When to Plant Tomatoes

There aren’t too many gardeners who don’t love growing tomatoes and eating them. When you think about tomatoes, maybe the first thought is popping a cherry tomato into your mouth while you’re still in the garden.

The flavor of a warm-from-the-sun tomato can’t be beat. And that’s just the beginning of how great tomatoes are! Then you think about the giant tomatoes like the Whopper tomato and how each slice is so large that it hangs over the side of your sandwich! And there are also the heirloom varieties that come in all sizes and colors, from pink to green, yellow to black and striped tomatoes to brown tomatoes. 

Tomatoes have variations in flavor too. Some have a very rich smoky flavor while others have a mild citrus flavor. You may be familiar with some of these varieties if you purchase tomatoes at a farmers’ market. Now, by growing your own, you can try a new variety each year.

Know Your Grow Zone

The first and most important information you need to know is what growing zone you are in. Included in that information is the last average frost date in the spring and the first average frost date in the fall. This is important for several reasons. Tomatoes like the warm temperatures as they originated in tropical areas, and they will die if exposed to frost. 

By knowing the average last frost date, you will know the earliest date that you can plant outdoors. But, remember, this is an estimate and there could always still be a later frost. Check the long-range weather report before you plant and always be prepared to cover your tomatoes to protect them from the cold if necessary. 

The same is true in the fall when an earlier than usual first frost hits. There may be a couple of cold nights followed by a couple of weeks of warm summer temperatures. Simply cover your plants for those days to extend the season and the harvest of your tomatoes.

Another reason to know your growing zone is that it will tell you about how long you have to grow tomatoes. There are early tomatoes that ripen quicker than the average time. It is fun to have at least one early variety so that you can be the first to pick ripe tomatoes from the garden. 

But for those gardeners who live in northern states, they’ll have a much shorter growing season between the last frost of spring and the first frost of fall. It is important to know just how many growing weeks you’ll have so you can pick the variety that will give you the most tomatoes before the growing season is over.

Deciding on Tomato Seeds or Tomato Plants

You have two choices when you want to grow tomatoes. You can purchase seeds, or you can purchase tomato plants. There are advantages and disadvantages to each. If you buy plants, they will be large enough to be planted directly in the garden as soon as the weather allows. The disadvantage is that you will have a substantially smaller number of varieties to choose from. 

The number of options will decrease even more if you want heirlooms like Black Krim or the large and bold-colored Kellogg’s Breakfast, or if you have an organic garden and need plants that have been started organically. 

Also, remember the tomato plants that you purchase have been growing in the shelter and warmth of a greenhouse. You must take the time to harden off the seedlings before you plant them in the garden or patio pots. 

Buying tomato seeds and starting them yourself will open the door to many more varieties of tomatoes. There are literally hundreds of different varieties of tomatoes in the world. Even a company like Park Seed has to decide which to grow and offer as plants because there are so many options to choose from.

Starting Your Tomato Seeds

Tomato seeds are easy to grow if you provide them with an environment they can thrive in. Tomatoes are best started indoors. The seeds should be planted five to seven weeks before the last frost date for your growing zone. Plan to plant your seedlings in the garden about two to four weeks after the last frost date.

Tomatoes want to be warm, and they need light. If you have a warm room in your home with bright sunny windows, you can be successful. The plants need a minimum of six hours of bright sun, so if you can’t provide these conditions naturally, you will need to supplement light and heat. 

The easiest way to grow your tomatoes is with a seed starting kit like the Park Seed Bio Dome.  The kit comes with bio sponges that have pre-drilled holes into which you place a single seed. 

The sponges fit into a waterproof tray that has a clear plastic domed cover to hold in moisture and prevent any cool draft from reaching the small seedlings. You can also use your own pots or some Jiffy Pots to start your seeds. 

Steps to Start Growing Your Seeds

You are almost guaranteed to be successful at growing your tomato plants from seeds by following these simple steps, including:

1. Find a Warm Growing Location — Place your tray of planted tomatoes in a room that stays at 70 to 75 degrees. If you don’t have a space that warm, supplement the heat with a plant heating mat. Your seeds should germinate and send up tiny shoots in just three to eight days. 

2. Provide Lots of Light — As soon as you see the shoots, it is important to move the plants into the light. As mentioned earlier, tomatoes need a bare minimum of six hours of intense sunlight, and even more is better. 

If you don’t have space in a south-facing window or patio door, supplement with grow lights. The light should be adjustable to keep it just a couple inches above the top of the plants so you can adjust it as the tomatoes grow. Grow lights should be used 14 to 16 hours each day.

3. Only Do Bottom Watering — Seedlings are susceptible to a fungal disease called damping off. Your plants may look healthy and strong and then, suddenly, they are lying on the surface looking like they have been snipped off at the soil level. There is no recovery from this damage. 

One way to help prevent it is to bottom water. Rather than sprinkling the baby plants from above and getting the plants and soil surface wet, add water to the bottom tray and allow the water to be drawn up into the soil.

4. Always Manage Air Flow — Another tip when growing seedlings is to simulate the wind blowing on them. Plant stems and root systems become stronger in reaction to the pressure from the wind. Gardeners who are starting a large number of seedlings often use a fan to gently blow over the plants for a few minutes each day. You can also simulate the movement from the wind by gently and lightly running your hand over the tops of your plants whenever you check them. 

Prepare Your Garden for Planting

Ideally, you started to get the garden ready for tomatoes last fall. If not, or if this is your first year, start getting the tomato garden ready about two weeks before you will be planting your tomatoes. 

Work the soil, mixing in a generous amount of compost and fertilizer specifically made for growing tomatoes. Cover the area with a tarp or plastic sheeting to prevent weeds and to help increase the temperature of the soil.

Hardening Off Your Tomato Seedlings

About ten days before you anticipate planting the seedlings in the garden, you’ll need to start the process called hardening off. This is meant to gradually get the plants used to the conditions outside. Start on the first day by bringing your plants out to a lightly shaded area for about two hours maximum. 

Even though the plants have been in bright light indoors, the plants will be sunburned if exposed outdoors. Sunlight is much more powerful, and your seedlings need to adjust. 

Each day, gradually increase the amount of time your plants are outdoors and the amount of exposure to the sun, until they are able to be outdoors all day and night. Keep an eye on the outside temperature during this time. You don’t want to lose your tomato plants now because of an unexpected cold snap.

Planting Seedlings in the Garden

Tomatoes can be grown in the garden without staking, and they will simply spread out on the ground. The reason most home gardeners don’t raise tomatoes this way is because they will take up more valuable space in the garden, the tomatoes are more difficult to harvest and there is usually more pest and water damage. 

If you decide to grow your tomatoes vertically, there are three choices: stakes, cages and trellises. If you want to use stakes, the stake should be very sturdy, about the width of a shovel handle.

The stake will have to be long enough to pound into the ground at least a foot or more. Tomato plants are very heavy when loaded with lots of fruit. Also, remember if you decided to grow indeterminate tomatoes, they will keep growing all season unless you top them off.

Cages will work for shorter tomato plants. They also can work well for grape and cherry tomatoes where there is less weight. There are all sorts of cages available. Some are quite inexpensive but that usually equates to shorter cages and less strength. Look for the tallest cage you can find with thicker wire construction that can support the weight of a full-sized plant.

Many gardeners are converting to trellis fencing. They use panels made for containing animals, so it is very durable. If you have a large number of tomato plants, this can be a good method. 

If you have raised beds, run the fence down the middle and plant on either side. The same trellis can be used to grow cucumbers, pole beans and other vining crops so you will still be able to rotate crops each year without moving fences.

Spacing Your Tomato Plants

There are some general guidelines on how far apart you should plant your tomatoes, including:

• Determinate and Compact Indeterminate — 2 feet apart
• Indeterminate Grown on Stakes — 18 inches apart
• Indeterminate Grown in Cages — 3 feet apart
• Container Varieties — Minimum 2-gallon pot

Growing Tips for Your Tomatoes

• Keep your tomatoes happy by watering about 1 ½ inches of water per week. Stay consistent, as tomatoes don’t like to have drought one week and extra water the next. Don’t pick the tomatoes right after watering because if the tomatoes are picked before you water, the flavor will be intensified.
• Use mulch to lower the competition from weeds for nutrients and water. Mulch will also preserve water so that it is not lost to evaporation, and it will keep the ground temperature more stable.
• Keep an eye out for insect pests and their larvae stage and treat your plants immediately when they are discovered. Consider companion planting your tomatoes with marigolds. The marigolds repel some of the pests but attract pollinators.

Timing the growing of your tomatoes has many factors, and the most important is based on the timing of the frost stopping and starting for your grow zone.  Have fun growing your own tomatoes this gardening season!