How long should I blanch vegetables?

Blanching is a brief plunge in boiling water (or steam) followed by an immediate ice bath. The technique softens vegetables slightly, brightens color, deactivates enzymes that cause spoilage, and partially cooks for further preparation or freezing.

Standard blanching times (in boiling salted water):

Leafy greens (30 sec–1 min): - Spinach: 30 sec (whole leaves) - Swiss chard, kale: 1–2 min - Collards (mature, tough): 3 min

Tender vegetables (2–3 min): - Green beans (haricots verts): 2 min - Snow peas: 1 min - Sugar snap peas: 1–2 min - Asparagus (thin): 1 min, (thick): 2 min - Broccoli florets: 3 min - Cauliflower florets: 3 min

Firmer vegetables (3–5 min): - Carrots (sliced 1/4"): 3 min - Carrots (whole): 5 min - Brussels sprouts (halved): 3 min - Brussels sprouts (whole): 4 min - Celery (chunks): 3 min - Bell peppers (strips): 3 min

Root vegetables (5+ min): - Beets (whole, small): 5–7 min - Turnips (cubed): 3–5 min - Parsnips (sliced): 4 min - Sweet potatoes (cubed): 5 min

Tomatoes (special case for peeling): - 30–60 seconds in boiling water until skin splits - Then immediately ice bath - Skin slips off cleanly

For freezer storage (blanching to deactivate enzymes): - Green beans for freezing: 3 min (extra-long, freezer prep) - Corn on cob: 7 min (longer for full enzyme deactivation) - Brussels sprouts for freezing: 4 min - Spinach for freezing: 2 min (longer than fresh-eating)

Why ice bath immediately: - Stops cooking instantly (residual heat would continue cooking) - Locks bright color (chlorophyll preservation) - Maintains crisp texture - 1 minute ice-bath = 30 sec less cook time

Method (standard): 1. Bring large pot of heavily salted water to rolling boil (1 tbsp salt per quart) 2. Prepare ice bath in separate bowl 3. Add vegetables in batches (don't crowd) 4. Time exactly per chart above 5. Use slotted spoon to transfer to ice bath 6. Let cool 1–2 min in ice bath 7. Drain + pat dry for storage/use

Steam-blanching alternative: - Less nutrient loss (no leaching into water) - Add 2 min to standard times (steam is gentler heat transfer) - Best for delicate vegetables (asparagus, broccoli)

Don't: - Crowd the pot (drops temp, uneven cook) - Skip the salt (drains nutrients, less flavor) - Skip ice bath (continued cooking + dull color) - Over-blanch (becomes soggy mush; aim for tender-crisp)

The "done" test: - Color: bright vibrant (chlorophyll preserved) - Texture: tender-crisp (gives slightly when bitten) - Smell: fresh, vegetal - Should NOT be: mushy, gray-green, soft throughout

Cross-reference: see /pages/how-long-does/dehydrating-fruit for related preservation method + /pages/how-long-does/sauerkraut-ferment for fermentation as an alternative preservation.

Most published references (Julia Child "Mastering the Art of French Cooking", James Beard "American Cookery", The Joy of Cooking, USDA Food Preservation Guides) converge on the timing ranges above as the home-cooking standard.