The tomato plant, Solanum lycopersicum, is one of the most popular plants for the home garden because they are easy to grow, there are many different cultivars and the fruit has a wide array of culinary uses. It is common to think of Italian cuisine when thinking about tomatoes, but tomatoes are actually native to Central and South America where they are an important part of Latin culture and cooking.
Popular Tomato Cultivars
Tomato cultivars include heirloom and hybridized varieties.
Heirloom tomatoes are grown from seeds that have been passed down for generation
and have the same selected characteristics for generations. These characteristics include great flavor, irregular shapes and a rainbow of colors. Although heirloom tomatoes are known for their great flavor, they are prone to cracking and have less disease and pest resistance than hybrid varieties.
Popular Heirloom Varieties:
Hybrid varieties have been bred by growers to produce desirable characteristics such as hardiness, earlier maturity, color, flavor, disease resistance, size and shape. Growers often have better success with hybrid tomato varieties because they are bred to be improved cultivars.
Popular Hybrid Varieties:
Bush Early Girl
Indeterminate vs. Determinate Growing Patterns
There are two types of tomato plant growing patterns.
Indeterminate tomato plants are vining plants that have no determined growth size or fruiting date. They will continue vining and fruiting until they die off when the weather gets too cold for them to survive. Due to their large, vining growth, they must be trellised or staked early to keep them from laying on the ground. If allowed to lay on the ground, the moisture and soil bacteria can lead to rot of the foliage and fruit.
Some indeterminate tomato plant varieties include:
Determinate tomato plants have a determined growth size and fruiting time frame. These plants typically grow to 2-3’ tall and set fruit all at once, earlier in the summer months than indeterminate types. They don’t typically need support structures due to their smaller bush size, but support is recommended as these plants can become top heavy, especially when fruiting. Supporting these plants will also protect them from strong winds.
Some determinate tomato plant varieties are:
Bush Early Girl
How to Grow Tomatoes from Seed
When to start
Starting tomatoes from seeds is best done indoors in late winter or early spring when the temperatures outside are too cold for proper germination. If growing from seed, check the package for the ‘days to maturity’ to find the variety that is best suited for your region. Days to maturity is the amount of days it takes a tomato to ripen from the date of transplanting. If you live in a colder climate with a shorter growing season, it is best to choose a variety with a shorter ‘days to maturity’.
Amish Paste: 80 days
Black Krim: 70 days
Brandywine: 80-100 days
Cherokee Purple: 80-90 days
Constoluto genovese: 75 days
Green Zebra: 75-80 days
San Marzano: 85 days
Better Boy: 70-75 days
Bush Early Girl: 54 days
Celebrity: 90-100 days
Lemon Boy: 72-80 days
Sun Gold: 65 days
Juliet: 60-70 days
Find your planting date by zip code here!
Creating the ideal growing environment
Seed germination requires two things: moisture and warmth. The soil used to sow the seeds must stay moist at all times until germination. Letting the soil dry out, even for a short time, can stop the germination process. Keep the seeds in a location that gets the most warmth. Ideally, the soil medium temperature must be at least 60° F. Warming mats can be used to increase germination tray warmth. With proper moisture and warmth, germination can take about 5-10 days.
If sowing seeds directly in the ground, wait until spring when night time temperatures have increased to at least 55° F and the soil is at least 60° F. Bury seeds ½” deep and at least 2’ apart. Multiple seeds can be placed in each hole to increase the likelihood of germination. If multiple plants germinate in one hole, all but one should be pinched off, keeping the strongest seedling. The strongest seedling should have the thickest stem and leaf set.
Take into account germination rates
It is best to sow more seeds than you plan on growing because germination rates are not always 100% successful. Germination rates can decrease if the seeds were not stored properly by the seller or if trying to germinate them in less than ideal conditions.
Source seeds from reputable seed companies
Purchase seeds from reputable seed companies. Seeds can be purchased online from seed companies or from your local gardening stores.
Reputable online seed companies:
Johnny’s Selected Seeds - A large selection of fruit, vegetable, herb and flower seeds.
Baker Creek Heirloom Seeds - A large variety of rare or hard to find seed varieties, large heirloom selection.
Seed Savers Exchange - A large variety of heirloom seeds.
Tools Needed to Start Seeds:
This pack includes peat moss germination pucks, trays and domes
An alternative is to buy a seed starting mix and fill any type of container
Seed Starting Steps
Step 1: Fill seed tray with soil medium and place on a warming mat. (if using peat moss pucks, just place the tray on the warming mat.)
Planting in individual celled trays puts less stress on the seedling’s roots when needing to pull them apart in open trays.
Step 2: Poke ¾” holes in each cell. (meat moss pucks are designed to already have holes poked.)
Step 3: Moisten the soil medium you are using. (Peat moss pucks should be soaked until they expand.)
Step 4: Place one seed per tray cell or puck. (Seedlings will compete for space and nutrients if multiple seeds are planted in a single cell.)
Step 5: Lightly cover the seeds with the soil medium and press firmly. (soil medium that is covered too loosely can uncover the seed when watered)
Step 6: Fully water the soil medium until it holds onto moisture.
Step 7: If using a dome, place it on top of the tray. Plastic wrap can be used in place of a dome. This allows the soil to hold onto moisture and warmth.
Step 8: Turn on the grow light. Grow lights will provide warmth and will help the seedlings grow strong.
Step 9: Keep watering the soil medium, ensuring it does not dry out. This can be done with a watering can or mister.
Step 10: Leave the grow light and warming mat on until the plants are ready to be transplanted outside. Plants are ready to be transplanted when they have at least two sets of true leaves.
When the seedlings germinate, they will have two leaf-like structures called cotyledons. These provide the seedlings nutrients and help the plant photosynthesize until it is strong enough to produce true leaves. It is unnecessary to fertilize your seedlings until they are ready to be transplanted. Fertilizing too soon can cause the plants to become leggy and weak.
Using a Container vs. Ground Planting
If you don’t have the space or availability to grow tomatoes in the ground, they do great when grown in large pots. This is especially beneficial if you are renting your home or want a low maintenance option. If growing your tomato plants in pots, ensure they are at least 5 gal pots to house the plant’s large root system.
Benefits of container planting:
can be moved
more control over soil framework
Drawback of container planting:
Soil dries out quickly
nutrients leach out quickly
can tip over
Benefits of ground planting:
More space to grow
soil holds onto moisture and nutrients better
Drawback of ground planting:
more susceptible to diseases and pests
If you decide to plant your tomatoes directly into the native soil in your yard, it is important to know the soil health. Soil texture, pH and nutrient levels are the most important factors to consider. Soil tests can be purchased online or you can take a sample of your soil to a local lab to get tested.
Online soil testers:
Luster Leaf Rapitest - Tests for pH, nitrogen, phosphorus and potash
Rapitest Soil Probe - pH, soil moisture, sunlight
Soils that are sandy or clay-like should be amended with compost and planting soil to add the right structure and nutrients. (Read more below on tomato plant nutrient and pH requirements.)
How to Transplant Tomato Seedlings
Whether you are transplanting seed grown or store bought transplants, you should wait until the night time temperatures are above 55° F and the last frost date has passed. Transplants should be brought inside or covered with garden fabric if nighttime temperatures drop below 55° F.
Tomato plants are able to produce roots along their entire stem, so the more stem that is buried, the stronger the plant will be.
Step 1: Dig about a 6” planting hole (Increase or decrease the size depending on the size of the plant.)
Step 2: If planting multiple plants in the ground, dig holes at least 2 feet apart.
Step 3: Place about ⅔ of the plant in the planting hole (the very lower leaves can be pinched off for deeper planting.)
Step 4: Position support stake or cage around the plant.
Step 5: Water the plant until about a 6” diameter of soil is wet.
Soil, Nutrients, pH
Tomatoes are heavy nutrient feeders, so regardless of growing in containers or in the ground, the soil must be nutritious. Adding fertilizers regularly will allow tomatoes to be able to produce a high yield of nutritious and flavorful tomatoes. Tomato specific fertilizers will ensure your plants are getting the necessary micronutrients (calcium, magnesium, sulfur) and macronutrients (nitrogen, phosphorus, potassium).
Tomato Specific Fertilizers:
Tomatoes benefit from having their soils slightly acidic with a pH between 6.0 and 6.8. If your soil pH is lower than 5.5 or higher than 7.5, your tomato plants may not be able to take up enough nutrients to produce fruit.
The acidity of the soil allows the plant to take up water soluble aluminum ions which help the plant absorb nutrients. Aluminum is naturally present in soils, but can become depleted over time. Therefore, it is important to acidify soils by adding a layer of soil acidifier near the base of your plants when planted. If your soil is too acidic, add garden lime to raise the pH.
Temperature and Sunlight
Tomato plants love sunshine and warmth. That is why they grow so well in the summer months. They need at least 6-8 hours of direct sunlight a day to produce fruit. The ideal temperature to grow tomatoes in is between 65°F and 85°F.
If the nighttime temperature dips below 55°F or the daytime temperature goes above 90° for long periods, the plants can get too stressed to produce fruit or the fruit can become diseased. One common problem with extreme temperatures is called ‘blossom drop’. This occurs when blossoms fall off the plant prematurely, reducing fruit yield.
Regular watering is imperative to tomato growth, especially during the fruiting stages. The average watering schedule is once a week, but can be more often in hotter climates.
When watering, soak the entirety of the potted soil and up to a 6” diameter if growing in raised beds or in the ground. When growing in containers, ensure there is enough drainage so the moisture doesn’t collect at the bottom. The first sign of under watering is wilting of the plant’s foliage. Over watered tomato plants will quickly rot and turn mushy.
The consequences of inconsistent watering is typically seen in the fruits.
One of the most common signs of inconsistent watering in tomato fruits is called ‘blossom end rot’. This disease is caused by a lack of calcium. Plants need water to be able to take up the nutrients from the soil and are unable to during periods of drought.
Another common sign of inconsistent watering is fruit cracking. This occurs after long periods of droughts, followed by heavy watering or rains. tomato fruits to crack. This occurs when the flesh of the fruit grows faster than the skin.
Pruning tomato plants is mainly done to control the size of the plant and to improve fruit yields. Indeterminate, vining tomato plants often need the most pruning due to their long growth. If your plant begins outgrowing its support structure, its height can be cut back.
Pruning off side shoots referred to as ‘suckers’ is the most common pruning done on indeterminate tomato plants. Suckers form in the crotches between the main stem and leaves. These suckers will eventually turn into main stems. The more stems an indeterminate plant has, the more potential for fruit. Reducing the amount of main stems there are, the less fruit there will be, but the fruit will be larger. If you want high fruit yields and don’t care as much about the size of the fruit, eliminate pruning altogether.
Determinate tomato plants generally don’t need as much pruning as indeterminate plants because of their shorter height and bushier growth. The only pruning that should be done on determinate plants is removing suckers below the first flower cluster.
Harvest times can fluctuate depending on your growing zone, cultivar and the plant’s growing conditions. It is best to allow tomatoes to ripen on the plant for the best flavor. Tomatoes begin to ripen once the fruit begins turning from solid green to the characteristic reds, purples and yellows. If tomatoes are picked when they are solid green and have not begun turning in color, they will never ripen. These can be used to make fried green tomatoes!
Ripe tomatoes should be slightly firm and have little to no green left on the fruit, unless the cultivar is a green color tomato. If tomatoes are kept on the plant for too long, they will begin to rot and attract pests.
Each plant can produce between 8-10 lbs of tomatoes.
It is common for heirloom tomatoes to crack when they begin to ripen. These cracks can attract insects much easier than hybrid varieties.
Some common pests to tomato plants are aphids, leaf miners, stink bugs, potato beetles, cutworms, hornworms, loopers, white flies and birds. Horticultural oil can be sprayed on the plants, especially under the leaves to prevent smaller insects like aphids, leaf miners and white fly insects from devouring the plants. Larger insects such as stink bugs, potato beetles and worms can be physically removed or sprayed with Bt (bacillus thuringiensis).
Birds become pests of tomato plants when the fruits begin to ripen and turn from green to colors like reds and yellows that they can see. Wrapping tomatoes in white garden cloth will mask their colors and deter birds. This cloth works as a barrier for insects as well.
Tomatoes are plagued with a variety of fungal diseases that can damage both the foliage and the fruits. Heirloom varieties are more likely to be afflicted with these diseases because they have not been bred to be resistant to them like hybrid varieties are. Hybrid cultivar seeds will be labeled with the diseases they are resistant to with the below letter codes:
LB - late blight
V - verticillium wilt
F - fusarium wilt stain I
FF - fusarium wilks strains I & II
N - nematodes
T - tobacco mosaic virus
A - alternaria
If you have any more questions about how to care for your tomato plants or when to plant them, we will be happy to assist you in a virtual telehealth appointment with one of our Plant Specialists. Please click on one of the options below to book an appointment.