Brawley Seed Co. · Garden Journal

Why Your Tomatoes Won't Turn Red (When They're Already Full Grown)

You've got a tomato the size of a fist, hanging there full and green, and it has been for what feels like forever. You're waiting on red and it's just not coming. We are all in the same boat, its happening in my garden too. Same villain as before: the heat.

It's the heat again

A tomato turns red because it's making a pigment called lycopene, and here's the catch, that pigment production shuts down once it gets above about 85 to 90 degrees. So in a stretch like the one we just had and are currently in, a mature tomato will sit there stubbornly green, not because it isn't ready, but because it's too hot for it to color up.

The fix is easy, and it helps your plant

The fix is easier than you'd think, and it actually helps your plant. Pick the tomato at what we call the breaker stage, that first faint blush of color at the bottom. Bring it inside and let it ripen on the counter, out of direct sun. And no, not on the windowsill, that's an old wives' tale that mostly just cooks and rots them. On a shaded counter it'll redden up in a few days, sweet as anything. Pulling that fruit early also takes the load off your plant so it can set and ripen the next ones, we love to see more production.

And when it cools, the vine takes over again

Once our nights cool down, on-the-vine ripening kicks right back in.  We don't want to hear how you just ripped your tomato plant out because your tomatoes weren't turning red. Patience and a shaded kitchen counter is all you need!