It seems my leaves are small, like about a half inch in length. I am growing Iglehart Yellow Cherry tomatoes. Thank you.
I'm guessing they are still inside. It's too chilly still for them to be outside. Try giving them more light. You also might try putting them back on the heat mat since they like it warm. Here are best practices that may help:
https://www.gardeningknowhow.com/edible/vegetables/tomato/growing-cherry-tomatoes.htm
https://www.gardeningknowhow.com/edible/vegetables/tomato/yellow-tomatoes.htm
https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-fertilizer.htm
https://www.gardeningknowhow.com/edible/vegetables/tomato/growing-tomatoes-from-seed.htm
How often should one open the polytunnel when seedlings are growing.
Plant the tomatoes the same distance you would without the polytunnel. Space them depending on the variety size. If you are only starting them in the tunnel and will move them out when the weather warms, you can plant them much closer. On warm days, you will need to ventilate the tunnels so the plants do not overheat.
https://extension.wvu.edu/lawn-gardening-pests/gardening/gardening-101/low-tunnels-for-beginners
You stated in your "ripening tomatoes on vs off the vine" article that the fruit is essentially sealed off from the vine at the breaker stage. So how does it get water?
They don't need water to continue to ripen. If you harvest the tomatoes at the breaker stage, they can be stored or set on the countertop to ripen.
https://www.gardeningknowhow.com/edible/vegetables/tomato/are-vine-ripened-tomatoes-better.htm
Hi:) All my tomato seedlings have turned whitish please see picture below. Could you guide me in the right direction? Thank you!
It could be they are getting too much light too quickly such as moving them outdoors without hardening off or it could be disease. This article should help:
https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-leaves-turn-white.htm
I have two beautiful healthy Florida 91 F1 PL Tomato plants, both have a great many blossoms. One has several small tomatoes formed, but the other has even more flowers but not fruit. Should I give it potassium? Something else? Thank you for you help
It could be a pollination problem rather than a chemical imbalance. If you are following a fertilization program already, it could be detrimental to add too much. These articles should help:
https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-blossoms-no-tomatoes.htm
https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-fertilizer.htm
No there's no additional detail
It could be herbicide injury. This article should help: