How to Grow Potatoes in a Grow Bag

The first spring we farmed in New Hampshire, we excitedly planted several beds of potatoes. What followed was an extremely cold and wet spring that bled into summer, resulting in sad and soggy plants. We were forced to harvest tiny potatoes before they rotted in the ground. Our haul may have been smaller than the amount we purchased in seed potatoes. But alas, the farmer pushes onward! 

It was intimidating to try again after that year, but with each year of experience, no-till practices, and improving our soil fertility, the pest pressure diminished, the plants thrived, and we learned from common mistakes. Eventually, we successfully grew them. 

Step 1: Gather Supplies

Getting started is easy. Let’s grab the supplies you’ll need. 

• Seed potatoes. These serve as the “seed” when starting new potato plants.
• A clean knife
• Potting soil: This should be a rich, well-draining soil.
• Optional compost to mix into potting soil 
• Grow bag (s): If you’ve used these before, clean old debris out and sanitize them by soaking them in a 2:1 ratio of water to 3% hydrogen peroxide for 20 minutes, then rinse them thoroughly. 
• A trowel for planting, hilling, and later, harvesting. 
• Access to clean water

Step 2: Select the Right Spud

Different types of potatoes are best for different culinary uses, so pick one that suits those needs. Here are a few popular types and what they’re commonly and best used for: 

• Russets (starchy): baking, mashing, and frying 
• Red potatoes (hold up well when cooked): potato salad, soups, stews
• Yukon gold potatoes (soft, creamy flesh, good all-purpose potato): boiling, baking, frying, mashing, roasting
• Fingerlings (waxy, tubular, keep their shape): grilling, pan-frying, roasting 
• Blue potatoes: use them in stand-out dishes to highlight the color 

Pro tip: If your season is short, look for varieties that mature in 80-100 days.

Step 3: Preparing and Planting Your Potatoes 

You can propagate potato plants by seeds, but the most common way is to plant tubers. These will create an exact clone of the parent plant. 

Depending on your growing region, potatoes can be planted in the ground any time from January to mid-April after the risk of frost has passed. However, when planting them in grow bags, you can start a little earlier than you would outside in garden soil. If you can place the bags in a warm greenhouse or a semi-heated garage or basement, they’ll get a little head start. 

Due to their long time in the ground (90-120 days), plant them before the heat of summer kicks in for best success. Young plants won’t develop properly if temperatures are too hot.

Preparing Seed Potatoes 

If the potatoes you purchased for seed are whole, you may choose to cut them into smaller chunks, about two inches each, before planting. This process is called “chitting,” and it allows you to get more bang for your buck. It’s also a pre-sprouting process that some growers claim results in larger yields. When you choose to chit your potatoes, they must then dry before planting to prevent pests, pathogens, and rot. 

Each seed potato piece should have 1-3 eyes. Each eye will form sprouts and roots, growing toward the sun. If the seed potatoes are already cut, simply gather them up and get ready to plant them. 

Preparing Grow Bags and Planting 

Fill your bags with four to six inches of moistened soil mix, sprinkling in a bit of compost if desired. Tamp the soil down by picking up the bag and dropping it down gently.

Then, using your hand or trowel, create holes for each seed potato, placing it just below the soil surface, sprouted eye side facing up. Cover the potatoes with two to three more inches of soil. Water the spuds and let them be for a few weeks. 

Spacing

When planting in the ground, it’s recommended to give each potato plant about 16” of space on either side. When using grow bags, ensure the roots have enough room to spread out and develop a full-sized tuber. Depending on the variety, a 5-gallon bag can accommodate one to two potato plants, and a 10-gallon bag can accommodate four to six. 

Step 4: Location, Location, Location! 

Potatoes need lots of sun, so position them in a place where they’ll receive at least 6 to 8 hours of sunlight a day, but they can handle a spot that offers no shade at all. Ensure easy access to water.

Drip irrigation with tubing is going to work best for potatoes. When grow bags are placed in line, you can efficiently set up an irrigation system right across them. 

Step 5: Caring For and Monitoring Potatoes 

Potatoes prefer to mature and perform their best in cooler temperatures. If you live in a warmer growing zone, try covering them with shade cloth to improve performance in hot spells. 

Weeding

Weeds are much easier to manage when growing in bags and are less prevalent, but an important step for keeping potato plants healthy. If you allow weeds to prevail, you’ll just be feeding and caring for them, taking away important resources from your potatoes. 

Pests

One of the worst potato pests is the Colorado potato beetle (CPB). It has become almost fully pesticide-resistant, and if left alone, it will destroy your whole patch. Know what to look for and scout early. When potatoes are first planted, cover your bags with insect netting for protection until the plants grow too tall.

You could even insert small hoops to allow the netting to stay on longer to keep adult beetles from laying eggs on your plants because, at that point, you’ll have a big problem. Like other spring pests, if they can’t find the food they like in your garden, they’ll simply move to another area to lay their eggs. 

Other pests include aphids, flea beetles, and the potato tuber moth. 

Fertilizer

Potting soil has a generalized amount of nutrients to get seedlings started, but since potatoes are in the ground for so long, they’ll benefit from an application mid-season. While they don’t typically need a whole lot of fertility, adding something with equal parts potassium and phosphorus won’t hurt. Nitrogen is important during vegetative states, but you should back off from it when the tuber is forming underground to avoid too much above-ground green growth. 

A mid-season feed may increase the size and yield of your potatoes. You can also use a balanced slow-release granular feed about four weeks after planting. Pro tip: Applying foliage phosphate in addition to fertilizing the soil should increase yields. 

Hilling Up Potatoes 

Hilling is crucial to allow tubers more space to grow. When planting potatoes in a bag in just four to six inches of soil, they’ll be pretty low down in the bag, giving you lots of space to build up. Once there are about eight inches of foliage above the soil surface, it’s time to hill. This should be repeated each time the foliage reaches this height to continue proper tuber formation and growth. 

The built-in benefit of growing potatoes in bags is when you first plant them. You can roll the sides of the bag down to ensure newly sprouted plants get enough sun. As the foliage grows and the tubers require more growing medium, simply roll the sides up, add about six inches of soil over the canopy, and fertilize. Any buried foliage will produce more potatoes, and the additional soil may prevent pests from prevailing, retain moisture, and decrease the weed seed bank.

Step 6: Watering

As with most crops, water them right away after planting them. As they settle in and start to sprout, they’ll require about one to two inches of water per week. One of the best things about growing in fabric grow bags is they’re virtually impossible to overwater! If you have ensured your soil is well-draining and composted, any excess water will easily drain out rather than pooling at the bottom of the bag. 

Excessive moisture can lead to fungal disease and root rot, so this feature of fabric grow bags is a big one. When I was a new grower, I tended to overwater. That’s not uncommon. I think, in general, we growers tend to think more water is better than risk our plants having too little, but you can do a lot of damage by overwatering. 

During especially hot, sunny spells, check your grow bags daily for moisture levels. 

Step 7: Harvesting 

It takes between 90-120 days for potato tubers to properly grow and mature. At this point, tubers are full-sized and starchy. Digging them up is SO fun for adults and kids alike. Let’s learn more about when and how to harvest. 

When Are Potatoes Ready to Harvest?

The foliage above ground will give clear signals that let you know the tubers are ready for harvest. The leaves will begin to yellow and die back, letting you know the plant has used up all its energy to form the tubers. 

How to Harvest 

When growing in grow bags, it’s easy enough to simply pull the entire plant right out of the container to harvest. Alternatively, you can cut leaf debris out of the way and dig around using your hands or a trowel or simply tip the bag over. Be careful if using a tool that you don’t damage the potatoes below.

New Potatoes 

Many growers choose to harvest some of the same varieties you’re growing for full-size or storage potatoes early as “new potatoes.” This term simply means young, small potatoes. This method allows farmers to bring an early crop to market and offer a sweet, tender-skinned version of their older counterparts that will be available later in the season. It also gives them a longer harvest and selling period. New potatoes can be harvested two to three weeks after flowering has finished. 

Don’t wash new potatoes until you’re just about to use them because their skins are so thin that you could damage them if they’re processed too heavily. While these won’t last very long in storage, they’re a delicious early-season treat, perfect for tender potato salad, steamed as a side dish, or mixed in with early summer squash, baked into a torte. 

Storage Potatoes 

Keeping some dirt on potatoes before storage will give them the longest possible shelf life. Place potatoes in a well-vented box or bag without over-crowding them. Store them in a cool, dry area for up to several months. Refer to variety-specific information for the exact length of possible shelf life. Storage potatoes should be harvested one to three weeks after the foliage has died back. 

Frequently Asked Questions