Last year I started cherry type tomatoes under lights then enjoyed a bumper crop after moving the plants to a large container on my balcony. This year I started plants under the lights again using seed saved from last year’s crop, and moved them to the same container after the last frost date. The plants look healthy and seem to be growing normally, but they are flowering already and the flowers are so small that any fruit which develop are likely to be only a little larger than a pin head. Do you have any suggestions on how to get the flowers and subsequent fruit to be normal size for a cherry tomato? In anticipation, thanks for your answer.
Thank you for contacting the Toronto Master Gardeners regarding your early flowering tomato plants. Your plants may be flowering a bit prematurely and it sounds like the blossoms are unusually small. When flowering, plants are putting most of their energy into developing blossoms and not other forms of growth (root development, leaves, etc). It is still early enough in the season that you could try sniping / pinching the plants (flowers) back. As long as you can leave at least 2-3 sets of leaves on the plant, there is enough time for the plant to continue growing and develop new flowers and fruit. You mention that you are using the same pot as last year. Are you using the same soil? You may also want to consider a light dose of a tomato fertilizer (has less nitrogen) or organic fertilizer such as a fish emulsion or kelp-based fertilizer. Soil in pots may become nutrient depleted over time. With adequate water and light it is most likely that your tomatoes will thrive.
Although not entirely specific to your situation, I have attached a link to general information about pruning tomatoes for further reading.
Best of luck with your balcony garden.