Congratulations! It’s your first year growing tomatoes in a greenhouse. You’re in for a treat—extended harvests, faster growth, and plants protected from unpredictable weather. Hurrah!.
This post builds on a previous one where I talked about crop rotation, which is especially important for nightshades like tomatoes when growing in the ground in a greenhouse.
We will talk about 8 more common mistakes gardeners make when growing tomatoes in a greenhouse that can hurt their crops in this guide.
Growing tomatoes in a greenhouse provides many benefits, like extending the growing season and protecting plants from unpredictable weather. However, greenhouse conditions can also lead to some unique challenges for tomato growers.
In this article, we’ll explore 9 of the most common tomato problems that crop up when growing in a greenhouse environment We’ll also provide tips to prevent and treat these issues, so you can reap a bountiful greenhouse tomato harvest
1. Poor Air Circulation Leads to Fungal Diseases
The enclosed space of a greenhouse means less air movement around plants This humid, still air encourages fungal diseases like early blight, late blight, and powdery mildew to take hold
You’ll notice yellowing leaves with white powdery spots, drooping foliage, and a musty odor. To improve air flow, install ventilation fans and open doors on warm days. Prune lower leaves to allow better air circulation.
2. Low Ceilings Cause Trellising Issues
Indeterminate tomato varieties can grow quite tall and will outgrow short greenhouse ceilings. This makes trellising difficult, leading to collapsed and tangled plants.
Opt for determinate or dwarf varieties with a more compact shape. Try horizontal trellising. Prune regularly to control height.
3. Lack of Rainfall Results in Dry Soil
One downside of greenhouse growing is no natural rainfall. This means diligently monitoring soil moisture and watering frequently to prevent drought stress.
Signs of too little water include wilting, curling leaves, and uneven moisture in soil. Install drip irrigation, use mulch to retain moisture, and check soil often.
4. Overhead Watering Spreads Disease
Unfortunately, greenhouses often rely on top-down watering methods since there’s no rain. This splashes soil onto leaves and spreads blights, fungi, and bacteria like spot and speck.
Switch to drip irrigation to target roots. If using a hose, aim water at soil level and water early in the day so leaves dry quickly.
5. Overcrowded Plants Become Stressed
It’s tempting to cram in more tomato plants to maximize limited greenhouse space. However, overcrowded tomatoes compete for light, water, and nutrients, stunting their growth.
Follow spacing guidelines and allow at least 18 inches between plants. Prune regularly to improve light and air penetration to lower leaves.
6. Tight Spaces Make Pruning Difficult
Lush growth and confined quarters can make pruning greenhouse tomatoes a chore. But pruning is vital to plant health, and neglected plants become overgrown and prone to disease.
Stay on top of suckering and pruning lower leaves. Use the right tools for the tight space. Train and trellis plants from the start to direct growth.
7. Lack of Crop Rotation Depletes Soil
Growing tomatoes in the same greenhouse soil year after year depletes nutrients and organic matter. This leads to reduced yields and vigor.
Incorporate cover crops like hairy vetch during off seasons to boost nutrition and reduce disease. Rotate tomatoes to different beds each year.
8. High Temperatures and Heat Stress
Greenhouses easily overheat on hot sunny days. This heat stress causes blossom drop, poor fruit set, and lower yields.
Use shade cloth and open vents to cool the greenhouse. Water in mornings or evening to help plants cope with heat.
9. Pest Pressures
The enclosed space also makes greenhouse tomatoes more susceptible to pests like aphids, whiteflies, and spider mites that thrive in warm environments.
Regularly check for signs of pests like sticky leaves or webbing. Release beneficial insects and practice preventive sprays like neem oil. Remove heavily infested plants.
While greenhouse tomato growing has its challenges, paying close attention to preventive care and pest monitoring will allow you to get the most out of your protected growing space.
Implementing ventilation, pruning, and soil improvements will help you avoid the most common pitfalls and realize the benefits of extended harvests and protection from the elements.
Poor Airflow: Leads to Fungal Issues
A sad tomato who has succumbed to late blight. RIP buddy. Photo CC0 Scot Nelson
Poor airflow in your greenhouse can create a humid environment. The sides are covered, so the tomatoes are safe from most weather. Plus, the wind that plants get outside is good for them.
This lack of wind is the perfect breeding ground for fungal diseases like powdery mildew and blight. These diseases can be devastating to the health and yield of your tomato plants.
Here’s What to Look For:
- Yellowing leaves with white, powdery spots.
- Leaves curling or drooping for no apparent reason.
- A musty smell in your greenhouse.
Here’s How to Solve It:
- Install Ventilation Fans: Ensure there is consistent air movement. This will reduce the risk of fungal diseases.
- Open Windows and Doors: On warm days, increase natural airflow.
- Cut off the lower leaves. This lets air flow around the plants’ bases, which lowers the humidity. It’s like giving your plants room to breathe.
Low Ceilings: Causes Trellising Problems
Indeterminant tomatoes will usually outgrow the low ceilings of a greenhouse and cause trellising issues
Tomato plants, especially indeterminate varieties, can grow quite tall. Low ceilings limits your trellising options. It might be tempting to let them spread out, but they’ll get tangled up and be hard to control soon.
Here’s What to Look For:
- Tomato plants bending or collapsing under their own weight.
- Trellising structures hitting the ceiling.
- Reduced plant vitality due to lack of vertical space.
Here’s How to Solve It:
- Use Shorter Varieties: Go for determinate or dwarf tomato varieties.
- Adjust Trellising Techniques: Use horizontal trellising to guide the plants. Getting a vine to grow along a fence is one way to do this.
- Regular Pruning: To keep the plants more compact, look for pruning times a couple of times a week.
Top 5 Problems You Could Have When Growing Tomatoes
FAQ
What are the disadvantages of growing tomatoes in a greenhouse?
Do tomatoes grow well in greenhouses?
How hot is too hot for tomatoes in the greenhouse?
Why are my tomatoes dying in my greenhouse?
Can Tomato plants grow in a greenhouse?
Tomato plants are one of the top plants that greenhouse growers choose to grow inside of a greenhouse. The warm and protected climate makes for a perfect tomato-growing environment. Unfortunately, tomato plants aren’t the only thing that thrive in a greenhouse. Tomato pests and diseases can get inside and threaten the health of your tomato crop.
What do gardeners miss when growing tomatoes in a greenhouse?
In this guide, we’ll look at 8 other common things gardeners miss when growing tomatoes in a greenhouse that can hinder their harvests. Let’s get to it. Poor Airflow: Leads to fungal issues. Low Ceilings: Causes trellising problems. No Rainwater: Lacks a natural water source. Overhead Watering: Encourages soil-borne diseases.
What causes a tomato plant to die?
Diseases, fungi, and certain environmental conditions can quickly cripple your plants. Oftentimes, you can rescue the tomato plant with a little TLC, but some circumstances may require you to destroy it and plant another crop in its place. Here are the most common disease and fungus triggers in tomato plants:
Do tomato plants have pests?
For the most part, greenhouse tomato plants are protected from inclement weather and large pests. Smaller pests and diseases, however, can get inside and infest your tomato plants. Fortunately, monitoring your plants for signs of pests and diseases will help you manage the problem before it’s too late.
Why are my tomato plants not growing?
It is also important to ensure magnesium is present, as this affects the plant availability of calcium. Remineralization with a product like Azomite can be beneficial. Most notably, consistent moisture ensures that tomato plants can uptake these minerals. Avoid huge fluctuations from dry to wet roots. Why Aren’t My Plants Growing?
What are some common tomato problems?
Leaf curl or leaf roll is another common tomato problem you are likely to encounter. This condition worries many new gardners, but take heart in the knowledge that there is usually no cause for alarm. Most causes of tomato leaf curl are stress related.