Growing Guide: Tomatoes

Tomato Description:

Tomatoes are an essential crop for any home gardener. Whether you have a large garden or limited space, growing tomatoes is hugely rewarding and easy enough even for beginners. 

Tomatoes fall into one of two types: determinate and indeterminate. Determinate tomatoes are usually referred to as “bush” types and develop their fruit all at once near the middle of the growing season. Bush tomatoes can benefit from caging to support their weight as the growing season progresses, though it’s not usually necessary. Determinate or bush tomatoes are the best for container gardens since they stay relatively compact.

Indeterminate tomato varieties, also known as “vining” tomatoes, produce fruit all season long. They tend to eventually get too heavy for their own stalks, so it’s important to give them some support as they grow. Scroll down to the Tomato Care Guide section for more information on caging and staking tomatoes.

What is the best container for growing tomatoes?

Tomato roots are somewhat shallow and spread out horizontally, so it’s recommended to plant just one tomato in each container. A 10-gallon bucket is a good size, but any container at least 18 inches deep and with adequate drainage holes should work for determinate varieties. Indeterminate tomatoes should be planted in larger containers since they typically grow much taller than determinate varieties. No matter what type of tomato you’re growing, bigger is better when it comes to container size. 

How do you germinate tomato seeds?

Because tomatoes take so long to mature, most gardeners choose to buy seedlings from a nursery. However, it’s totally possible to grow tomatoes from seeds – you’ll just need to start early in the season.

Fill your seed tray or small pots with a seed-starting medium. Plant tomato seeds about 1/4 inch deep in each container. Keep the sprouting seeds at a constant temperature of around 70-80°F for optimal germination. The soil should be kept consistently moist, never dry or waterlogged.

When should you plant tomato seeds?

Tomatoes will not survive a frost, so it’s essential to get the timing right when transplanting them into their outdoor homes. In general, you can start germinating the seeds indoors about six to eight weeks before the final frost of the season. Transplant them outdoors when all danger of frost has passed and nighttime temperatures consistently stay above 50°F. 

Direct sowing (planting the seeds directly in the ground or growing container) is possible if you have at least four months of warm, sunny, frost-free growing season. However, we strongly recommend starting your seeds indoors to minimize the risk of losing some or all of your crop.

Before you put them in the ground, you’ll need to “harden off” the baby plants over the course of a week to get them used to the elements. Place the tray or pots outdoors in the shade for two hours the first day, then gradually increase the time they spend outside (and the amount of sun they receive) each day. After about a week, they should be ready to go into their permanent homes. Pinch off the bottom set of leaves before planting them in their permanent outdoor homes. 

Tomato care guide:

Tomatoes need full sunlight to thrive, so plant them in a location that receives six to eight hours of direct sunlight every day. Keep the soil evenly moist at all times. Don’t wait until the soil gets dry and then overcompensate by overwatering; any period of drought can make the fruit bitter. Covering the ground with a layer of mulch, straw, or landscaping rocks can slow the rate of evaporation and keep the ground moist for longer.

Water early in the morning to give the plants enough water to get through each hot summer day.  Be careful to water the soil and not the leaves, as wet leaves can encourage leaf rot. 

Once established, indeterminate tomatoes will take over your garden if you let them grow freely. This may seem like a good thing, but the plants can quickly get out of hand. If they put all of their energy into expanding outward, they’ll spend less energy producing fruit, so you’ll want to keep them somewhat compact. After the plants have established their main branches, pinch off any new stems that try to sprout from those branches. This keeps the plant from growing out of control and allows more sunlight to reach all of the leaves. 

Most gardeners do not prune determinate tomatoes other than pinching off new growth between the soil and the first flower cluster. This type of tomato doesn’t divert energy from fruiting into leaf growth, so pinching off new growth won’t encourage fruit more production – in fact, you’re just throwing away the tomatoes that would eventually form on the discarded branches. Determinate tomatoes also have a maximum size determined by genetics and won’t grow any more after reaching their mature size. However, some light pruning may be appropriate to keep the plants to a manageable size when growing in containers. 

Indeterminate or “vining” tomatoes need support for the full growing season to prevent the stems from tipping over or breaking and causing the tomatoes to sit on the soil. Cages and stakes should be placed in the soil at the same time as the seedlings are planted. Tomato cages are affordable and readily available from most nurseries and home improvement stores. You can reuse them every year, so the few dollars you spend on each cage is a worthy investment in your future garden. Stakes can be anything from fence posts to bamboo poles to metal poles made specifically for staking tomatoes.

Once indeterminate tomato plants reach a height of 10 to 12 inches, you can begin loosely tying them to their stakes. As the plants grow, continue securing new growth to the stakes every 12 inches or so – or sooner if the plant starts to bend or grow sideways.

Harvesting and storing tomatoes:

The time to harvest tomatoes varies by cultivar, but most tomatoes are ready 60-85 days after transplanting. Look for tomatoes that are firm, but not hard, to the touch and have no green spots remaining on the skin (unless, of course, you’re growing one of the varieties that are supposed to remain green). 

To harvest a ripe tomato from the plant, gently twist or cut the tomato stem using clean pruning shears. Leave the calyx (green stem) attached to the tomato to extend its shelf life.

If frost threatens or tomatoes are still green at the end of the growing season, harvest them and let them ripen indoors in a warm, dark place. You can place them in a paper bag with a ripe banana to speed up the process.

Harvesting tomato seeds:

Saving tomato seeds is a great way to continue growing your favorite types of tomatoes for years to come. 

Select fully ripe, healthy tomatoes from your desired variety. Cut the tomatoes and scoop out the seeds along with the gel into a small glass jar. For tiny tomato varieties, you can just pop them open with your fingers and squeeze the seeds and gel into the container. Be sure to label the jar with the tomato cultivar so you can keep track of which varieties your seeds will produce.

Add a small amount of water to the container and cover it with a cloth or plastic wrap. Allow the mixture to ferment for 2-5 days, stirring daily to prevent mold. After fermentation, rinse the seeds under running water in a fine mesh sieve. Remove any remaining gel and debris.

Spread the cleaned seeds on a paper towel or screen to dry, away from direct sunlight. They can take up to three weeks to fully dry, so be patient! Once they are completely dry, store the tomato seeds in labeled envelopes or airtight containers in a cool, dry place.