The following article appears on the Eagle Creek Seed Potatoes website and is reused with permission from the author, John Mills.
Often you will purchase your seed potatoes long before your garden is ready or the soil is warm enough to plant.
We recommend waiting until the soil reaches 10 °C (50 °F). If it’s any colder, the potatoes will sit in the ground until the ground warms.
Step #1 Open the Bag
Remove your potatoes from the bag they were shipped in. If you leave them in the bag, they may produce long white fragile sprouts.
Step #2 Green Sprouting
Skip this step if your garden is ready for planting.
Place your potatoes in a well-lit area, but not full sun. Instead of growing long white sprouts (as often happens in your pantry), the potatoes will grow a small rosette of leaves not much bigger than a quarter. When your soil warms up, plant the potatoes as you normally would.
Green-sprouted potatoes can sometimes be ready for harvest up to 10 days earlier than non-sprouted potatoes.
Twenty-one days of green sprouting is the recommended time. We have, however, sprouted potatoes nearly 6 weeks before planting with no negative effects on the tubers.
Step #3 Fertilize
Nutrition is key to a healthy potato plant and a fantastic harvest of potatoes.
Nutrition can be applied in spring, fall & through the growing season and can come from incorporating a cover crop grown the previous year, adding compost or through organic or non-organic fertilizers.
Adding too much compost can cause your potatoes to become scabby and too much readily available nitrogen can result in potato plants that are all leaves and no potatoes.
We have had great success with incorporating cover crops combined with organic fertilizers that are applied at the time of planting.
Step #4 Planting
When growing in a garden, we recommend allowing for 2–3 square feet (0.2-0.3 m2) per plant.
Dig a hole only 3 inches (7.5 cm) deep, place the potato in the hole and cover with only 1 inch (2.5 cm) of soil. You want the potatoes leaves to reach the surface as soon as possible.
Once the leaves are 3–5 inches (7.5 to 12 cm) above the ground, you can start to hill up dirt around the stem. It’s OK to cover the leaves in dirt; they will push through the soil again. Continue to mound the dirt up as the potatoes grow until your mound is 6–10 inches (15–25 cm) tall and 12–18 inches (30–45 cm) wide.
This mound of dirt will be where your potatoes will form.
Step #5 Water and Monitor
Potatoes produce many leaves and require lots of water. You don’t want soggy wet soil, however, yet if you let the ground dry out completely, your harvest may be less than expected. Dry soil may also stress your potato plants, causing their natural defenses to weaken, allowing bacteria such as scab or rhizoctonia to latch onto the skin. A healthy potato plant can fight off most insects and diseases that can cause harm to your crop.
Step #6 Harvest
There are many rules of thumb which may or may not work, such as “wait until the potato has flowered before harvesting.” Unfortunately, not all potato varieties will flower. We recommend digging in the side of your potato hill with your hand periodically to see how large the potatoes are getting. If you like big potatoes, leave them until the first frost. If you like small potatoes, keep a close eye on them, as potatoes can double in size each week.
There you go! Advice from an expert on how to grow the best potatoes possible!