Potato Grow Bag Size | Get The Harvest Right

The best potato grow bag size for most home gardeners is 10 to 15 gallons, with 15 gallons providing the ideal balance of yield and manageability.

Choosing the right potato grow bag size comes down to how many seed potatoes you want to plant and how much harvest you expect. A bag that’s too small crowds the roots and shrinks your potatoes, while an oversized bag becomes heavy and hard to manage once filled with soil. The sweet spot for most home growers is a 10–15 gallon fabric bag.

Why Bag Size Matters For Potatoes

Potatoes need two things from their container: enough root volume and enough depth for hilling. Hilling is the practice of adding soil over the stems as the plant grows, which encourages more tubers to form along the buried stem. A wide but shallow bag won’t give you the vertical room this process needs.

Depth matters as much as capacity. Most experts recommend a bag that is at least 12–14 inches deep. The best fabric bags are typically 40–80 liters, with 50–60 liters (roughly 13–16 gallons) offering the best balance of soil volume and manageable weight. Look for a bag at least 45 cm deep, with 50–60 cm being optimal.

Bag Size vs. Seed Potatoes: A Quick Guide

The number of seed potatoes you can plant depends directly on the bag’s volume. Overcrowding is the most common mistake — it leads to smaller tubers and a disappointing harvest. Here’s a practical guide based on what works in real gardens:

In practice, a 10-gallon bag typically yields 5–10 lbs of potatoes, while a 15-gallon bag can produce 7–13 lbs. If you want a genuinely large harvest, some experts suggest going up to 25 gallons minimum — but remember that a filled 25-gallon bag of soil is very heavy and hard to move.

How To Plant Potatoes In A Grow Bag

Start with a breathable fabric bag that has drainage holes. Avoid plastic tarp-style bags unless you can punch adequate drainage yourself — waterlogged soil rots tubers quickly.

1. Roll the bag sides down to about one-third of their height.
2. Add a 10 cm (4-inch) base layer of compost or potting soil.
3. Place 3–5 chitted (pre-sprouted) seed potatoes on top, eyes facing up, spaced evenly across the surface.
4. Cover them with 8–10 cm (3–4 inches) more compost.
5. Water thoroughly so the soil is evenly moist but not soggy.

As the shoots grow to about 8 cm (3 inches) tall, add another 10 cm of soil over the stems. This is the hilling process — repeat it as the plant grows until the soil reaches the top of the bag. Keep the soil consistently moist; fabric bags dry out faster than ground soil, so check them regularly during hot weather.

Once your plants flower and the foliage starts to yellow, your potatoes are ready to harvest. Simply tip the bag onto a tarp and dig through the soil with your hands.

If you’re ready to start your first grow-bag crop, our tested roundup of the best potato growing kits covers the bags, tools, and seed potato options that performed best in our trials.

Common Bag Mistakes To Avoid

Most grow-bag failures come down to a few avoidable errors. Choosing a bag that is too small for the number of seed potatoes is the biggest one — overcrowding reduces both tuber size and overall yield. Ignoring depth is another; potatoes need vertical room for roots and hilling, not just surface width.

Using a bag without proper drainage is a sure way to rot your crop. Breathable fabric bags or obvious drainage holes are non-negotiable. And don’t forget to hill — exposed tubers turn green and bitter from light exposure. Finally, avoid buying an oversized bag without thinking about weight;

The right bag size also depends on what you’re growing. Early and salad potato varieties do fine in smaller bags, while maincrop varieties that need more time and space benefit from 15 gallons or more. When in doubt, err on the larger side — the extra soil volume gives you more room for hilling and a bigger harvest.