How to Grow Sprouts in a Jar

By the Countertop Harvest team · Last updated October 20, 2026 · How we choose products

Sprouts are the fastest crop we grow. The University of Vermont says you can grow them at home in a few days with very little equipment (UVM Extension), and a jar on the counter is all most of us need. They also carry a food safety risk that other kitchen crops don't, so we put that section first. Please read it before your first batch. After that, we cover seeds, the jar method step by step, harvesting and storage.

Food safety first

The University of California's guide to home sprouting gives the background. Since 1995, raw sprouts have been a significant source of foodborne illness in the United States, and while alfalfa, clover and mung bean sprouts have been involved most often, all raw sprouts may pose a risk (UC ANR). In most outbreaks the seed was the source of contamination, and even lightly contaminated seed can reach millions of bacteria per serving during sprouting (UC ANR). UC adds that cooked sprouts can be eaten if heated until steaming hot or above 165°F (UC ANR).

Here is what we do in our kitchen, based on those sources:

• Cook sprouts for anyone at higher risk. We stir-fry or add them to soup for kids, older relatives and anyone pregnant or with a weakened immune system (FDA; UC ANR).
• Buy seed sold for sprouting. UC suggests buying certified pathogen-free seed and asking for that certification specifically, noting that "organic" doesn't mean the seed has been tested for pathogens (UC ANR). NC State warns never to use seed treated with fungicide, which often shows a pink or green dust on the seed coat (NC State Extension).
• Keep everything clean. UC sprouts seed in clean, sanitized containers away from food preparation areas, pets and busy parts of the house (UC ANR). It sanitizes containers by soaking them for at least 5 minutes in a solution of ¾ cup of bleach per gallon of water (3 tablespoons per quart), then rinsing with clean water (UC ANR). Vermont washes sprouting containers in hot, soapy water (UVM Extension).
• Throw out anything that looks off. Vermont discards sprouts with black spots, brown discoloration, sliminess or anything else that seems wrong (UVM Extension).

What about treating the seed?

UC's home guide describes heating seed for five minutes in 3% hydrogen peroxide held at 140°F, then rinsing (UC ANR). A 2023 laboratory study from UC Santa Cruz later found that 3% hydrogen peroxide was not consistently effective at reducing microbes on sprouting seed, and that heat strong enough to cut microbes meaningfully also hurt germination (UC Santa Cruz study). In that study, dilute household bleach and freshly made hypochlorous acid worked best on the seeds tested (UC Santa Cruz study), while UC's home guide says chlorine at the levels the sprout industry uses is not recommended for treating seed at home (UC ANR). Our takeaway is that no home seed treatment we know of makes raw sprouts safe for people at higher risk, which is why we cook theirs.

Which seeds to sprout

Vermont lists mung beans, alfalfa, broccoli, radish, peas, mustard and sunflower as popular sprouting seeds, with lentils, wheat, rye and buckwheat gaining ground (UVM Extension). Vermont also notes that seed sold specifically for sprouting usually comes in larger quantities with instructions (UVM Extension). If you'd like to compare, here are the SeedsNow sprout seed variety pack, Botanical Interests salad mix sprouting seeds and a SeedsNow sprout kit. Whatever you buy, ask the seller about pathogen testing, as UC suggests (UC ANR).

The jar method, step by step

Vermont uses a wide-mouth mason jar with a sprouting lid, which lets water drain between rinses; cheesecloth held on securely, or a colander over a bowl, works too (UVM Extension). If you'd like a mesh lid, here are wide-mouth sprouting lids on Amazon.

1. Measure and rinse. Vermont starts with 1 tablespoon of seed (UVM Extension). NC State washes the seed before soaking (NC State Extension).
2. Soak. Follow the packet. Without directions, Vermont soaks small seeds like alfalfa and broccoli for 6 to 8 hours and large seeds like mung beans and peas overnight (UVM Extension). NC State uses lukewarm water for 6 to 8 hours or overnight (NC State Extension).
3. Drain well. Pour off the water and stand the jar upside down in a bowl at an angle so it keeps draining. Vermont's goal is seeds that are damp but never sitting in water (UVM Extension).
4. Keep it dark. Vermont keeps sprouts in a cabinet or under a towel (UVM Extension). NC State says sprouting works best at 70 to 80°F in a dark place (NC State Extension).
5. Rinse and drain twice a day. Vermont repeats this for three to six days (UVM Extension), and NC State waters 2 to 3 times a day (NC State Extension). NC State prefers non-chlorinated water, because it says chlorine in city water can cause poor sprouting (NC State Extension).

When they're ready

Vermont says sprouts are ready when they have leaves and the seed hulls start to fall off (UVM Extension). NC State's timing is 3 to 7 days depending on temperature, and for mung beans it grows sprouts to 2½ to 4 inches, warning that sprouts over 4 inches may turn bitter (NC State Extension). To clean them, NC State puts the sprouts in a bowl of water; the sprouts sink and the hulls float, so the hulls can be skimmed off (NC State Extension).

Storing sprouts

Vermont gives sprouts a final rinse, pats them as dry as possible and refrigerates them, and says most varieties last about five days (UVM Extension). NC State stores them at 38 to 50°F in closed containers (NC State Extension). For a steady supply, NC State starts a new batch every three days (NC State Extension).

Common problems

Musty smell or slimy sprouts

Throw them out (UVM Extension). Vermont says poor airflow and poor drainage are the most common causes, so drain more thoroughly and keep the jar tilted.

Seeds that won't sprout

Check the water and temperature. NC State says chlorinated tap water can cause poor sprouting, and that 70 to 80°F works best (NC State Extension).

Bitter sprouts

They may have grown too long. NC State notes sprouts over 4 inches can turn bitter (NC State Extension).

Sprouts vs. microgreens

Sprouts grow in water in a jar and we eat the whole seedling, seed and root included. Microgreens grow in a tray of mix in the light and are cut above the soil. See microgreens on your counter for that method, or lettuce and salad greens indoors. You can also find a guide by plant.

Sources

• U.S. Food and Drug Administration: Selecting and serving produce safely
• University of California Agriculture and Natural Resources, Publication 8151: Growing seed sprouts at home (PDF)
• Gilbert, Diaz and Bregoff (UC Santa Cruz), Foods 12(4):747, 2023: Seed disinfestation practices to control seed-borne fungi and bacteria in home production of sprouts
• University of Vermont Extension: Sprouts, the superfood to grow at home (2025)
• NC State Extension, Horticulture Information Leaflet: Bean sprouts and other vegetable seed sprouts

All sources accessed October 20, 2026. This guide is general information about home sprouting and is not medical or food safety advice for your situation. If you are in a higher-risk group, follow the FDA advice above.

Frequently asked questions

Are homegrown sprouts safe to eat raw?

They carry a risk. The FDA says bacteria on seeds can grow to high levels during sprouting even under sanitary home conditions, and advises children, older adults, pregnant women and people with weakened immune systems to avoid raw or lightly cooked sprouts. UC ANR says cooked sprouts are fine when heated until steaming hot or above 165°F.

How long do sprouts take to grow in a jar?

University of Vermont Extension rinses and drains twice a day for three to six days, and NC State Extension gives 3 to 7 days depending on temperature.

How long should I soak sprouting seeds?

Follow the packet. Without directions, Vermont Extension soaks small seeds such as alfalfa and broccoli for 6 to 8 hours and large seeds such as mung beans overnight.

Do sprouts need light?

No. Vermont Extension keeps sprouts in a dark cabinet or under a towel, and NC State says sprouting works best at 70 to 80°F in the dark.

How long do sprouts last in the fridge?

Vermont Extension says most sprouts last about five days refrigerated after a final rinse and drying. Throw out any that turn slimy, brown or smell off.