How to Blanch Vegetables
Updated August 15, 2026
Blanching is a short dip in heavily salted boiling water — 30 seconds to 4 minutes depending on the vegetable — followed immediately by an ice-water plunge to stop the cooking. It locks in bright color, tames raw crunch, and is mandatory prep before freezing vegetables.
| Vegetable | Time in boiling water |
|---|---|
| Spinach / leafy greens | 15–30 seconds |
| Snap peas / snow peas | 60–90 seconds |
| Green beans | 2–3 minutes |
| Broccoli / cauliflower florets | 2–3 minutes |
| Asparagus | 2–3 minutes by thickness |
| Carrots (sliced) | 2–3 minutes |
| Corn on the cob | 4 minutes |
| Tomatoes / peaches (to peel) | 30–60 seconds, until skins split |
Why bother
Heat deactivates the enzymes that dull color and degrade texture — a blanched green bean is greener than a raw one ever looked, and it stays that way. For freezing, blanching isn't optional: those same enzymes keep working at freezer temperatures, and unblanched frozen vegetables go drab and off-flavored within weeks. It's also the peeling trick for tomatoes and stone fruit — a 30-second dip and the skins slide off.
The two-bath rhythm
Big pot of aggressively salted boiling water, big bowl of ice water beside it. Work in batches small enough that the water barely stops boiling, fish the vegetables out at the time above, and plunge them until fully cool — the ice bath is half the technique, because carryover heat will finish the job into mush without it. Drain well and dry before freezing or sautéing; wet vegetables steam. Restaurants prep almost every green vegetable this way, then finish in a hot pan to order.
Quick answers
- Do I have to blanch vegetables before freezing?
- Yes for quality — enzymes keep degrading color and flavor in the freezer. The exceptions are peppers and onions, which freeze acceptably raw.
- Why salt the blanching water?
- Like pasta water, it's the only moment seasoning reaches the inside — and it helps preserve color. Salt it generously; almost none is retained.
- Can I reuse the blanching water?
- Yes, batch after batch in one session — and blanch light vegetables before strong ones (greens before broccoli).