: :Hi. : :I have several tomato plants in the greenhouse, Gardeners Delight, :Shirley F1 and Striped Roman. : :My liquid tomato food says to start feeding once the first truss has :set. What exactly does "set" mean ? - Gone red ? Flower died off ? and :does it mean the whole truss or just the first tomato ? : :Thanks -Dave.
Your tomato has set when you see the tiny green tomato in lieu of the flower. The first tomatos often don't set because nighttime temperatures are too cold (if they drop much below 55 F). To make the first ones set I always apply tomato setting hormone, which you can get at your garden supply. It's a spray, but I always apply with a soft little brush, personally, and have been using my spray bottle (sprayed into the plastic bottle cap, which I dip my brush in) for many years (double digits).
When to fertilize is totally individual depending on the nature of your planting soil. Myself, I fertilized earlier this year than I normally do, which is when the first tomatos are golf ball sized, and I think I over fertilized, because the plants are twisting like corkscrews. I'm going to hold off on more fertilizer for quite a while. In fact, I think I worked enough compost into the soil that I could get a very respectible crop with no more fertilizer. I'll see how things go.
Dan