If you’re planning your garden in Maine, knowing when to plant potatoes is the first step to a successful harvest. Getting the timing right is crucial in our unique climate, where a late frost can surprise you in spring and fall comes early.
This guide will walk you through the best planting dates, how to prepare, and how to care for your crop all season. You’ll learn how to work with Maine’s weather to grow a bounty of spuds.
When to Plant Potatoes in Maine
The classic rule for planting potatoes in Maine is to get them in the ground around the time of the last spring frost. For most of the state, this target window is from late April through mid-May.
Here’s a more detailed breakdown by region:
- Southern & Coastal Maine (Zones 5b-6a): You can often start planting in the last week of April. The moderating influence of the ocean gives you a slight head start.
- Central & Mid-Coast Maine (Zone 5a): Aim for the first two weeks of May. This is the standard timing for much of the state.
- Northern & Western Maine (Zones 3b-4b): Wait until mid-to-late May. It’s essential to let the soil warm up sufficiently in these cooler areas.
A great natural sign to watch for is when dandelions start to bloom. This is a good indicator that soil temperatures are approaching the ideal 45-50°F needed for potato seed pieces to grow well.
Why Timing is Everything
Planting too early in cold, wet soil can cause your seed potatoes to rot before they sprout. It also makes them vulnerable to a hard frost that can damage new growth.
Planting too late, however, shortens your growing season. Potatoes need time to develop fully before the first fall frost, which can arrive as early as September in parts of Maine. Missing the spring window risks your crop being caught by cold weather in autumn.
Choosing the Right Potato Varieties for Maine
Selecting varieties suited to a shorter growing season improves your chances for success. Look for early and mid-season types.
- Early Season (65-80 days to harvest): These are excellent for getting a quick crop. Try ‘Caribe’ (purple skin), ‘Dark Red Norland’, or ‘Yukon Gold’.
- Mid-Season (80-90 days): These offer great storage potential. ‘Kennebec’ is a Maine favorite for its reliability and disease resistance. ‘Red Pontiac’ and ‘Superior’ are also fantastic choices.
Always buy certified disease-free seed potatoes from a reputable source. Don’t use potatoes from the grocery store, as they may carry disease or be treated to prevent sprouting.
Preparing Your Seed Potatoes
About 2-3 weeks before your planned planting date, you need to “chit” or green-sprout your seed potatoes. This gives them a strong start.
- Place your seed potatoes in a single layer in a cool, bright spot (like a windowsill).
- Eye-side up is best, so the sprouts grow from the correct end.
- You’ll soon see short, sturdy green sprouts forming. This process is called chitting.
On the day before planting, you can cut larger seed potatoes into pieces. Each piece should be about the size of a golf ball and must have at least 2-3 strong sprouts. Let the cut pieces air-dry for a day to form a callus over the cut surface, which helps prevent rot.
Soil and Site Preparation
Potatoes thrive in loose, well-drained soil with a slightly acidic pH (5.8 to 6.5). They love full sun—at least 6-8 hours per day.
- Choose a spot that hasn’t grown potatoes, tomatoes, or peppers in the last 2-3 years to reduce disease risk.
- Work the soil deeply, breaking up any clumps. Add several inches of compost or well-rotted manure to improve fertility and drainage.
- Avoid using fresh manure or excessive nitrogen, as this can lead to lots of leafy growth but few potatoes.
The Step-by-Step Planting Process
Once your soil is workable and not soggy, you’re ready to plant. Follow these steps:
- Dig Trenches: Dig straight trenches about 6-8 inches deep and space them 2.5 to 3 feet apart.
- Place Seed Pieces: Set your seed potato pieces in the trench with the sprouts facing upward. Space them about 12 inches apart.
- Cover Gently: Cover the seed pieces with 4 inches of soil. Don’t fill the trench completely yet.
- Water Well: Give the newly planted row a thorough watering to settle the soil.
Caring for Your Growing Potatoes
Consistent care through the season is key. Your main tasks are hilling, watering, and pest watch.
Hilling: When the plants are about 6 inches tall, use a hoe to pull soil from between the rows up around the stems, leaving just the top few leaves exposed. Repeat this process every few weeks until the plants flower. Hilling protects developing tubers from sunlight (which turns them green and toxic) and encourages more potato formation.
Watering: Potatoes need about 1-2 inches of water per week, especially once tubers start forming. Water deeply at the soil level, not the foliage, to prevent disease. Inconsistent watering can lead to misshapen tubers.
Pest & Disease Monitoring: Keep an eye out for Colorado potato beetles. Hand-pick them and their orange egg clusters off leaves. Rotating your crops each year is the best defense against soil-borne diseases.
Knowing When to Harvest
You can harvest “new” potatoes carefully about 2-3 weeks after the plants finish flowering. For your main storage harvest, wait until the plants vines have completely died back and turned brown.
Choose a dry day to dig. Use a digging fork, starting far from the plant center to avoid spearing tubers. Gently lift the plant and sift through the soil with your hands for all the potatoes.
Curing and Storing Your Harvest
Don’t wash potatoes right after digging. Instead, let them cure for 1-2 weeks in a dark, well-ventilated place with moderate humidity and temps around 55-60°F. This toughens their skin for storage.
After curing, brush off any dry soil and store them in a completely dark, cool (38-40°F), and humid location. Cardboard boxes or burlap sacks work well. Check them periodically and remove any that are spoiling.
FAQ: Planting Potatoes in Maine
Can I plant potatoes in June in Maine?
You can, but only with very early-season varieties (under 70 days). Be aware that a June planting faces higher heat and pest pressure and must mature before the first fall frost, which limits your harvest window.
What happens if I plant potatoes too early?
Planting in cold soil significantly increases the risk of the seed piece rotting. A late spring frost can also burn back the tender new foliage, setting back the plants growth and potentially reducing your yield.
How do I protect potatoes from a late frost?
If sprouts have emerged and a frost is forecast, you can temporarily cover the rows with floating row cover, straw, or even newspaper. Remove the covers in the morning once the temperature rises.
Can I grow potatoes in a container in Maine?
Absolutely. Use a large container (like a 20-gallon pot) with drainage holes. Follow the same timing and planting depth, and be extra vigilant about watering, as containers dry out faster. This is a great option for smaller spaces.
What are the best storing potatoes for Maine gardens?
Mid-season varieties like ‘Kennebec’, ‘Superior’, and ‘Butte’ are renowned for their long storage life when cured and kept in proper conditions. They can often last well into the following spring.
By following these guidelines and paying attention to your local conditions, you’ll be well on your way to a plentiful potato harvest that can feed you for months. The key is patience in the spring and consistent care through the summer.