How to keep warm season veggie starts warm

Asked March 26, 2020, 1:54 AM EDT

For the first time this year I decided to start warm season veggies (tomatoes, eggplant, zucchs, melons) from seed rather than buying starts. They've all just about sprouted after staying nice and warm in my oven. I'm trying to figure out what to do next. I have a cold frame outside that sits on the ground and is built from lumber and topped with an old window. It's pretty toasty when the sun is out. I was planning to move the seedlings out there, but I'm worried it still isn't warm enough, especially on days we don't have sun. I don't have a good way of keeping the new plants indoors as they grow because my cats will eat them. If we have cloudy to partly cloudy days with highs in upper 50s and lows in upper 30s/low 40s, is that too cold to have them in a cold frame? Are there ways I can insulate the cold frame to make it more hospitable? Other suggestions? Thanks!

Benton County Oregon

2 Responses

Thank you for your question. It is very difficult to start seeds for other than cold season plants outside until the weather gets much warmer. This article explains why the indoor method is critical, unless your greenhouse is adequately heated, lit and ventilated: https://extension.oregonstate.edu/news/save-money-starting-vegetable-seeds-home Plants planted (or transplanted) outside can easily develop root rot (a soil borne fungus) and you can lose them overnight unless the 60+ temperature is maintained 24/7. Here is another publication on vegetable gardening that may answer some other questions:
https://catalog.extension.oregonstate.edu/em9027

Good luck!

BTW, although it may wipe out your anticipated savings, you might want to consider purchasing a seedling heat mat. Just be sure, if you try it in your cold frame, that it can safely be operated outdoors. Even with the best of insulation, though, it will not keep the plants' above ground parts warm.