when to plant tomatoes

When to Plant Tomatoes for Healthy Produce

Ian Mutuli
Updated on

Tomatoes are delicious and are used in endless food recipes. You can never go wrong with one or two while making your meals. Therefore, if you'd like to have a small garden and are wondering when to plant tomatoes, you are at the right place.

You could even be thinking of starting a tomato farm and not sure when to start planting. However, we are here to guide and help you understand what you need to grow tomatoes.

Tomato plants are warm-season crops and cannot withstand frost. Therefore, it is important not to put the seeds in the soil too early. However, this will also depend on your region.

In most locations, the soil will still not be warm enough to plant tomatoes outdoors until late spring or even early summer.

Tomatoes also come in varieties, which may affect their planting time as some have longer growing season requirements than others. As a gardener, you can also choose to use starter plants or transplant seedlings instead of starting from seeds.

However, if you plan to start from scratch, you can still plant from seeds indoors till the outside soil is warm enough to support the young plants.

When Should You Plant Tomatoes?

As we already mentioned, when to plant tomatoes depends on your region. These plants are long-season and heat-loving. The time you start planting will also be determined by whether or not you plant tomatoes from seeds or seedlings.

When to Sow Tomato Seeds Indoors

Tomatoes germinate around 64°F (18°C)- 77°F (25°C). Therefore, it is recommended to plant the seeds covered whether you plan to grow them in a greenhouse or outside.

If you plan to transplant them outside, you can plant tomatoes six to eight weeks before the latest frost date in your area.

Sow thinly in seed sowing compost-filled trays, loosely cover with compost and water. Seeds will germinate in about eight to ten days if kept in a bright area at roughly 65°F (18°C) - preferably in a propagator or covered with a plastic bag. If you only want to grow a few plants, sow them separately in little pots.

Image: Modern farmer

When the tomato seedlings have two 'actual' leaves, they should be plucked out and repotted into 9cm pots to continue growing before being put outside. As the seedlings continue growing, ensure you keep them in the sun for 10-14 hours per day. You can even use artificial grow lights if you start planting in the seasons when the days are short.

Keep watering your seedlings but do not let them get soggy. If you planted too soon, you might need to repot your seedlings again before they are ready to be outside.

Set the pots outside in a sheltered spot once the outside soil temperatures have risen and the young tomato plants are ready for the outdoor conditions. Do this for an hour daily for one week or two until your plants have adjusted to the outdoor weather.

When to Plant Tomatoes Outside

When should you plant tomatoes outside? This may be a tricky question; however, it is simple. First, you should wait till the risk of frost has passed and the weather conditions are favorable, and the soil is warm.

Image: Freepik

Tomatoes are normally transplanted one to four weeks outdoors following your area's last frost date. Most tomato plants are replanted outside once the lowest overnight temperatures are slightly above 50°F. This normally happens a few weeks from the last first frost date in the area.

If you plant tomatoes outside when the nighttime temperature is below 50°F, the plants grow very slowly. When the temperatures reach below 43°F, the seedlings may get damaged.

Tomato Plant Problems

Once you plant your tomatoes, they will likely encounter diseases and pest infestation challenges. So, ensure you watch out for infections and infestations, which are sometimes caused by excessive use of fertilizers. Some of the tomato plant diseases include the following;

i). Powdery Mildew

Powdery mildew is a fungal disease that leaves the tomato leaves with white spots or a dusting of white. This disease is manageable and doesn't have to worry you.

ii). Cracking

The skin of the fruit will crack if it grows too quickly. This is typically caused by uneven watering or moisture from weather conditions, such as (very rainy days mixed with dry periods). Maintain moisture levels by watering and mulching regularly.

iii). Mosaic Virus

Causes distorted leaves and early growth to be narrow and twisted, as well as yellow mottling on the leaves. Unfortunately, diseased plants must be destroyed (but not composted).

iv). Early Blight

Early blight is a fungus that forces leaves to fall off, and because of the humid conditions and high temperatures in July, the risk of blight increases. It begins with dark, concentric patches (brown to black) on the lower leaves and stems about 1/2-inch diameter.

Image: ncsu

If you detect the disease early, your plant may survive after you kill the contaminated leaves. Good ventilation and removing the lower leaves as the tomatoes mature are the best defenses for outdoor tomatoes.

This also aids ripening because tomatoes receive the most solar exposure.

v). Late Blight

Image: Gardentech

Late blight is a fungus that forms grey, rotten patches on fruits and leaves later turn brown. Persistent moist weather aids in the spread of the disease. Unfortunately, there isn't much you can do after your tomato gets affected by late blight.

vi). Blossom-End Rot

This disease results from calcium imbalance, leading to the development of dark and sunken spots on the bottom side of the tomato plant. The calcium imbalance is normally a result of uneven watering, and you can prevent it by keeping your soil evenly moist.

How Can You Prevent Tomato Plant-Insect Infestation?

Besides crop diseases, we already mentioned that pests could infest tomato plants. However, before that happens, you will need to try some preventative measures to ensure your plants do not get manifested by pests.

a). Rotate crops after at least three years and try as much as possible to avoid other members of the tomato plant. Such plants include eggplants and pepper

b). Do not plant just any crops; instead, plant disease-resistant crops. Such crops are usually coded and listed on the seedling or seed packet.

c). When planting tomatoes, ensure you use well-draining soil. Also, mix in compost or organic matter.

d). Solarize your soil; if the problem is too much, you can treat it by using plastic to cover the soil during the hottest summer days for 6-8 weeks. This will give the sun time to destroy the bacteria.

e). When you see infected plants, destroy them as soon as possible. This will prevent the pests from spreading to uninfected plants. Be careful not to put the discarded plants in the compost pile.

How Can You Get the Timing Right When Growing Tomatoes?

To find out the best time to plant your tomato seeds and plants, you can start by figuring out when you plan to plant them outside and calculating backward. So let's find out how to do that.

1. Calculate the Optimal Planting Date

The most important point to keep in mind is that you need to wait until after the last frost date, as indicated by your USDA Hardiness Zone.

This can be hard, but do not be tempted to plant early even if your spring weather is unseasonably warm if you need the best results.

Because tomatoes are true warm-weather plants, planting them too early could kill them. Although a few transplants may survive a few frosty nights, their growth could get stunted, and they may be more susceptible to diseases and pests.

Note that first and latest frost dates are merely estimates based on your growing zone's average.

2. Temperature

Tomatoes need night temperatures to be consistently above 50°F. You can use a soil thermometer to confirm. However, if you do not have a thermometer, you can use a makeshift method whereby you stick your finger in the soil; and if you can't stick it there comfortably for a minute, the soil is probably too cold.

3. Days to Maturity

While it could be safe to plant after the last frost, waiting a few weeks till the temps have warmed and the days have lengthened may result in better, happier plants.

However, some varieties take a long time to mature, and it's just as critical to ensuring there will be enough warm days for crops to produce fruit before they're damaged.

First, you will need to figure out when you expect the first frost to fall. Then, use the number of days to maturity to count backward. The number of days to maturity is often indicated on the packet of seeds.

4. Sunshine

Tomato plants need warm temperatures and enough sunshine to be healthy. Before planting tomato plants, ensure the sun is high in the sky for a large part of the day to receive at least six hours of full sun exposure.

Image: Fromseedtocrop

Ian Mutuli

About the author

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.