Updated June 2025

People are understandably disappointed when the plants they’ve carefully tended and nurtured fail to produce the bountiful crop they dreamed about all winter. Growing tomatoes in the north can be tricky for one main reason: our uniquely humid midsummer climate.

The month of July in most northern climates is notable for extended periods of scorching hot and unbearably humid weather. When you see records broken for the highest dew point ever recorded, know that your tomatoes are likely unhappy. Unfortunately, as we all know, there’s not much gardeners can do about the weather.

Pollination Problems with Tomatoes

Tomato plants rely on their pollen to be shaken loose from the anthers in the flower—either  through the action of the wind or a pollinator like a bee—so that it lands on the stigma and pollinates it. When the temperature rises above 90 degrees with high humidity, the pollen becomes sticky and won’t shake loose. The result: in a long spell of excessively hot and humid weather an entire bloom cycle can be lost, with little or no fruit being set.

So, how can gardeners react? You could help your tomatoes pollinate by shaking the plants yourself or using a gently vibrating toothbrush. Remember: If you are growing a plant start from a garden center, you’ll likely have a hybrid type rather than heirloom. These are much easier to handle regarding pollination. If you do own heirlooms, you may need to apply pollen to each flower by hand with a Q-tip.

Choosing the Right Tomato for Your Space

Tomatoes have two types of growth habits; determinate plants, where the flowers all bloom at the end of the stems, so the fruit sets all at one time and then is finished, and indeterminate types, which continue to grow more stems and flowers and set fruit until a killing frost takes out the plant. Determinate plants tend to be smaller and more compact bush forms, and indeterminate varieties have trailing vines that should be staked or even pruned in some cases. When selecting a tomato plant, read the tag to see which type it is.

Selecting the Best Spot to Grow Your Tomato Plants

Once you’ve bought your tomato, you can plant it in a container or in the ground or a raised bed, but the process is much the same. If it’s early in the season, take a look at the long-range weather forecast to see if there’s any chance of frost. Tomatoes are tender plants, and even a nipping frost can set them back. If it appears that frost is imminent you could cover the plants or even move them to a sheltered spot if they’re in pots, but it’s best to wait until the coast is clear before planting so you don’t have to think about it. Besides, tomatoes planted outdoors before the soil warms up aren’t going to do much anyway.

Choose a sunny spot where your tomato will receive at least seven hours of direct sunlight. Any less than that and the plant will produce a lot of foliage and little fruit. If you’re planting in a container, choose the largest one you can manage—tomatoes develop extensive root structures that need room.

Similarly, if you’re planting in the ground or in a raised bed, prepare a planting hole that’s significantly larger than the pot the tomato is growing in. You want to create an optimal growing medium for the tomato, so in a container that means a good quality planting mix that loosely fills the container—you don’t want to pack it in.

If you’re planting in average garden soil, add compost to the mix. In either case, tomatoes benefit from a balanced fertilizer—look for those sold as tomato formulas—and include it at the ratio recommended on the package.  At this point, some people might add other amendments like calcium to the soil—more on that in the next post.

Plant your tomato deep; you can bury it right up to the top leaves and it will develop roots all along the stem. Then water it in well—I give each plant at least a gallon. Set your tomatoes up for success now and you should be able to weather any storm (or excessive humidity) that comes your way this year.