problem with flea beetles on my tomatoes, I have had problems with flea beetles. A trap crop of eggplant, arugula, or potatoes will keep them away from your tomatoes. 

For more information about dealing with various tomato pests see HERE.

Tomato Diseases

Likewise, since I started growing my own seedlingsI haven’t dealt with tomato diseases in the garden to speak with much experience. I believe this is because I put so much care into providing the hungry plants with the nutrients they need to grow well. 

My biggest challenge, which is not necessarily disease-related, stems from an overly wet summer, something entirely out of my control. In a very wet summer, the fruit swells, splits and may rot before fully ripening. If there is an expected period of heavy rain I will harvest unripe fruit just before the storms begin and bring them inside to finish ripening later on a sunny windowsill. 

You will find a great deal of information about tomato diseases HERE. As you skim it over, notice that many of the tasks outlined above, such as mulching, trimming the bottom branches and thinning the plants for airflow and sunlight to prevent the leaves from holding too much shade and moisture would have prevented most of these diseases. Proper nutrient supply would have taken care of the rest. 

Harvesting Tomatoes

The next step in growing your own tomatoes is, hands down, the best- the harvest! Just when you thought the work was done, I’m here to dispel your disillusions. The entire purpose of the tomato plant, from it’s view and yours, has come down to this moment. How you take advantage of it will make all the difference in the yield you harvest.

Tomato plants must be continually harvested if they are to keep bearing until frost snuffs out their life.

If you get busy and allow too many tomatoes to rot on the vine and drop their seed, the plant believes it has fulfilled this mission on earth and will not produce new tomatoes. Your growing season is over.

I always drove around my rural community and wondered how I was able to get tomatoes straight up to frost and when my neighbors were pulling their plants from the ground a month or earlier. Then one summer, while building a house, I put my kids in charge of the harvest. Their, “Yeah, Mom, we got all the tomatoes” cut my harvest short by weeks and I soon realized why.

So even if you don’t have time to process the tomatoes, be sure to go out and pick them for the chickens or pigs so when you’re ready to jump back into making all the sauce, salsa, chutneys, paste, and more you have fresh tomatoes clinging to the vine!

How to Grow Tomatoes from Seed :: Get tips for growing strong, healthy tomato plants in your organic garden!

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