By now our tomato plants should be getting pretty well established and maybe you have even been getting tomatoes, but environmentally issues may be affecting your tomato plant’s production. Here’s a few things to be aware of and what you can do about some of them.

Heat has a big effect on our tomato plants. Each year (usually a little later in the year) we get calls from people saying that their tomato plant is producing flowers but no tomatoes. This is an issue we call “blossom drop.”

Blossom drop occurs as we start getting daytime temperatures above 90 degrees. Heat above 90 degrees can work against proper pollination, causing the un-pollinated flowers to drop off. This temperature issue also works the other way in that pollination can also be inhibited when we have nighttime temperatures cooler that 55 degrees. Not much chance of that right now, but we had those and will have them again this fall.

So, if you are getting flowers on your tomato plants, but no tomatoes, this is likely the problem. Plants may continue to produce some tomatoes, but not nearly at the level as they would when the temperatures were in their comfort zone. Our goal during the hottest days of summer is to keep the plants alive until it cools down a bit.

Another challenge tomato growers have likely faced recently is something called “blossom-end rot.” Blossom-end rot causes the blossom-end of your tomatoes (the part opposite the stem) to turn brown. This brown area can expand and start to feel a bit leathery. When this occurs, the fruit is more susceptible to disease.

While blossom-end rot is ultimately caused by a lack of calcium, odds are you don’t have a lack of calcium in your soil. Calcium is considered a micro-nutrient, and it doesn’t take much to have healthy fruit on your plants. Online many will see a variety of cures for blossom-end rot. Some of these include adding tums to the soil or even Epsom salts. Neither of these will help because blossom end rot is primarily caused by water inconsistency. Because of this, we tend to see blossom-end rot after a period of excessive rain which leaves the soil soaked followed by periods of dry soil. This irregular water availability inhibits the uptake of calcium, which can cause blossom-end rot. For the most part, this condition tends to work itself out, but it underscores the need for consistent watering of our tomato plants.

Catfacing is another interesting environmental problem and occurs when the plant is flowering, and we have temperatures below 58 degrees. We could use some of that weather right about now. But, during these colder temperatures, the flower doesn’t develop properly. It can still be fertilized but there’s a chance for some imperfections in the fruit known as catfacing.

In addition, an herbicide called 2,4-D used to kill weeds can also contribute to catfacing in tomatoes. This herbicide doesn’t need to be used directly on the tomato plants, but instead, it can vaporize and drift from the applied location onto your tomato plants. Tomato plants that produce larger tomatoes tend to have more problems with catfacing.

The good news with all these environmental problems is that they eventually seem to work themselves out. Just water regularly and remain mindful of how lucky we are to be able to grow anything at all. Good luck.

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701 or by emailing us at mg@tulsamastergardeners.org.