7 Reasons Your Tomatoes Aren’t Ripening This Season

Whether it is your first year growing tomatoes or your 10th, nothing is more frustrating than spending months pouring energy into growing healthy, productive tomato plants just to notice that the fruits are not ripening. 

Even if you have been growing tomatoes for many years, sometimes conditions just aren’t right, and tomato ripening doesn’t begin or comes to a standstill. Most of these issues are easy to fix if you prepare your soil, know what to look out for, and how to take action. 

Growing tomatoes can seem simple and straightforward, but there are a few factors that can affect proper fruit ripening. In this article, I’ll help you identify basic tomato plant needs and how to fix some of the most common tomato plant problems you might encounter. 

Energy is Being Sent to Different Parts of the Plant 

When plants become full of unnecessary foliage, empty clusters, and “suckers,” the plant has to send nutrients and water to all of these areas, spreading resources thin. This will likely create an unremarkable plant that’s unsure where to focus its energy. 

If you allow your tomatoes to form many “suckers” and grow wildly, the plant will do what it does best: reproduce. In short, this means it will create as much fruit as possible because this is the way it gets its seeds out into nature. Reproduction and spreading seeds is a plant’s main goal in life! 

Suckers grow between the main stem and each leaf, growing out of the space called the “axil.” They grow in an upward diagonal fashion, making them pretty easy to spot.

You can pinch them off with your thumb and pointer finger when they are small. Once they are thicker than a pencil, you should use tomato snips.

The Fix

You may already know this, but pruning is extremely important to the health and well-being of tomato plants for many reasons. Not only does pruning create good airflow, which decreases its chances of catching diseases and makes harvesting time easier, but it also ensures energy is being spent on 1-2 main leaders (depending on the system you choose), including ripening of the fruit.

You should scout your plants for suckers about once a week or so.  This essentially lets your plant know exactly where you want it to spend its valuable resources.

Plant is Under High Stress

During peak season, when days are hot and sunny, we often think ripening will happen more quickly since tomatoes love the heat. However, extreme heat, sun exposure and dry conditions can cause stress in both the plant and the fruit, causing ripening to come to a halt. 

The Fix

If the stress is temperature-induced, your best bet is to use shade cloth and perhaps add fans to your area to add artificial wind to cool your plants. Otherwise, it’s just a waiting game. Energy-saving mode caused by stress is a safety mechanism that kicks in to help keep the plant alive. It is spending its energy on reserving its resources to stay alive, not on ripening fruit.

If stress is caused due to drought conditions, the best thing to do is ensure consistent irrigation, with a drip line system being the best option.

This allows you to send water directly to the roots so foliage is not getting wet, no moisture is lost due to evaporation, and it supplies a steady trickle of water to each plant. You can actually purchase drip lines that feature water holes every 8-24 inches based on your plant spacing.

Lack of Lycopene and Carotene

Ideally, temperatures remain around 70-75° for tomato ripening. When it exceeds 85°+, the plant cannot produce pigment-inducing lycopene and carotene, which gives tomatoes their beautiful colors. Lycopene is used frequently in the food industry as a natural red pigment and is also very high in antioxidants.

The Fix

There is not much you can do to get a plant to create these pigments while on the vine. However, some growers pull tomatoes from the vine at “first blush” and allow them to ripen off the vine. You can do this simply by placing them on your counter or adding them to a bag to force the ripeness even quicker.

Pro Tip: Some growers tug on the bottom of the plant gently toward the end of the season. The slight shock at the root level sends a signal to the plant that it’s nearing the end, and it’s time to speed up the ripening process.

Plants are Overfertilized 

Many growers jump to “not enough food” or “not enough water” when their tomatoes are not ripening on the vine. But, many experts agree that a tomato fruit has taken in all the nutrients it needs from the mother plant by around the time the fruit is full size. 

Nitrogen, Phosphorus/Phosophate, and Potassium are the three main nutrients all plants need to survive. Tomato plants have different nutrient requirements at different growth stages. 

Pro Tip: It’s important to always test your soil prior to planning your garden so you know what you’re working with and make informed decisions about when and what to feed your plants. For instance, if your soil is high in nitrogen, you should not use a fertilizer high in nitrogen because you could risk burning your plants. 

The Fix

Here are a few notes regarding the “Big 3” when it comes to growing tomatoes.

Improper Watering

Tomato plants should be watered regularly. To combat under or over-watering from the start, be sure to have well-draining and compost-rich soil. This will help with nutrient uptake, root development, and retaining moisture content while growing. 

Tomato fruits often won’t ripen when they are overwatered by overzealous gardeners or are underwatered due to neglect. Improper watering is one of the primary causes of many tomato problems, including a lack of mature fruit.

The Fix

Have a good irrigation system in place that supplies plants with consistent and regular moisture. Tomato plants need about an inch of water per week, so if you are not receiving enough rain, you should irrigate!

You should slightly increase watering just before your tomatoes start to change color to boost the amount of moisture within each fruit. This will result in juicy mature fruit.

You can decrease your watering just after you notice your tomatoes starting to change color. This is because the amount of moisture within each fruit will not change after that point. Each time you water your plants, ensure a nice thorough soaking.

Watering after your fruits begin to mature is done to help keep plants healthy and able to support the weight of all the maturing fruit.

Sunscald (Too Much Sun)

Most of us know that the foliage of plants exists to intake sun and aid in photosynthesis. However, they also provide vulnerable fruit coverage from the sun. Too much direct sunlight can damage fruits, causing them to develop a blotchy or discolored appearance.

Fruits can also heat up to temperatures not conducive to ripening and send the plant into energy-saving mode! This is referred to as tomato sunscald, and it’s a common tomato plant problem.

The Fix

Be sure that when pruning, you start at the bottom, removing leaves from above empty trellises. Their job as fruit protectors is done once you have harvested the lower fruit.

Plus, removing lower leaves opens up the plant for additional airflow, and keeping low-hanging leaves off the ground decreases their chance of contracting some fungal diseases.

You can also use a popular gardening technique called grafting, which can help combat sunscald and is outlined in the video below.

As you move up the plant, keep leaves intact that are serving as a canopy for still-ripening fruit.

Your Geographic Region

In many cooler regions, growers use greenhouses or heat to extend their tomato growing season because the summers are so short.

Here in New Hampshire, daytime temperatures can get into the 70s or 80s as early as May, but the nighttime lows slow warm weather crops down. We always plant our tomatoes in a protected tunnel and use row cover at night to keep them above 50°. 

If it gets to late summer and your tomatoes are still sending energy into newly pollinated flowers or growing vertically, it may be time to, well, nip in the bud, quite literally. Keep reading to see what I mean. 

The Fix

If you are nearing the end of the season and temperatures are cooling down, you may want to consider snipping off the top of your tomato plant. This is called “topping.” This will force energy into the ripening of fruit instead of continuing upward growth.

Begin to cover your plants at night as you did in the spring if nighttime temps start to dip below 50°. Otherwise, ripening could begin to slow down due to cold-induced stress.

You can also communicate with your tomato plant where you’d like it to send its energy by pinching off any young flowers and undeveloped fruit. This will cause the plant to send energy into any full-size fruit waiting to turn red.

You can also select short-season or early-season tomatoes when selecting seeds. Early Girl and Fourth of July are slicer options that take around just 50 days to mature. Sweetie and Washington Cherry are good cherry tomato options.

Pro Tip: In general, cherry tomatoes ripen more quickly than slicers, beefsteaks, and sauce tomatoes, simply due to their size, so you can select those if you live in a cooler region with a short season. You can also get a head start on all tomato plants by starting them indoors under grow lights or purchasing established plants from a trusted supplier.