Planting and Caring Potatoes in a Growing Bag

IF YOU MUST DELAY PLANTING: If you need to store your potato minitubers before planting them, keep the bag in a cool (40-50°F), well-lit place. The eyes may begin to form chubby little sprouts, but this just indicates that they are ready to grow. Do not remove these sprouts. If the potatoes are stored in a warm, dark place, however, they will make long pale shoots, which will weaken the plants.

PLANTING AND CARING FOR POTATOES IN A FABRIC GROWING BAG:

1. About 2-3 weeks before the local frost-free date, set up your porous-fabric growing bag in a sunny spot where it can remain all season and can drain freely when watered. Place about 6in of good quality potting soil in the bottom of the bag. You can mix in 3-4 quarts of compost or aged manure ahead of planting, or top dress afterwards. Too much nitrogen will cause lush top growth at the expense of tubers. Do not use fresh manure as it can cause potato scab.

2. For each tuber, make a hole about 2-3in deep, insert the tuber, and cover with potting mix. We suggest planting 3 tubers per growing bag (too many plants in one bag will compete with each other and decrease yields). Once all the tubers are planted, water the potting mix.

3. It will take a few days before your tubers start growing and poke leafy stems through the potting mix. During this time, feel the top 1in of potting mix with your finger and water the mix if it is dry. Please note: The tubers can rot if they are kept too wet.

4. When plants are 6-8in tall, gently add more potting soil in the growing bag around each young potato plant, leaving about 4in of the leafy plant exposed (this is called hilling up). Be careful not to damage the roots.

5. Continue to hill up soil or mulch heavily as your plants grow. This increases yields by providing more room beneath the soil surface for potatoes to form.

6. Watch for insects, and use appropriate controls if they become a problem. Bt (Bacillus thuringiensis) can be helpful in dealing with potato beetle larvae. Pyola® Insect Spray or Neem products are effective in controlling adult potato beetles.

7. Potatoes require at least 1in of rainfall per week while actively growing. Water your plants thoroughly if there is no rainfall. To determine whether they need water, check the plants in the morning when it is still cool. If the growing tips are wilting, water deeply.

HARVESTING NEW POTATOES: After 60 days or so, plants will flower and little tubers will begin to form on underground stems called stolons. Some varieties either bloom very late or not at all, so check for new potatoes after 65-75 days on plants that don't bloom. Gently probe around the base of the plant for developing tubers on the ends of stolons (some stolons are as long as 18in). Dig up only enough baby-sized potatoes for one or two days' use, as they are perishable. While it's a treat to harvest some of your crop as new potatoes, leave most of the crop to mature for later harvest and storage.

HARVESTING YOUR MAIN CROP: For your main potato crop, allow growth until vines naturally wither or until tubers have reached the desired size. Frost will encourage maturing. If tubers are fully formed and continue to produce vigorous top growth, break the tops off at ground level to stop growth. Allow the tubers to remain in the soil at least two weeks after tops have died back or have been broken off. Don't water plants during this period. This provides time for skins to "set," which increases storage life. Dig potatoes carefully so as not to bruise or damage skins. Dig deeply or remove the potting mix from the growing bag to locate all tubers. Injured tubers should be cooked and enjoyed right away. Potatoes will turn green and taste bitter if stored in the presence of light. For this reason, we recommend storing them in brown paper bags at low temperatures; 35-40°F is optimal. Cool temperatures retard sprout development and increase storage life. Do not store potatoes in the refrigerator; the atmosphere is too dry for them to keep well.

NEXT YEAR'S CROP: Scab is a common disease in potatoes. It makes them unattractive and reduces storage life. Planting clean seed, such as ours, in loose, well-drained potting mix reduces the risk of scab. Moist soil is required during the development of tubers, but the soil should not be soggy. Growing potatoes in potting mix with a pH above 6.5 can increase scab problems. Take care to harvest your entire potato crop; don't leave any tubers in the growing bag. Also, replace the potting mix in your growing bag each year.

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