How-to Guide
Freezing Garden Vegetables: The Blanching Step and Per-Crop Times
The short answer
Blanching is a short scald in boiling water or steam that stops enzyme action, and NCHFP explains it "slows or stops the action of enzymes which cause loss of flavor, color and texture," while it also cleans the surface, brightens color, and helps retard vitamin loss. Those enzymes keep working slowly even in a home freezer, so an unblanched bean or pea will turn tough and off-flavored over a few months.
The times are crop-specific and short: snap beans 3 minutes, green peas 1.5 minutes, broccoli flowerets 3 minutes in water, medium corn-on-the-cob 9 minutes. Use the NCHFP chart for the exact time and do not eyeball it, because underblanching stimulates enzymes and is worse than no blanching at all. The moment the time is up, plunge the vegetable into ice water for as long as you blanched it, then drain thoroughly.
A few vegetables (beets, pumpkin, winter squash, sweet potatoes) are cooked fully rather than blanched. Pack cooled, drained vegetables into freezer bags or rigid containers, remove as much air as you can, label with the date, and freeze quickly.
Why blanching is not optional
Fresh vegetables are full of active enzymes. Freezing slows those enzymes down but does not switch them off, so an unblanched vegetable keeps degrading in the freezer and comes out tough, faded, and stale-tasting. The blanch is a heat shock that deactivates the enzymes so the vegetable holds its quality for months. NCHFP notes it also cleanses the surface of dirt and organisms, brightens the color, and helps retard loss of vitamins.
There is one counterintuitive rule that matters: too little heat is worse than none. Underblanching stimulates enzyme activity rather than stopping it, so a rushed or too-short blanch actively speeds up the loss of quality. That is exactly why you use a timer and the published time for each crop instead of guessing.
How to blanch, step by step
- 1Boil a big pot of water — Use about a gallon of water per pound of prepared vegetables so the water returns to a boil quickly after you add them. Have a large bowl of ice water ready alongside.
- 2Time from when water returns to a boil — Lower the vegetables in, cover, and start timing as soon as the water is boiling again. Use the exact NCHFP time for that crop and size.
- 3Cool in ice water for the same time — As soon as the time is up, transfer immediately to ice water. Cool for at least as long as you blanched, so the vegetable stops cooking; incomplete cooling leaves it soft.
- 4Drain, pack, and freeze — Drain thoroughly, pack into freezer bags or rigid containers leaving little air, press out excess air, label with the date, and freeze.
⚠ Underblanching stimulates the enzymes you are trying to stop and is worse than not blanching at all. Always use a timer and the exact NCHFP time for each vegetable; do not eyeball it.
Water-blanching times, straight from NCHFP
These are water-blanching minutes unless noted as steamed, taken verbatim from the NCHFP chart. Asparagus: small stalk 2, medium 3, large 4. Snap, green, or wax beans: 3. Lima/butter beans: small 2, medium 3, large 4. Broccoli flowerets (about 1.5 inches across): 3 in water, or 5 steamed. Brussels sprouts: small heads 3, medium 4, large 5. Shredded cabbage or Chinese cabbage: 1.5. Carrots: small whole 5; diced, sliced, or strips 2. Cauliflower flowerets (about 1 inch): 3. Celery: 3. Corn-on-the-cob: small ears 7, medium 9, large 11. Whole-kernel or cream-style corn: 4. Eggplant: 4.
Continuing verbatim from the chart: collard greens 3, all other greens 2. Kohlrabi: whole 3, cubes 1. Mushrooms (all steamed): whole 5, buttons or quarters 3.5, slices 3. Okra: small pods 3, large 4. Peas: edible pod 1.5 to 3, field/blackeye 2, green 1.5. Sweet peppers: halves 3, strips or rings 2. New Irish potatoes: 3 to 5. Rutabagas: 3. Green soybeans: 5. Summer squash: 3. Turnip or parsnip cubes: 2. Note that beets, pumpkin, winter squash, and sweet potatoes are cooked through rather than blanched. For anything not listed here, or full step-by-step directions, use the NCHFP freezing pages linked below.
Sources
Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.
- NCHFP - Blanching (Freezing) — Water-blanching times (minutes) verbatim: asparagus small 2 / medium 3 / large 4; snap, green or wax beans 3; lima beans small 2 / medium 3 / large 4; broccoli flowerets ~1.5 in 3 (water) or 5 (steamed); Brussels sprouts small 3 / medium 4 / large 5; shredded cabbage 1.5; carrots small 5, diced/sliced/strips 2; cauliflower flowerets ~1 in 3; celery 3; corn-on-the-cob small 7 / medium 9 / large 11; whole-kernel/cream corn 4; eggplant 4; collard greens 3, all other greens 2; kohlrabi whole 3 / cubes 1; mushrooms steamed whole 5 / buttons-quarters 3.5 / slices 3; okra small 3 / large 4; peas edible-pod 1.5 to 3, field 2, green 1.5; sweet peppers halves 3 / strips-rings 2; new potatoes 3 to 5; rutabagas 3; green soybeans 5; summer squash 3; turnip/parsnip cubes 2; beets, pumpkin, winter squash, and sweet potatoes are cooked (not blanched).
- NCHFP - Drying Fruits and Vegetables (blanching purpose) — Blanching "slows or stops the action of enzymes which cause loss of flavor, color and texture," cleanses the surface of dirt and organisms, brightens the color, and helps retard the loss of vitamins.