Cold Tolerance for Onion & Cabbage Seedlings: Expert Q&A
📌 Quick Summary: Managing Cold & Stalling Growth
- 🧅 Onion Seedlings in the Cold: Older onion seedlings thrive in cool weather. Keeping them at 55°F (13°C) on an unheated balcony during the day is perfectly fine, but bring them indoors if the nights get freezing.
- ✂️ Root Pruning Cabbage: When transplanting cabbage seedlings, pinching off the tip of the taproot is highly beneficial. It forces the plant to immediately grow lateral roots, which absorb the bulk of the nutrients.
- 🥦 Stalling Brassicas in Bad Weather: Cabbage and broccoli sprout fast and get leggy instantly indoors. If your spring weather is delayed, sprouting them in paper towel rolls (instead of dirt cups) allows you to “hold them back” for a couple of weeks without them stretching.
What is the Ideal Temperature for Onion Seedlings?
Lyuda, is that too cold for onions?
Cabbage Seedlings: Pruning Roots & Holding Them Back
I want to clarify one more thing about starting brassicas. If you sow cabbage directly into dirt pots indoors right now, it will sprout and instantly become leggy and weak from the indoor heat. That kind of cabbage seedling is useless.
The only way to succeed indoors is to sprout them in the light and keep them cool. If the spring weather outside is terrible and the ground is frozen, sprouting them in paper towel rolls allows us to “hold them back” in this state for a couple of weeks. Plus, they take up virtually zero space like that!
Same goes for radishes. One year I started radishes in paper rolls, moved them to the greenhouse, and everything was great. But when I tried transplanting them directly into the outdoor garden beds, they died. I transplanted them when they were too small—I probably should have potted them up into plug cells until they grew true leaves first. Honestly, it’s too much of a hassle; it’s much easier to just direct-sow radishes into the dirt!
