Last Updated on October 9, 2026

How to Chit Potatoes Before Planting

Chit seed potatoes for 4 to 6 weeks before you plant them. Stand them rose end up (the end with the most eyes) in an egg carton or shallow tray in a bright spot out of direct sun, at about 70°F, until the sprouts are short, green and about half an inch to an inch long. Then cut any big ones into pieces with two sprouts each, let the cut faces callus for a couple of days, and plant 1 to 2 weeks before your last frost. Counted back from that planting window, you start chitting about 5 to 8 weeks before your last frost.

That is how I do it: I chit my seed potatoes four to six weeks ahead in a warm, bright spot until the sprouts are half an inch long, cut the big ones into pieces with two sprouts each, and let the cuts callus for two days (more in how many potatoes per square foot). Chitting is also called green sprouting or pre-sprouting. It just means waking the seed potato up indoors so it is already growing when it goes in the ground.

How to chit potatoes, step by step

1. Start with certified seed potatoes. University of Maine Cooperative Extension says not to use grocery store potatoes, because they are probably treated to not sprout.
2. Count back from your planting week. Plan My Garden plants potatoes 1 to 2 weeks before your last frost. Start chitting 4 to 6 weeks before that day. The timeline table below does the math.
3. Stand them in an egg carton, rose end up. Thrive, the UK gardening charity, puts one seed potato in each egg box compartment with the rose end up. That is the blunt end with the most eyes. The narrow heel end, where the potato was attached to the plant, goes down.
4. Give them warmth and bright shade. Utah State University’s commercial potato guide chits seed at about 70°F in medium light, bright shade and not direct sun. In its words, the warmth grows strong shoots and the bright light keeps the shoots short. Not every source agrees on temperature: Thrive, the UK gardening charity, chits at a cooler 45 to 54°F and warns that a heated room can shrivel the seed potatoes. The 70°F figure here follows the two U.S. extension guides, which assume an indoor spot that runs warmer than an unheated UK porch or greenhouse.
5. Check them every few days. You want short, stubby, green sprouts. If they start getting long, move the carton somewhere brighter. If they come up branched and hairy instead, that is old seed: the University of Maine’s seed handling bulletin, aimed at large-scale seed cutting (it gives seed-per-acre tables and talks about mechanical cutters), calls those sprouts weak and says they will not make a vigorous plant, so compost that piece instead of planting it.
6. Plant when the sprouts are half an inch to an inch long. Half an inch is my target. Utah State says about 1 inch at planting.
7. Cut big ones after chitting, not before. Utah State says cutting seed before green sprouting encourages it to dry out. Once the sprouts show, you can see where to cut so every piece gets two of them.
8. Let the cut pieces callus, then plant sprouts up. I give the cuts two days. Small whole seed potatoes need no cutting and go straight in.

Chitting timeline counted from your last frost

The planting window is the one the Plan My Garden planner uses for potatoes: direct sow 1 to 2 weeks before your average last spring frost. The chitting weeks are that window plus 4 to 6 weeks.

To turn those weeks into dates, look up your frost dates by zip code on Plan My Garden, or use my seed starting calendar. Do not plant earlier than the window just because the sprouts are ready. The foliage is frost-tender: if it gets nipped it recovers, but it costs the plant energy, as I wrote in how to grow potatoes in containers.

How to cut seed potatoes

Small seed potatoes go in whole. Bigger ones get cut into pieces about the size of an egg, and chitting makes this easier because you can see the sprouts. University of Alaska Fairbanks Cooperative Extension sizes it like this:

Only one eye is needed to grow. Alaska’s guide asks for two as a backup in case one gets damaged, and I cut for two sprouts per piece. A few more cutting rules:

• Make few, smooth cuts. The University of Maine says the fewer cut surfaces the better, so less of the potato’s energy goes into healing, and that jagged or torn cuts invite seed-piece rot. Make pieces blocky.
• Do not plant tiny seed. The University of Maine says not to use seed smaller than 1 inch across.
• Keep it clean. University of Minnesota Extension says to cut on a clean cutting board with a clean knife. Alaska’s guide washes the knife often, because a diseased potato can pass disease to the pieces cut after it. As a general rule, if you cut into one that looks rotten inside, throw it out and clean the knife before continuing.

For a rough count, University of Florida IFAS Extension says one pound of seed potatoes typically makes about six to eight egg-size pieces.

How to cure cut seed potatoes

Curing lets each cut face dry and form a tough skin before it goes into cool, damp soil. UF IFAS says you can plant pieces right after cutting, but doing so raises the risk that they rot before they sprout.

The sources land close together: about 60 to 70°F for one to a few days, then plant. If you cut well ahead of planting, the University of Maine says to store the pieces at 50 to 55°F and over 90 percent humidity so the cuts heal.

Planting chitted potatoes

Handle them gently. University of Minnesota Extension says to plant cut side down and be careful not to rub off the sprouts. I plant mine 4 inches deep, one or two to a square foot, sprouts up; the spacing is in how many potatoes per square foot. Hilling and the rest of the season are in planting and growing potatoes, and the fabric-pot version, which is how I grow most of mine now, is in how to grow potatoes in containers.

Is chitting potatoes worth it?

For early potatoes, yes. For a late, main-crop potato, it matters less.

• Faster start. Utah State’s commercial guide says green sprouting speeds emergence and tuber development, and that combined with close spacing (about 6 inches) it can bring harvest 7 to 14 days earlier. That guide is written for commercial growers, and the 7 to 14 days goes with close spacing for small new potatoes, so treat it as a rough guide for a backyard bed.
• Best for early varieties. The Royal Horticultural Society calls chitting worthwhile for early varieties and sees no real advantage for main-crop varieties, which grow over a much longer season. It also says unchitted early potatoes still grow well and just take a few weeks longer to crop.
• Not required. If you run out of time, plant them unchitted inside the same 1 to 2 week window.

One safety point: chitted seed potatoes are for planting, not eating. UF IFAS says solanine is concentrated in green tubers and in new sprouts, and that it is toxic at very low levels. Chitted seed potatoes always have the new sprouts, and often some green from weeks in a bright spot.

Where I get seed potatoes

I buy certified organic seed potatoes from Wood Prairie Family Farm in Maine. Their seed potato list includes Yukon Gold, Dark Red Norland and Adirondack Blue. Code PMG5 takes 5 percent off.

Quick questions

How long does it take to chit potatoes?

About 4 to 6 weeks. I chit mine four to six weeks ahead until the sprouts are half an inch long, and the Royal Horticultural Society also says the process takes four to six weeks. Utah State’s potato guide plants when the sprouts are about 1 inch long.

When should I start chitting potatoes?

Count back 4 to 6 weeks from your planting day. The Plan My Garden planner plants potatoes 1 to 2 weeks before your last frost, so start chitting about 5 to 8 weeks before your last frost.

Do you have to chit potatoes before planting?

No. The Royal Horticultural Society says unchitted early potatoes still grow perfectly well and just take a few weeks longer to crop, and it sees no real advantage to chitting main-crop varieties.

Should I cut seed potatoes before or after chitting?

After. Utah State’s potato guide says cutting seed before green sprouting encourages it to dry out. Once the sprouts show, cut big potatoes into pieces with two sprouts each and let the cuts callus for a couple of days before planting.

Can you eat chitted potatoes?

No, keep them for planting. University of Florida IFAS Extension says solanine is concentrated in green tubers and new sprouts and is toxic at very low levels.

Know your planting week

Chitting only works if you count back from the right day, and that day comes from your last frost. Enter your zip code on Plan My Garden and it finds your frost dates. Plan My Garden is free to start: enter your zip code, draw your beds, pick potatoes and everything else you want to grow, and it places each plant at square-foot spacing and builds a planting schedule (start indoors, transplant and direct sow dates) from your frost dates.

Related: Planting and Growing Potatoes · How Many Potatoes per Square Foot? · How to Grow Potatoes in Containers · Seed Starting Calendar