Tomato shortage likely caused by hot days, cool nights

It is nearly the end of August and we should be awash in tomatoes from

It is nearly the end of August and we should be awash in tomatoes from the garden or the farmers market right now. 

This time of year, we should have eaten every type of tomato dish we could think of by now. Every backyard picnic table should be unsuitable for picnicking right now because they should be covered edge to edge with red, yellow and purple tomatoes. 

But this is not the case this growing season as tomatoes have been very slow to set fruit and ripen. And it’s not just backyard gardeners who are suffering from a shortage of tomatoes, as farmers who sell at area farmers markets are also reporting slow ripening of tomatoes and reduced yields.

There could be several reasons for slow ripening of tomatoes, but the primary culprit is likely the variable weather that we have experienced this growing season, specifically air temperatures.

Mike Hogan

Know your varieties

Every tomato variety has a specific number of days to maturity — when tomatoes are ripe and ready for picking. Larger-sized tomatoes tend be longer season varieties, while varieties with smaller fruit, such as cherry tomatoes, tend to ripen more quickly. 

Most varieties ripen six to eight weeks after flowering and pollination. It is normal for most varieties that producer larger fruit to take longer to ripen. If you have forgotten the maturity dates for the varieties that you planted, check the seed packet, seed catalog or plant tag to determine when you can expect the majority of your tomatoes to ripen under typical circumstances.

Tomatoes typically ripen 6 to 8 weeks after flowering and pollination.

Heat-loving to a point

Tomatoes are heat-loving plants, which is why we never want to get too excited about getting them transplanted out in the garden too early in the season. Especially in their young vegetative stage, tomatoes thrive on warm air temperatures and soil temperatures. When these plants begin to flower and set fruit, excessively hot air temperatures can cause flowers to drop before fruit begins to set, reducing the number of tomatoes produced and delaying harvest.

Smaller sized tomatoes tend to mature and ripen sooner than larger varieties.

Mild temperatures required for ripening

Once tomatoes have grown to their mature fruit size and start to turn from dark green to a lighter green and cream color, the ideal air temperature range for ripening is 68 degrees to 77 degrees. When air temperatures rise above 85 degrees to 90 degrees, the ripening process slows significantly and can even stop. At these temperatures, lycopene and carotene, pigments responsible for giving tomatoes their typical orange- to red color cannot be produced. As a result, the fruit can stay in a mature green phase for a long period.