Does a decreasing day length affect blossom set and ripening?

dfollett · September 7, 2013

I know that the length of day – and changes in the day-length – have a tremendous effect on much of the animal kingdom. I assume it drives much of the plant life, although I don’t have any direct knowledge of that. For example, by using artificial light and increasing the day-length, you can get a mink to breed in the fall instead of spring (they breed only once a year). Or, by decreasing the day-length, you can get them to put on their winter fur coat in the summer, in spite of the temperature (albeit, not as luxuriously).

Does the decreasing day-length in the late summer and fall cause a tomato plant to speed up the setting of blossoms or ripening process?

The reason I ask is:

I am trying to grow a fall crop for the first time. When I start seedlings for spring planting, I do it under artificial light with a constant day-length (timer). I started seedlings for this crop in a southern-exposed window. I augmented with artificial light, but it was on less than the full day. The plants were exposed to the natural day-length which, at that time, was getting shorter each day. I set these seedlings out earlier than those I started in the spring, but there were many more blossoms already in place (at 6-7 weeks) than on the ones I started in the spring. About 20% of the seedlings had mega-blooms on them and I don’t recall seeing any of those on the plants I set out in the spring. Is there a correlation?

Also, is there any chance that the decreasing day-length will encourage a shorter DTM than those planted in the spring when they experience an ever increasing day-length? They will get more light as small plants and less light as mature plants.

September 7, 2013	#1
dfollett Tomatovillian™ Join Date: Dec 2012 Location: Utah Posts: 693	Does a decreasing day length affect blossom set and ripening? I know that the length of day – and changes in the day-length – have a tremendous effect on much of the animal kingdom. I assume it drives much of the plant life, although I don’t have any direct knowledge of that. For example, by using artificial light and increasing the day-length, you can get a mink to breed in the fall instead of spring (they breed only once a year). Or, by decreasing the day-length, you can get them to put on their winter fur coat in the summer, in spite of the temperature (albeit, not as luxuriously). Does the decreasing day-length in the late summer and fall cause a tomato plant to speed up the setting of blossoms or ripening process? The reason I ask is: I am trying to grow a fall crop for the first time. When I start seedlings for spring planting, I do it under artificial light with a constant day-length (timer). I started seedlings for this crop in a southern-exposed window. I augmented with artificial light, but it was on less than the full day. The plants were exposed to the natural day-length which, at that time, was getting shorter each day. I set these seedlings out earlier than those I started in the spring, but there were many more blossoms already in place (at 6-7 weeks) than on the ones I started in the spring. About 20% of the seedlings had mega-blooms on them and I don’t recall seeing any of those on the plants I set out in the spring. Is there a correlation? Also, is there any chance that the decreasing day-length will encourage a shorter DTM than those planted in the spring when they experience an ever increasing day-length? They will get more light as small plants and less light as mature plants.