There’s nothing more satisfying about gardening than pulling the first ripe tomato of the season off the vine, still warm from the sun. But without adequate and bright energy from the sun, our tomatoes would be bland, watery, and flavorless. But how much sun do tomatoes need to ripen without splitting?
Our comprehensive tomato sun requirements guide is about to reveal how much sun tomatoes need and what to do if your tomato plants aren’t enough. By the end, you’ll be a tomato-growing expert!
(Our team has tons of experience growing tomatoes. We want to show you every tomato hack we’ve learned! Sound good?)
- How Much Sun Do Tomatoes Need?
- Can Tomato Plants Grow In the Shade?
How Much Sun Do Tomatoes Need?
According to Rutgers University, your tomato plants need about eight hours of sunlight daily. And it’s preferably in full, direct sunlight. At least six hours of sun will do in a pinch, but your plants will be smaller, and the fruits won’t be as flavorful.
Tomato plants need a lot of sunlight because they produce large bright fruits with a good amount of sugar. It takes a ton of energy from the sun for fruit production, so they need to be grown in a warm, sunny region and growing season.
If you want your tomato plants to produce juicy tomatoes consistently, you’ll need to provide them with at least six hours of direct sun. Choosing the right time for planting your tomatoes is essential to getting a good harvest.
The best time to plant tomatoes is in late spring or early summer. Summer is perfect for tomatoes because the temperatures are warm, and there’s no danger of frost. If you’re starting your tomatoes from seed, you’ll need to give your tomato seedling even more sun – up to 10 to 12 hours per day. But be careful when the weather gets hot – young plants may not cope in extreme conditions.
Take the weather here in the tropics as an example. We regularly experience temperatures over 104 degrees Fahrenheit! During days like these, young seedlings do not cope with the full sun. It’s too hot, too humid – just too much in general. To grow healthy tomato plants in a hot growing zone, they do not mind some protection from intense heat. Particularly during the hot afternoon sun!
It always surprises me how much tomatoes love the sun. A successful tomato crop depends on it. However, there is a limit.
What Happens if My Tomato Plants Don’t Get Enough Sun?
If your tomato plants are not getting enough full sun, they will produce small fruits that lack flavor. The sugar content in the fruit will be lower, and the overall yield of your plants will be smaller.
In extreme cases, your tomato plants may stop producing fruit altogether. If you think your plants are not getting enough sun, here’s how you can help them.
Try to move your plants to an area that gets more sun. If that’s not possible, you can try using grow lights. Grow lights mimic the sun and give tomato plants the extra light they need to flourish.
(Obviously, grow lights aren’t as good as the sun. But grow lights are perfect for nursing small tomato plants before transplanting them outside.)
Does the Sun Help My Growing Tomatoes Ripen?
Contrary to popular belief, light does not affect ripening. Tomatoes do not need light to ripen. Exposing tomatoes to direct sunlight can heat them to levels that prevent pigment synthesis. Too much direct sunlight can also sunscald the tomato fruit.
Too much heat in severely hot climates such as deserts can cause the tomato plant to shut down ripening all together. The best way we’ve found to prevent this is by giving your tomato plants some afternoon shade and adequate water in these ultra-hot regions.
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Can Tomato Plants Get Too Much Sun?
If tomato plants experience high levels of sunlight per day, especially during hot weather, extreme heat (such as a heat wave), or when they are already under defoliating stress, they may suffer from sunscald.
Sunscald can damage tomato fruits as they develop and mature. If a tomato fruit gets sunscalded, it will develop discolored patches on the side where the sun hits it directly. If the sun dries out the spots on the fruit, it becomes dry, shriveled, and eventually rots.
Different types of tomatoes can handle sun exposure more than others. If the tomato plant doesn’t have many leaves and is more exposed, it will be more sensitive to high-intensity light than other tomato plants.
The excess sun may result in the soil losing water rapidly through evaporation, even when temperatures aren’t that high. If you notice your plant’s leaves drooping and fruit no longer forming or falling off, sun damage may be the cause.
Don’t forget to protect young or newly planted tomato plants from the sun. Excessive sun exposure can harm young transplants by inhibiting leaf growth, causing the leaves to turn gray and eventually die. (That’s why we advise hardening your tomato plants before planting them!)
If the temperature is too hot and there’s intense sunlight, the flowers may fall off. Tomato plants usually won’t bear fruit if the temperature during the day exceeds 95 degrees Fahrenheit. Unripe fruits left on the plant will stop ripening and may even fall off. Once temperatures cool, larger fruits that stay on the plants may resume ripening.
How To Protect Your Tomato Plants From the Bright Sunlight
If you think that sun exposure or excessive heat is stopping your tomato plants from growing or they can’t produce fruit, here are a few things you can do to help them.
- Build a shading structure for your tomato plants using lattice, shade cloth, or burlap. Ensure the shading material is not too dense, as it can trap heat.
- Create a ground cover that can help shade the roots of the plants while trapping the water in the soil. You can use landscape fabric, straw, or other organic matter, such as mulch. (We prefer compost mulch over landscape fabrics.)
- Plant your tomatoes where they will get moments of shade or indirect sunlight. Consider planting them next to taller plants, a cucumber trellis, on the north side of a fence, or near a small tree.
- Set up a drip irrigation system to water the roots directly and prevent irregular watering, evaporation, and dehydration. (But be careful not to soak the leaves.)
- Monitor the temperature using a thermometer, especially during hot days. If it gets too hot, provide temporary shade for your plants until the temperature drops.
- Choose tomato seedlings and cultivars that are more heat tolerant and prefer full sun locations. These tomato plants will withstand the midday sun better than other varieties.
Tomatoes usually do well with a light intensity of six or more hours and afternoon heat, but the above tips should help foolproof your crops.
Which Sun Is Best for Tomatoes? Morning or Afternoon?
Should you use morning light or afternoon sunlight to grow your tomatoes? The truth is, these sun-loving plants love both early morning sunlight and afternoon sun. But you should plant them where they receive morning to midday sunlight, if possible.
We love giving our tomatoes planted outside plenty of morning sunlight. Without the morning sunlight, dew could linger on plants and cause fungal infections that lead to plant rot.
You’ll have the best results if you plant your tomatoes in an area where they will get full, natural sunlight exposure during the morning. Anything potentially blocking the morning sun from hitting your tomato plants on the east side should be removed.
If the afternoon sun provides partial sun exposure to your tomato plants, they will get enough sun exposure overall, yielding tasty tomatoes with healthy growth.
(Our tomatoes get full sun in the morning and afternoon. But later in the day, the massive red oak trees partially block the sun. The tomato plants don’t mind, and the tomato harvests are usually excellent.)
Can Tomato Plants Grow In the Shade?
You need at least eight hours of sunlight per day to grow tomatoes. So, they won’t do well in complete shade. However, some types of tomatoes can tolerate partial shade more than others. For example, some small determinate tomatoes are more shade tolerant than larger indeterminate varieties.
Tomato growth will likely slow down in the partial shade. The plants will be leggier with fewer flowers and fruits.
It’s also possible that partially sun tomatoes will be more susceptible to certain diseases since tomatoes require sunlight to help resist, dry out, and kill certain microbes and fungal pests.
Some things you can do to get better yields in the partial shade include using a trellis to support these vining plants, planting more tomatoes at once for a diverse harvest, and pruning the plants regularly so that you’re always trying to enhance photosynthesis.
Warm temperatures and well-draining soil that won’t become water-logged will give shade-grown tomatoes a better chance of succeeding.
What Tomato Varieties Are Best for Growing Tomatoes In Shade?
Planting tomatoes that are partial sun plants or that get bred to be more tolerant of shady conditions will give you the best chance for success. Here are some types of tomatoes that will do better in partial shade.
- Black cherry tomatoes
- Roma tomatoes
- Tigerella tomatoes
- Bradley tomatoes
- Red pear tomatoes
- Cherokee purple tomatoes
The hearty tomatoes above prefer high light intensity. But they can survive and produce fruit even in partial shade. They are indeterminate tomatoes, so you’ll need to offer support or consider trellising them.
Every year we grow several tomato plants along with other popular vegetables (or fruits). Tomatoes may feel tricky to cultivate at first. But after a few attempts, growing tomatoes is much easier as long as you have the time and dedication! Good soil and adequate sunlight are also keys.
So always remember, when you grow your tomatoes, they need around six to eight hours of sunlight daily.
(We’ve also read from a few reliable sources that tomatoes can get by with less sunlight – as little as four hours daily. However, we think that the more sunlight, the better.)
Thanks so much for reading.
And – if you have more questions about tomatoes and sunlight requirements, feel free to ask!
We have tons of practice growing tomatoes yearly. And we’re happy to brainstorm with fellow tomato growers.
Thanks again – and have a great day!