Growing Tomato Plants from Seed
Growing plants from seed can be a very rewarding and fun experience when you start with just a few, basic know-how’s. I have seeded everything from broccoli, peppers, and watermelon, to beans and much more. And, of course, lots of tomatoes! In this post I will use pictures to show you what to do to plant tomato seeds, how to care for the tiny seedlings, and also how to transplant them when the time is right.
The first time I seeded anything at all, more than a decade ago, was a complete flop. Since then, I have learned just how easy it can be and have grown to really love seeding my own plants. My absolute biggest mistake in the very beginning was to put the newly seeded trays away from where I could see them, in order to also keep them away from my cute little toddlers. The problem was that since I didn’t see them, I forgot about them (the trays, not my toddlers! Ha!) and didn’t water the seedlings often enough. When I did water, I didn’t realize just how fragile these tiny plants were, and knocked them over while watering from a watering can that was far too forceful for them. The poor little plants didn’t stand a chance and quickly gave up. And so did I. I did not believe I had it in me to grow anything from seed!
It took years before I decided to try again, this time to find that I do, indeed, have it in me! And most likely, so do you! Now that I keep my sprouting little seedlings where I see them daily, and tend to them carefully, I have grown countless tomato sprouts into huge, beautiful, lush plants, many of which were transplanted into my own garden, and still more that I have had the pleasure of sharing with others.
Which type of tomato you will want, and how large you prefer the tomatoes to be, will of course be one of the first things to think about. However, there are some other things to keep in mind as well, when selecting seeds:
Some plants are determinate, others are indeterminate. Indeterminate plants will continue to grow and produce fruit all season long until the plants die from hard frost in the fall. If they are in ground and conditions are right, some will grow to be 8 feet tall or more, requiring heavy staking, unless you want it sprawling on the ground catching diseases and not get enough sun for a good harvest. A grape tomato plant that I gave to my father-in-law grew high up into a nearby tree! When in pots though, they will not necessarily grow much beyond 4-5 feet.
Sometimes determinate plants can be more manageable as they grow to a certain size and then stop. They usually do not require staking as they will stay more compact, perfect for a patio. However, they will grow only one crop of tomatoes that will all ripen at about the same time, great for canning season but not if you want tomatoes all summer long. I have grown both determinate and indeterminate plants on my deck and in ground without a problem. I would not let size be the determining factor (no pun intended) when choosing seeds or plants unless space was a true problem.
Hybrid vs. Heirloom:
Most tomato plants and seeds available at stores and nurseries these days (as well as supermarket tomatoes) are hybrid varieties, which means they have been specially grown and bred to create disease resistant and hardy plants and fruit. Flavor is often sacrificed, though there is still no comparison between a homegrown tomato and one from the store! Fruit that has been allowed to slowly ripen on the vine is so much worth the effort it takes in caring for the plants.
Heirloom tomatoes, which have been reproduced for several generations, are often more flavorful, but these plants are prone to disease and harder to care for. Seeds from heirloom tomatoes can be kept and seeded the following spring and the new plant’s fruit will stay true to its original tomato. Seeds from hybrid plants will grow if they are planted, but you cannot know what type of tomatoes you’ll end up with because of cross pollination. This means your original disease resistant hybrid plant can produce seeds that will result in diseased plants. Therefore, seeds from hybrid tomatoes should not be used.
How many seeds to purchase and plant?
I usually seed for a lot more plants than I want to keep. Personally I want to start out with at least three times as many plants as the number I actually want to keep, and sometimes I start with two seeds in each cup with the plan to weed out one of them. *More information on this below. By seeding extras, I can select from and keep the strongest ones, toss the weak ones, and share the rest of the good plants with friends and family. But I do often end up with a forest to care for, for a little while!
When and How to Plant Tomato Seeds
Most tomato varieties should be planted 6-8 weeks before the last expected day of frost for your area. For me, in zone 5, that means Memorial Day or end of May. I like to give them ample time, so I plant around March 20th or so.
Personally I find egg cartons to be the perfect starter home for tomato seeds. I put down the date of seeding directly on the “tray”, and sometimes, if I seed different plants in the same tray, I will number each cup and keep track of the different plants in a notebook.
Fill the egg carton trays with potting mix, placing the seeds on top, then covering with more soil. How much to cover with depends on the seeds you are using. You will see this information on the seed packets, and I use this info as approximate debts. You can also fill the cups first, then make little holes for the seeds, stick them in and brush the soil over. Whatever you find easier.
It is best to use a bagged potting mix rather than soil from outside, as potting mix is lighter on tender roots, and clean. Soil from outside tends to pack too much and can carry disease and contaminants that you won’t want in your house or spread to the gardens of people you share plants with. (I will refer to the potting mix as soil in this post, just to clarify.)
*In the following picture (very blurry, unfortunately), you can see some little yellow dots on top of the soil, two in each cup. These are the seeds. I put two or three seeds in each cup and later remove the weakest plants to allow for one in each cup. Some seeds might not sprout at all, especially if they are from previous seasons, so it helps to guarantee you one good plant in each.
For these seeds, I covered with approximately 1/4 inch of potting mix. If you use seeds from your own heirloom plants, a general rule is to cover with soil as deep as the length of the seed; if the seed is 1/4 inch long, cover with 1/4 inch soil. Gently water with a sprayer so that the water flow will not disturb the seeds or cause them to shift. This is a fun job for kids, and my 10 year old son does a great job as you can see on the next picture. I generally have him do two sprays per cup, checking to see how that works out. You’ll want the soil to be damp, not soaked. Holes on the bottom of the cups should not be necessary at this stage with careful misting of water.
Before sprouting, seeds do not require light, but warmth is important. After the sprouts emerge, they should be placed in an area where they receive a lot of light, and temperatures of at least 65 degrees. As they begin forming a lot of leaves, they will require direct sun most of the day. Tomato plants love full sun and warm weather, and will not produce properly without it. I have found my plants to struggle more with disease in years when we have had a lot of rain and overcast.
And make sure you have someone to guard the trays at all times! My guard’s name is Jasmine, or Jazzie for short. You can just tell how she’s scanning the area for potential threats! She’s looking out for us, just like always. Yeah.
To make a tiny, miniature greenhouse, I cover with plastic foil and poke a few holes in it to allow for air circulation. The plastic will help warm up the soil just a tad, and will also help retain moisture to prevent the plants from drying out. I do check on the plants every day, and mist with water whenever needed. Remember: moist, but not wet.
If it should accidentally happen that the soil gets overly wet, you can gently put some paper towel loosely on top of the soil to absorb as much as possible, and remove the plastic until the excess water has evaporated. The soil will pack together when this happens, so it is not an ideal situation. A sprayer will be very helpful in preventing an accidental over-watering.
And here’s the very first little babe!! A little girl! OK, maybe not… But this is getting very exciting! I usually check several times a day at this point, just because I find it so fascinating! These seeds mostly sprouted on day 5 and 6, but this can vary by several days. I had one sprout as late as day 16 this time around.
In the next couple of days, as the tiny sprouts start to grow taller, I often stick down blunt-end toothpicks or similar, in the soil to help hold the plastic up and away from the plants. Otherwise they will not have the room they need to grow. This is now day 7, so it’s only a day or two after sprouting. Some are still working on developing their seed leaves.
Spacing the Plants
The time has come to start spacing the seedlings, to allow for plenty of room for individual plants to grow. Select the strongest plants to stay, and snip away the rest. I keep the ones that look the healthiest, thickest around the stem, and generally have come the furthest. I just snipped off the one I’m pointing to here, …
…and will remove this one too since it’s growing too close to a different one:
Don’t just yank them out, but snip them off gently so you don’t disturb the roots of other plants growing nearby. You can use your finger nails as well; just cut them off. The remaining stem and tiny root system will wither, so you can leave them alone. In another few days I will remove more plants until I have only one per cup remaining.
In this next picture, you can see the beginning of the next set of leaves, which is the first set of true leaves. They started emerging on day 10. As these true leaves develop, you will eventually see the seed leaves, the original first set of leaves, wither and drop. This is no reason for concern. In fact, you should expect this to happen, as the tiny sprout now has used up the nutrition found in these leaves, which was used to sustain the plant in the beginning.
I am now down to one plant per cup, and they are strong enough to handle watering from a bottle rather than the sprayer. This is faster and easier, and I have found a regular drinking bottle with a top on to work very well. I just give each cup a few dribbles and move on to the next. I have basil growing in the front left cups. Tomatoes and basil thrive very well together and can be grown side-by-side in the garden.
When the plants are about 2-4 inches tall with at least one set of true leaves, they should be transplanted to a cup or pot of larger size than the tiny egg carton cups. I just dig them out with the surrounding soil, using a spoon, then transfer to the larger container. Because we had unusually warm weather at the time, I was able to do it outside, but then quickly moved them back inside.
**NOTE: Can you see the tiny hairs on the pink stems? Keep that information in the back of your mind for now…
It is a plus if the container has holes on the bottom for drainage of excess water. You can see the withered seed leaves still hanging on to this plant. They can be removed if you wish.
This next step is very important: Place the tiny root ball quite far down into the pot, then fill with soil. **Remember the little hairs on the stems? Here’s why that matters: When you plant deeply and cover up the stem, all these tiny hairs will grow into roots, which will ensure that the plant has a strong, solid root system. Cool, huh?
So you cover up until you’re about 1/2 – 1 inch from the bottom of the true leaves. The plant looks so tiny buried in the new pot, but it will grow very quickly from now on! Water, then place inside in a sunny, warm spot.
At this point the plants will grow very rapidly; pretty soon as much as several inches a week. That means they will need a lot more water as well. As they grow even taller, I often find myself watering twice a day. With holes on the bottom of the pots, and a tray underneath to catch excess water, I don’t worry as much about over watering as the plants absorb so much of it and the extra drains out. I give a good squirt or two in each pot. Sometimes I just wrap aluminum foil around the bottom of each pot to use as mini trays, and other times I use old cookie sheets to hold several plants.
I usually give away the extra tomato plants once they have been transplanted successfully to larger pots and continued to grow happily for another week.
When they are as large as on the next picture, it is on high time to select the ones I want to keep and get the rest of them out of my kitchen and on to their new homes. They are growing large and will need to be weathered to prepare them for outdoor planting. Weathering means to give them daily outdoor sun and air, a little more each day to help them get used to the outdoors to transition better. I will go into more detail about this simple process in my next post, Growing Tomatoes Part 2: Transplanting Outdoors and Care. In my third post on this subject, Growing Tomatoes Part 3, I will touch on a couple of common problems to be aware of, and what to do in this regard.
This is also a good time to stake the plants if not already done, to help hold them upright. I just use kabob skewers and string.
Very soon, the teeny, tiny sprouts will look like this, and indeterminate plants will only keep on growing from here:
My post Growing Tomatoes Part 2: Transplanting Outdoors & Care includes great information about how to transplant to large pots or in-ground, as well as general care. And in Growing Tomatoes Part 3, Common Problems & Solutions, I go through diseases and disorders and what to do to prevent or treat. I also have a post on tomato hornworms as these fascinating but destructive worms deserves a chapter all to themselves! They will make you choose between them and the tomatoes!
Seeding, transplanting seedlings, and growing larger tomato plants is quite easy, as you can see on these pictures. It is also very rewarding when you see your wonderful harvest of red, flavorful, homegrown tomatoes that you have grown from they were tiny seeds! Just a little bit of information on how and when will go a long way in knowing what to do to be successful. What a miracle, the life and potential that God has placed in these little seeds that are now producing scrumptious and nutritious food for your family!