Potato: Root Vegetable
How to Plant
- Plant potatoes directly in the vegetable garden as soon as possible after you receive your mini-tubers. Potatoes are a cool season crop and mini-tubers should be planted prior to the last expected frost in spring if possible. Potatoes may also be grown as a fall crop in milder regions.
- Select a location in full sun with good rich moist organic soil. Make sure you did not grow tomatoes, peppers, eggplant or potatoes in the bed the previous year to avoid disease problems. Potatoes prefer a soil pH of 4.8 to 6.0. Avoid poorly drained soils. Do not plant potatoes in freshly turned grass sod to avoid wireworms.
- Prepare the bed by turning the soil under to a depth of 8 inches. Level with a rake to remove clumps of grass and stones.
- Plant the entire mini-tuber, do not cut it up into smaller pieces. Lay the mini-tuber in a trench 4-5 inches deep and 6-8 inches wide and apply a light fertilizer at the bottom of the trench. Space the potatoes 10 to 12 inches apart with eyes up and cover with 2 or 3 inches of soil in rows spaced 2 feet apart.
- If there is danger of frost cover the rows with newspaper until the shoots are 3-4 inches tall or the danger of frost is over. Plants emerge in 4-6 weeks.
- When plants are about 5 inches tall, hill up the soil from the sides of the trench around each plant almost covering the foliage, but allowing 2 inches of foliage to remain above the soil.
- Continue this hilling process as the plants grow, usually about every two weeks. The hills keep the plants cool and prevent the potatoes from forming near the surface where light will cause the tubers to turn green and become poisonous. Hilling suppresses weeds and keeps roots deep in the soil where more moisture is available.
How to Grow
- Keep weeds under control during the growing season. Weeds compete with plants for water, space and nutrients, so control them by either cultivating often or use a mulch to prevent their seeds from germinating. Cultivate carefully so as not to bruise or cut the young tubers forming just below the soil.
- It is important to keep plants well watered during the growing season to ensure enough water for potato development. They prefer 1-2 inches of water per week, more during hot, dry spells. Uneven growth caused by periods of drought when the tubers are forming (around flowering time) will decrease production and result in knobby, cracked or hollow tubers. Use a rain gauge to check to see if you need to add water. It’s best to water with a drip or trickle system that delivers water at low pressure at the soil level. If you water with overhead sprinklers, water early in the day so the foliage has time to dry off before evening, to minimize disease problems. Keep the soil moist but not saturated.
- In areas with sandy soil additional side dressings of fertilizer may be needed when the plants are about 12 inches tall and flowers first begin to appear.
- Monitor for pests and diseases. Check with your local Cooperative Extension Service for pest controls recommended for your area.
- Potato hills can be bordered with rows of other cool-season vegetables such as cabbage transplants, direct-Sown lettuce, celery, salad greens and root crops, onions, overwintered herbs, nasturtiums, and strawberry plants.
Harvesting and Preserving Tips
- Harvest “new potatoes” as soon as plants begin to flower, about 10 weeks after planting. Harvest mature potatoes about 15 weeks after planting.
- When harvesting new potatoes work carefully to disturb the plants as little as possible. With your hands and a trowel gently lift the top layer of soil or mulch around the plants and pick as many potatoes as needed, then replace and firm the soil or mulch. Take only a few of these immature potatoes from each plant. The remaining potatoes will continue to grow and provide your main crop. For best flavor and vitamin content, plan to use new potatoes immediately after digging.
- Dig mature potatoes for storing 2-3 weeks after the plants turn yellow and die back. Use a spading fork and work from the outside edge of each row, turning the soil over carefully so the potatoes are not damaged. Most of the crop will be in the top 6 inches of the soil. Harvest on a sunny day and leave them out to dry for an hour.
- After harvesting store them in a dark, dry place for a week at 65-70 degrees F. Then store them at 35-40 degrees F out of the light.
- Note: The leaves of potato plants are poisonous to humans and animals.
Common Disease Problems
Early Potato Blight: Infected leaves show dark brown, circular lesions with a concentric, bull’s eye pattern. Burpee Recommends: Foliar fungicides can reduce foliar symptoms, consult your Cooperative Extension Service for other recommendations. Reduce stress by watering and fertilizing regularly. Plant late varieties which are not as susceptible. Store tubers in a cool environment.
Gray Mold (Botrytis): The flowers may be covered with a fuzzy gray mold, wedge shaped tan lesions form on foliage, a slimy brown rot forms on the stems, tubers develop a wrinkly skin and the tissue underneath is soft and wet and develops a gray fuzzy growth. The disease is worse in high humidity, cool temperatures and shade. Burpee Recommends: Keep plants as healthy as possible by watering and fertilizing. Practice crop rotation. Consult your Cooperative Extension Service for other fungicide recommendations.
Potato Scab: This causes brown pustules or pits to develop on the tuber skin and extends into the tuber. It tends to be more of an issue during warm and dry conditions. Burpee Recommends: Only plant disease free tubers; rotate crops and do not plant in the same area for at least four years; plant resistant varieties and lower soil pH if it is above 6.0.
Root Knot Nematodes: Microscopic worm-like pests that cause swellings (galls) to form on roots. Plants may wilt or appear stunted. This is a serious problem in many Southern states. Burpee Recommends: Do not plant into infested soil. Grow resistant varieties. Try planting ‘Nema-Gone’ marigolds around your plants.
Verticillium Wilt: This soil borne fungus initially causes yellow v-shaped lesions on the lower leaves. Leaflets on one side of the branching stem die and if you cut the stem you can observe discolored tissue in the stem. Burpee Recommends: Practice crop rotation and plant resistant varieties.
Common Pest and Cultural Problems
Aphids: Greenish, red, black or peach colored sucking insects can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps which feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Colorado Potato Beetle: This insect is especially harmful at the larval stage. The larvae are plump, reddish orange soft bodied insects with dark heads and black markings. Adults are large beetles with yellow and black stripes. Burpee Recommends: Hand pick the larvae and destroy. Look for egg clusters on the undersides of the leaves and destroy. Check with your Cooperative Extension Service for pesticide recommendations.
Flea Beetles: These small hopping beetles feed on plant foliage and may spread diseases. Burpee Recommends: Rotate crops with plants in a different plant family. Use floating row covers to prevent damage to young foliage.
Leafhoppers: Leafhoppers cause injury to leaves and stunt growth. They also spread disease. Burpee Recommends: Remove plant debris. Use insecticidal soaps. Consult your Cooperative Extension Service for other insecticide recommendations.
Wireworms: These insects live in the soil and kill seedlings by girdling their stems at the soil line, bore into stems, roots and tubers. They may be found around the stems in the soil are and ¼ to ¾ inch long, thin, yellow brown worms with a shiny skin. The adults are called click beetles, and are about 1/3 inch long, reddish brown with a hard shell. Burpee Recommends: Rotate crops. Check with your Cooperative Extension Service for pesticide recommendations which must be applied prior to planting.
Do I need divide my mini-tubers into “eyes” before planting? No. Mini-tubers should be planted whole. Mini-tubers are “seed” potatoes and should not be divided or cut. Cut tubers are more likely to rot than uncut tubers.
Are your mini-tubers certified disease-free? Yes, our mini-tubers are certified disease-free from the Department of Agriculture of Washington State.
How many potatoes do I get from every mini-tuber? A mini-tuber can grow as many as 5-10 potatoes (1- 5 lbs.) depending on the length of the season and the vigor of the potato plant.
Do I need to cut off the flowers? Removing flowers and seeds conserves energy and makes a stronger plant and therefore more tubers. It is not necessary, however.
Can I grow potatoes from the supermarket? No. Most of these potatoes are treated with growth inhibitors.