Growing tomatoes from seed

Some new gardeners are understandably intimidated by the prospect of growing tomatoes from seed, but with a little planning and know-how, it's surprisingly easy and fun!

The most important part of all is timing. You need to start the seeds indoors 6 to 8 weeks prior to your last frost of the spring. Don't know when that is? Plug in your zipcode on our Frost Charts page and we'll tell you.

What you'll need:

1) Potting mix. We recommend you use "Seed Starting Mix" that you can buy at your local hardware store or garden center. Don't reuse old potting soil for this step; you want new, fresh and sterile seed starting mix or else you really risk disease and other problems.

2) Small containers for the potting soil. These can be seed starting cells, or even things like repurposed yogurt containers. Just make sure they are clean and have holes drilled in the bottom for good drainage.

3) A light source. If you have growlights, you're all set. Otherwise, you can get by with a sunny window sill.

4) A warm location, or a heated seed starting mat.

The seed starting mix is probably going to come from the bag extremely dry, so you need to moisten it before you do anything else. I like to get hot water and mix it into the soil in a large bowl, stirring and breaking up the pieces until I end up with a nice fluffy moist mix. The hot water cools down quickly during this step.

Fill your containers with the soil, and then sow a tomato seed just under the surface of the soil. You want it covered but not buried too deeply.

Just one seed per container? Yes. We test our seeds before selling them, and generally we see 100% germination on all our tomato seed lots. You can count on those seeds to germinate, so don't waste seed by planting too many in one container. Although we do try and separate seeds during the harvest process, you may sometimes find small clumps of multiple seeds in your packets. Separate these clumps into individual seeds before planting.

Water lightly and keep consistently moist until germination occurs (usually within a week), keeping the pots in a warm spot. If the seeds dry out, they will die, so it's important to check them daily and water the soil if necessary. You can cover the pots with a plastic bag to help maintain the soil moisture but be sure to remove it once plants appear. The tomato seeds germinate best if the soil is between 75 to 90°F.

Personally, I usually start my seeds in a shallow tray and I carefully space each seed a couple inches apart. When they germinate, they look like the photo below, and within a week after germination I will use a spoon to pull each one up to pot them into individual containers.

While they grow, full light, and cooler temperatures (60 to 70°F) will help to prevent the seedlings from becoming too leggy. After the seeds have germinated, place them in a location that receives a lot of light and good air flow. I keep a gentle fan blowing in their area at all times. A south-facing window should work to provide light, but if this is not an option, a lamp fixture rigged so that it is a couple of inches above the plants will work. If they do not receive adequate light, they will become spindly.

The ideal situation for starting seeds indoors is an actual grow lights setup. Modern LED grow lights have become an excellent and affordable option.

After the plants have their second or third set of true leaves, and before they become root bound, transplant into larger 4-inch pots. This transplanting step will allow the plant to develop properly and promote root growth. Harden off plants before transplanting outside. Be careful while transplanting so that you do not disturb or damage the roots too much. We recommend planting them deep, burying some of the stem under the soil.

Young plants are very tender and susceptible to frost damage, as well as sunburn. Plant them as early as you can, but be prepared to cover them if a frost surprises you one night. We cover them with buckets, placing them in the evening and removing the buckets at first light in the morning.

Tip: You should avoid giving tomato plants too much nitrogen, especially before the fruit sets. It is far better to plant them into a location that has healthy soil with high levels of organic matter worked in.

Tip: Over watering may help to produce larger fruit, but flavor may be reduced. Additionally, splitting and cracking can result from uneven and excessive watering.

Selection tips: Determinate types ripen over 3 to 4 weeks and their bushes generally do not need staking. Indeterminate types continue to grow even after the fruit sets and ripen continuously until a frost arrives. Looking for dwarf plants? Check out the Dwarf Tomato Project, with over 150 varieties of beautiful and excellent tasting tomatoes on dwarf plants.

Too Many Tomatoes? Although indeterminate heirloom tomato varieties typically ripen throughout the growing season, there are times when you may end up with an abundance of fruit and little time to cook into sauces or can. One solution is to freeze some for use during the winter months. Package them for the freezer by placing them into a freezer bag and placing the freezer bag in a brown grocery bag for extra protection. When ready to use, hold the frozen tomatoes under hot water for a few seconds. The skin will split open and slip off easily allowing you to use them in you usual recipes.

Please remember that the maturity dates we show on our website are from the time of setting plants into the garden. Additionally these dates will vary from location to location and even from year to year. They are for rough planning purposes only.

Starting your own tomato plants from seed is a richly rewarding and cost effective way to get a lot of plants, more than enough for your own use as well as some to share with friends and family.

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