As the weather warms up, you may be thinking about planting your tomatoes. But before you do, it’s a good idea to learn about the dangers of late spring frosts. Frost can damage young tomato plants, causing them to produce less fruit. Keep an eye out for these three signs of frost damage so you can take action to protect your plants.
When I first started gardening, I planted tomatoes way earlier than recommended for my area. I was so excited to get my tomato plants out in my yard that I began hardening off my seedlings several weeks early. As a result, I stunted my tomato plants because they were exposed to cold temperatures. Thankfully, they made a comeback, and I ended up with a decent harvest, but I learned from my mistake and have enjoyed even better yields in the following years.
This article will discuss three signs of frost damage in young tomato plants. We’ll also provide tips on how to protect your plants from further damage. So if you’re worried about frost damage this season, read on for helpful information.
What is frost damage, and why is it a problem for tomato plants?
Frost damage is a significant problem for tomato plants. When the temperature falls below freezing, the water in the plant cells freezes and expands. This can cause the cell walls to rupture, resulting in frost damage.
The frost also damages the plant’s leaves, stems, and flowers, making it more difficult for the plant to photosynthesise and reproduce. Frost damage also reduces the tomato plant’s ability to take up nutrients and water from the soil.
As a result, frost-damaged plants are less productive and more susceptible to disease. In severe cases, frost damage can kill a plant outright. For this reason, it is essential to take steps to prevent frost damage on tomato plants.
Identifying signs of frost damage in young tomato plants
One of the most frustrating things that can happen to gardeners is frost damage on their tomato plants. Not only does it mean lost fruit, it can also set your plants back for the rest of the season.
However, frost damage is not always easy to spot, especially in young plants. Here are some common signs to look for:
1. Wilted or drooping leaves
This is one of the most apparent signs of frost damage. Leaves will turn brown and curl up at the edges, and the plant may droop down as if it is wilting.
2. Yellow, brown, or black-speckled leaves
Another common symptom of frost damage is blackened or browned leaves. This can happen when the frost burns the leaves, causing them to turn dark and papery.
Sometimes, this damage presents as brown or yellowish speckles on the leaves and stems. These are called “frost spots,” and they are caused by the plant’s cells being ruptured by the expanding ice.
3. Stem damage
If the frost damage has travelled all the way down to the bottom leaves of the plant and the stem, you might have a severe case of irreversible damage. However, if you planted your tomato plants deeply, your plant may still recover after a few weeks.
Look out for new, green growth at the base of the plant within a couple of weeks. If new growth doesn’t appear, the plant likely won’t recover, and it’s best to transplant new seedlings.
How to avoid frost damage for your tomato plants in spring
You’d think that protecting tomato plants from frost is a reasonably simple task. Just don’t put them outside when it’s freezing! Right?
Not entirely. It turns out that there are several factors to keep in mind when trying to avoid frost damage on your tomato plants.
Don’t plant tomato seeds too early
Avoid planting tomato seeds too early in the year, and you’ll easily be able to avoid frost damage on your tomato plants. Often, beginner gardeners rush to get a jump start on the gardening season by planting their seeds early.
In some cases, gardeners can continuously pot up their tomato plants and take care of them indoors until the weather is suitable for transplanting. But in most cases, tomatoes planted earlier than recommended will grow out of their seed trays. Gardeners won’t have enough space to accommodate them indoors, so they get put outside before the cold weather subsides.
By waiting until the recommended tomato planting window arrives, you’ll be much more likely to help your plants avoid frost exposure. For tomatoes, this is usually 6-8 weeks before your area’s last frost date, but recommendations vary depending on the type of tomato you’re growing.
Plant tomatoes deep
Tomatoes and other nightshade family plants can be planted deeper than other plants. Each of the tiny hairs on a tomato plant’s stem has the potential to become a new root! One benefit of planting tomatoes deep is that the root systems will be stronger and better protected from cold weather.
To plant tomatoes deeply, remove the bottom leaves and branches on seedlings, leaving just a few sets of leaves above the ground. The tomato plant will build a robust root system deep in the soil, which will help insulate the roots against the cold. Deep planting has other benefits, too. For example, better access to nutrients in the ground, which leads to better-tasting tomatoes and possibly more prolific yields!
Protect them physically
Adding a layer of frost protection to help insulate your plants from cold or nippy weather is an effective way to keep them warm.
One way to do this is to cover the plants with a frost cloth or tarp when cold weather is forecasted. These thick fabric barriers do a great job of keeping your tomato plants cosy during a volatile spring.
You can use old blankets or sheets for the same purpose. Another method is to use row covers or cold frames to create a micro climate around the plants warmer than the surrounding air. Milk jugs, juice containers, and soda bottles cut in half with several small holes for airflow are other common ways to protect young plants outdoors.
Harden them off
Tomato plants that have been started indoors need to be “hardened off” before being transplanted outdoors. Hardening off is the process of slowly acclimating indoor plants to the harsher conditions outdoors, like wind, sun, and temperature fluctuations.
Harden off your tomato plants by placing them outside in a sheltered spot for a few hours each day, gradually increasing the time they spend outdoors over a week or two. Being patient and sticking to a deliberately slow hardening off schedule will give them time to adjust to new conditions and reduce the risk of transplant shock.
Nutrients in seed starting mixes only last for a few weeks! So while your tomato plants are still indoors, give them a dose of organic fertiliser about once per week. The fertiliser should have nitrogen and potassium available, and it’s best to feed them with a water-soluble fertiliser so those nutrients will be immediately available to the seedlings.
Once your tomato plants have been hardened off and are ready to be transplanted, prepare the tomato planting hole with care and give them a final dose of fertiliser before planting them in their permanent outdoor home.
A well-balanced fertiliser regimen will help your tomato plants thrive and produce bountiful fruit despite the challenges posed by the weather.
Water them well
Watering your plants well before a frost is another way to prevent damage. Moisture in the soil helps moderate the temperature and protect roots from the cold.
Be sure not to water too close to the stems or leaves, as this can encourage fungal growth. Watering your tomato plants in the morning allows them to dry out before nightfall.
How to protect your frost-damaged tomato plants from further damage
Frost damage on tomato plants can be unsightly and discouraging, but it doesn’t have to be the end of your gardening season. You can help your plants recover from frost damage and prevent further damage with some care.
Here are a few tips:
- Avoid immediately trimming frost-damaged leaves or stems. These leaves might not recover, but the plants are already stressed, and trimming them off would only exacerbate this issue.
- Quickly give them some water-soluble fertiliser to help the plants recover quicker by giving it some much-needed nutrients.
- Be diligent about protecting the plant from the elements. Cover the plants with a blanket or row cover if more cold weather is forecasted. Even if the temperatures aren’t below freezing, covering your plants can help regulate them. Tomatoes are warm-weather crops, after all!
- Move them indoors. If all else fails, and you know a hard frost is on the way, you can try moving your tomato plants indoors. This isn’t always practical, but it’s worth a shot if you have the space. Just be sure to gradually acclimate them to indoor conditions so they don’t go into further shock.
- Replant more tomatoes. Sometimes, you have to cut your losses and start again. If the frost damage appears to be greatly stunting your plants early in the gardening season, you probably still have time to plant new tomatoes in time for a harvest. Look at fast-growing tomato varieties if you have less than 70 days left in your growing season.
Preventing frost damage in your garden in autumn
As the weather cools in autumn, gardeners should take special care to prevent frost damage on their plants. Tomato plants are one of the most frost-sensitive crops and can sustain damage at temperatures of 13C (55F) or below.
To prevent frost damage, gardeners should water their plants thoroughly at least 24 hours before a frost is expected. Using frost covers or blankets to keep the plants warm, planting tomatoes deeply, and mulching are other ways to protect them. By taking these precautions, gardeners can help their plants survive the chilly autumn months and extend their gardening season.
FAQ about Frost Damage and Tomato Plants
What temperature does it need to be for frost damage to occur on tomato plants?
Frost damage can occur at temperatures below 13 C (55 F). Therefore, it’s best to wait until daytime and nighttime temperatures exceed this threshold before transplanting tomatoes outdoors.
What are some signs of frost damage on tomato plants?
Some signs of frost damage on tomato plants include drooping leaves, blackened stems, damaged stems, and brown patches on the leaves.
How can I prevent frost damage on my tomato plants?
You can do a few things to prevent frost damage on your tomato plants. Water them well before a frost is expected, use frost covers or blankets to keep them warm, and give them a dose of water-soluble fertilizer.
What is the ideal temperature to transplant tomato seedlings outdoors?
Tomato seedlings should be transplanted outdoors when the weather is warm, ideally above 55-60 degrees Fahrenheit (13-15.5 degrees Celsius) If it’s still cool outside, wait a few weeks and transplant them when the weather warms up.
I think my tomato plants have frost damage. What should I do?
If your tomato plants have frost damage, cover the plants with a blanket or row cover if more cold weather is forecasted, and be diligent about protecting them from the elements. You can also try moving them indoors if it’s not too late in the season. Lastly, you can replant more tomatoes if the damage is bad enough.
Tomato plants are one of the most frost-sensitive crops and can sustain damage quickly during cold weather. Watering thoroughly, using frost covers or blankets to keep the plants warm, and removing any frost-damaged leaves as soon as possible are all ways to mitigate frost damage on tomato plants.
By taking these precautions, gardeners can help their plants thrive in springtime and survive the chilly autumn months to extend their gardening season.
What tomato planting mistakes have you made before? Have you been able to help your tomato plants recover from frost damage? Let me know in the comments, and let’s start a discussion. Happy gardening!