If more than one plant comes up in a single tray compartment, I take my tiny sewing scissors and cut two of the three. If you try to pull the other two out, you run the risk of damaging the roots of the plant you want to keep.
When your plants have three sets of leaves, it’s time to transplant them. It took five weeks from the day I planted the seeds for the plants to get to transplant height.
We’re still two months from our last frost date so these plants are going into one cup sized peat pots. I write right on the pots with a sharpie. These are brandywine tomatoes (BW). I’m also experimenting this year with wooden swizzle stick plant markers. I’m writing on those and sealing my writing with clear nail polish. We’ll see how it goes.
Before you try to remove them from their compartment cells, water thoroughly. This will hold the roots in the potting medium and make the plant easy to remove. I use a fork to remove the plant from the cell and place it into the peat pot. Never touch the stem of a plant, just the dirt and leaves if you must. For tomatoes, it’s important to plant them as deep as possible. The stems will grow more roots and improve the stability of your plants. I fill the pot with a 50/50 mixture of seed starting mix and potting soil with a few Soil Moist crystals thrown in to help maintain moisture. They’re hard to find and expensive but we use them. I’ve found them both online and in a very upscale garden center (not near here!).
It’s very satisfying to grow your own food. Go ahead and give this a try, you know you want to!