How to grow Organic Potatoes
Potatoes always do best in full sun. They are aggressively rooting plants and will produce the best crop when planted in a light, loose, well-drained soil. Fortunately, potatoes are very adaptable and will almost always produce a respectable crop, even when the soil conditions and growing seasons are less than perfect. Always keep your potato patch weed-free for best results. Potatoes should be rotated in the garden, never being grown in the same spot until there has been a 3-4-year absence of potatoes. This will help you avoid diseases.
Potatoes may be planted as soon as the ground can be worked in the early spring as soon as the soil temperature has reached 45 degrees F. We ALWAYS use a soil thermometer (sold at Natureworks) to check the soil temperature before planting. The soil should be moist, but not water-logged. Potatoes can tolerate a light frost, but you should provide some frost protection for the plants if you know that a hard freeze is coming.
Always test your soil before growing vegetables for the first time. Potatoes grow best in a pH of 4.8-6.5. An acidic soil is preferred to inhibit the growth of scab, a disease of potatoes. Your soil should be well drained and amended with Coast of Maine lobster compost. A well-balanced organic fertilizer blend such as North Country Organics Pro Gro should be worked into the soil along with the compost before planting. If your soil tends to be on the heavy side, work in coir (coconut fiber, sold at Natureworks) to lighten it. Coir is an excellent, sustainable alternative to peat moss.
The most common way to grow potatoes is to use what are called “seed potatoes”, specially grown small potatoes that are certified disease free. At Natureworks, we sell only organic certified disease-free potatoes. The best part of growing your own potatoes is that you can try lots of different varieties. Potatoes are classified as early, mid, and late season. Some are labeled as “good keepers” meaning they store well over the winter. Try fingerlings as well as gold, pink, red, and blue potatoes. The other benefit of growing your own potatoes is that NOTHING beats the taste of a freshly dug potato!
A new development in growing potatoes is the availability of potato seed. Yes, potatoes CAN be grown from seed. The process takes longer but it is a very affordable way to grow potatoes. Natureworks started carrying potato seed in 2021.
A day or two before planting, use a sharp, clean knife to slice the larger seed potatoes into smaller pieces. Each piece should be approximately 2 inches square and must contain at least 1 or 2 eyes or buds. Smaller potatoes may be planted whole. A good rule of thumb is to plant them whole if they are smaller in size than a golf ball. Lay out the cut seed potatoes in the sun, or in a dry, sheltered spot for 1-2 days. As soon as you see the cut areas form a thick callous, you are ready to plant.
Prior to planting, always make sure to cultivate the soil. If you are planting in raised beds or established garden beds that have been covered with mulch, pull aside the mulch and loosen the soil with a digging fork and rake it smooth. If you are breaking new ground, turn over the soil at least one shovel depth, loosen with a digging fork and rake smooth. Remove any weeds and rocks.
To begin with, dig a trench that is 6-8 inches deep. Plant each piece of potato (cut side down, with the eyes pointing up) every 12-15 inches, with the rows spaced 3 feet apart. If your space is limited or if you would like to grow only baby potatoes, you can decrease the spacing between plants. To begin with only fill the trench in with 4 inches of soil. Let the plants start to grow. As soon as shoots and leaves reach about 6-8” tall, add more soil to the trench and carefully mound the soil around the plants. Do this as your potato plants continue to grow until the trench is filled. Mulch your potato plants with a thick layer of Mainly Mulch shredded straw. The better you are at mounding up and thickly mulching your potatoes, the more tubers will grow underground. Potato tubers must not be exposed to light or they will turn green. Green potatoes cannot be eaten.
You don’t have to plant your potatoes in the ground or in raised beds. Potatoes are a great crop to grow in Smart Pot grow bags. The ratio of seed potatoes to gallons is; 1 seed potato per 3 gallons of container space. At Natureworks, we grow our potatoes in 20-gallon Smart Pots using 7-8 seed potatoes per bag.
• Add 12” of Castine Blend Raised Bed Soil or Organic Mechanics Potting Soil mixed 3 to 1 with Coast of Maine Lobster compost to the bottom of your 20-gallon Smart Pot. Place the seed potatoes cut part down, eyes up. Cover with 4” more of your chosen planting mix. Roll down the sides of the Smart Pot to the top of the soil. As the sprouts and leaves grow, continue to add soil and roll up the sides until the Smart Pot is full. Mulch the top with Mainly Mulch shredded straw.
• Smart Pots allow air to flow freely through the root system. They will need to be watered regularly as they will dry out more quickly than potatoes planted in the ground
Keep your potato vines well watered throughout the summer, especially during the period when the plants are flowering and immediately following the flowering stage. During this flowering period the plants are creating their tubers and a steady water supply is crucial to good crop outcome. Potatoes do well with 1-2 inches of water or rain per week. Deep soaking is critical. We feed our potatoes with Neptune’s Harvest Fish Emulsion and Liquid Seaweed every two weeks during the growing season, stopping when the flowers fade. You can also sidedress your potatoes with a blended organic fertilizer such as Pro Start in mid-summer. This encourages strong root growth and abundant flowering. When the foliage turns yellow and begins to die back, discontinue watering. This will help start curing the potatoes for harvest time.
Baby potatoes typically can be harvested 2-3 weeks after the plants have finished flowering. Gently dig around the plants to remove potatoes for fresh eating, being careful not to be too intrusive. Try to remove the biggest new potatoes and leave the smaller ones in place so they can continue to grow. Only take what you need for immediate eating. Homegrown new potatoes are a luxury and should be used the same day that they are dug. Potatoes that are going to be kept for storage should not be dug until 2-3 weeks after the foliage dies back. Carefully dig potatoes with a sturdy fork and if the weather is dry, allow the potatoes to lay unwashed for a few days to dry in a covered, dry place like a shed or back garage. This curing step allows the skins to mature and is essential for good storage. Avoid harvesting after a period of heavy rain. Let the soil dry out before harvesting potatoes that you plan on storing.
In an effort to provide horticultural information, these educational documents are written by Nancy DuBrule-Clemente and are the property of Natureworks Horticultural Services, LLC. You are granted permission to print/photocopy this educational information free of charge as long as you clearly show that these are Natureworks documents.