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How to Plant Tomato Seeds: the Absolute Best Method

Tomato plants are considered by many to be the pinnacle of gardening, and even a rite of passage for all types of gardeners. Beloved by gardeners and non-gardeners alike, it’s hard not to consider tomatoes the perfect vegetable to grow: it’s easy, and the rewards are delicious! You can grow tomato plants either by buying young tomato plants at your local nursery and transplanting them into your garden, or directly planting the tomato seeds yourself.

How to Plant Tomato Seeds

Here we’ll be learning all about how to plant tomato seeds-starting with the many reasons why gardeners would want to start from seeds!

Why Start Tomato Plants from Seeds

At first thought, you might think that buying tomato transplants for your garden is the most convenient way to grow tomatoes. While that might be indeed true, there are many benefits to learning how to plant tomato seeds yourself.

To begin with, seeds are simply cheaper than young plants. So you’ll be saving money by doing the work yourself, and have a bigger budget for other gardening needs later on.

Secondly, and perhaps more excitingly, is the fact that if you’re buying transplants at a nursery, you’re limited to the plants sold by said nursery. Typically, there is much more variety in the seeds they sell (and even those available online!), meaning you can grow less common and more unique tomatoes by learning how to plant tomato seeds yourself!

Choosing the Best Tomato Seeds

Now that you’ve firmly decided to learn how to plant tomato seeds, the next step is choosing the right kind. There are hundreds of tomato varieties out there, so it’s important that you select the one that best fits your needs, expectations, and available resources.

When learning how to plant your tomato seeds, start with a simple question: how will you want to eat your tomatoes? Layered in a burger? Small and juicy in your salad? Sliced atop a bruschetta? Perfect for pasta sauce? As you probably might guess, some tomatoes are better suited for different types of consumptions than other.

Choosing the best tomato seeds

Another factor to consider when learning how to plant tomato seeds is the kind of space you have available for your tomato plants. Determinate tomatoes grow around three feet at most, and are a good choice if you wish to grow them in pots (keep in mind that you’ll still need a container of about 10 gallons). Indeterminate tomatoes, though, can grow very, very tall, and most likely need serious support like tomato cages or ladders. That’s probably not something you’re equipped to sustain on a small deck!

Something else you could think about is whether you would like to grow heirloom tomatoes. Heirloom seeds are collected and passed down through generations of plants, which means they have not been recently crossbred. It is believed that for this reason, heirloom tomatoes usually taste better, and have more health benefits. Who knew learning how to plant tomato seeds could even be good for your health?

Additionally, you should choose a tomato variety that is disease resistant to avoid working hard to grow your plant, just to lose it to disease. And, no matter what variety you choose, experts advise you go with the organic option, which are also better for your health and usually taste better, too!

How to Plant Tomato Seeds

Materials

Learning how to plant tomato seeds takes some planning, so it’s best to start with a list of materials you’ll need:

When to Start Planting Tomato Seeds

When it comes to learning how to plant tomato seeds, one important factor to consider is that tomato plants have a long season, and thrive in warmth and sunlight. So experts tend to agree that it is best to start seeds indoors before the last frost to get a head start, and only transplant them into the garden when the weather has warmed up for good. This gives them the greatest chance of not just survival, but a healthy growth and plentiful output of fruit.

When to start planting tomato seeds

To this end, you should plant your seeds four to six weeks before the average last frost date of the winter. This gives your tomato plants enough time to germinate and be ready to make tomatoes as soon as the warm weather hits!

If, however, you’re planning to grow your tomatoes in pots permanently indoors, then you can plant them anytime without having to worry about the climate outdoors.

Containers

The next step in learning how to plant tomato seeds is picking a container for them! You have many different options at your disposal. You can buy trays made for growing plants from seed, which are usually either plastic or biodegradable. But in reality, you can start your seeds in virtually any clean container that has good drainage-if the soil becomes soggy, this could rot the tomatoes roots, and expose them to diseases.

That means you can use egg cartons, paper cups, and even yogurt containers as long as you poke drainage holes at the bottom, and place them in waterproof bowls or plates to collect the drainage. Don’t, however, choose a container that is obviously too big for a young plant-you might not think it makes a difference, but this makes it easy for the extra soil to stay too wet and damage the plant! This runs the risk of setting you back in your journey to learn how to plant tomato seeds.

Soil

Now that you’ve selected the perfect container, the next thing to consider when learning how to plant tomato seeds is the kind of soil to use. Some gardeners actually suggest not using soil at all, and instead using a soilless starting mix. What you certainly shouldn’t do is use soil from your garden, which is probably too compact and could contain harmful organisms or diseases which might infect your tomato plants.

Using the best tomato plant soil

Whether you go for potting soil or soilless mix, make sure it is high quality, sterile, and specifically made for seed starting.

Planting Your Seeds

On to the fun part! As mentioned earlier, the best idea is to start your seeds in containers indoors to get a head start on the season and ensure a healthy growth. Here are the steps you should follow when learning how to plant tomato seeds:

  1. Put two or three seeds in each container, leaving space among them.
  2. Cover them in a thin layer of soil (or the soilless mix!). It should be so thin that it almost feels like you’re sprinkling it on top of the seeds!
  3. Pat the surface of the soil to make it firm, but don’t press down on it too much.
  4. Use the spray bottle to water your seeds, but make sure not to soak them-some say just four to five squirts should give your seeds a sufficient amount of water to start with. Others say that the soil should have the same moisture feel as a wrung-out sponge!
  5. Cover your containers loosely with a plastic wrap to help maintain the moisture.
  6. Wondering why I listed popsicles in the materials section earlier on? Now is the time to whip them out: label them with the date and tomato variety (the latter is especially important if you’re growing more than one tomato plant variety at once) and stick them into your container (you’ll have to pierce the plastic wrap).
  7. Your seeds won’t need light right away, but they will need warmth. Place them in a dark location with a temperature between 70 and 80 degrees Fahrenheit. If you don’t have any location at this temperature, use a heating mat to keep them warm.

Your tomato seeds should germinate within one to two weeks! Then comes the part that most gardeners find the hardest, but not because of how tricky it is.

When it comes to how to plant to tomato seeds the best way, in order to ensure strong and healthy plants, you really should only grow one seedling (very young plant grown from seed) per container.

Hold on, you must be thinking, didn’t you tell me to plant two to three seeds in each container in step one?

The answer is yes, and that’s to mitigate the possibility of one or more of the seeds in each cell not growing. Sometimes, however, every single seed you planted germinates, at which point you should do what is called thinning: getting rid of all but one seedling in each pot. This might feel heartbreaking, but it’s an important step!

If you really really don’t want to discharge any of your seeds, you can always remove the extra ones and transplant them into different containers. Remember, though, to keep in mind the space available to you. You wouldn’t want to end up with more tomato plants than those you can keep!

Once the plants germinate, move them to a slightly bigger container to make room for their growth before you ultimately transplant them into their final container.

Water

You should continue watering your seedlings with the spray bottle until they’ve germinated, at which point you can convert to a traditional watering can. As mentioned earlier, keep the soil moist (during germination as well), but avoid sogginess at all costs.

Watering tomato seeds

When watering, you should also be careful to pour the water directly into the soil, and not let it dampen the actual plant too much, which could cause damage. This is an easy mistake made by amateur gardeners learning how to plant tomato seeds!

Warmth and Light

Once your seeds have germinated, you can remove them from whatever dark corner you have been keeping them in. They are now strong enough to thrive at slightly lower temperatures (around 65 degrees Fahrenheit).

Needless to say, however, tomatoes remain warmth-loving plants, so their next home should be near a very sunny window, or beneath a growth light. Some gardeners believe that growing lights are preferable to even the sunniest of windows. This is because growing lights can be placed very close to the soil (just a little above the seedlings), which allows the seedlings to grow thick, solid, and straight up (the way they would if they were growing outside!).

If you use growing lights, remember to raise them as the plant continues to grow!

Tomato growing light

Plants that grow next to windows usually end up being “leggy,” meaning long, thin, and usually more breakable. The one-sided light source also encourages plants to grow crooked. The good news, though, is that the crookedness is easily preventable-just make sure to rotate the container a little bit every day to distribute the sun exposure to all sides of the plant. There’s a sneaky little tip for how to plant tomato seeds successfully for you!

Feeding

When learning how to plant tomato seeds, it’s important to keep in mind that tomatoes should be well fed. It’s especially important that they receive vital nutrients during their first two weeks. Use liquid fertilizer, worm casting, or compost tea, and start the feeding routine about a month after planting the seeds.

Prepare Your Tomatoes for the Outdoors

Congratulations! Now you’ve got yourself some young and healthy tomato plants on your hands. If you plan on keeping them permanently indoors, then all there is left to do is eventually transfer them into their final, bigger container. If you want to transfer them outdoors, though, there’s still a couple of simple steps left.

Before you can transfer your tomato plants outdoors, it is crucial to harden them off. What does that mean? Hardening off plants means preparing them for the likely harsher outdoor conditions by slowly introducing them to the new environment, a little bit at a time. This is an important step in successfully learning how to plant tomato seeds. If you don’t do this, plants might go into shock, and even die.

It might sound complicated, but it’s actually pretty easy. The preparation can begin really early, when the tomato plants have just germinated. Gently brush your fingers through their little leaves once a day: this simulates wind, which triggers the plants to grow stronger in order to avoid wind damage. Pretty cool, right?

Touching a tomato plant

Once the plants are a little older (about four to six weeks old) and you start thinking about putting them outside, start with three or four hours a day in a sheltered area of your outdoors. The temperature should never dip below 50 degrees Fahrenheit-if it does, that means it’s still too early in the season!

Do this for 10 days to two weeks, and then start leaving them out longer and longer each day. Within eight weeks or sooner, your tomato plants will have acclimated enough to transfer or transplant them permanently outside. Congratulations!

Growing tomato plants

Continue keeping an eye on the weather, especially how chilly it gets at night. If there’s ever a risk of a random cold night, cover or wrap your plants to protect them from the cold, if you can’t bring them back inside anymore.

Now You’ve Learned How to Plant Tomato Seeds!

Now that you’ve learned how to plant tomato seeds, there’s no holding you back! Think of all the amazing recipes that call for different types of tomatoes-and you don’t even have to limit yourself to the transplants sold at your local nursery! Interested in more tomato content? Check out our tomato blog on our website for more growing guides!