How to Grow Potatoes

HOT TIP: They need their own space & there's still time!

Potatoes are one of the most often requested vegetables when I first meet with clients, and they're a great crop to grow if you have limited space or sun exposure. Potatoes need their own place to grow - they are prone to soil disease, they take over a garden AND inevitably you’ll leave some potato behind and they’ll just come back next year! I treat potatoes like a perennial plant and keep them OUT of my annual, rotating crop beds. You can build a separate potato cage in your yard or parking strip, or you can try growing them in potting soil bags. You can build a special “potato box” or you can use an old garbage can - many options!

How Potatoes Grow

Potatoes are a 'tuber', an underground, fleshy stem bearing buds that eventually turn into the potato that we harvest. (Jerusalem artichokes aka sunchokes are tubers, too. Dahlias are also tubers.) After planting, potato seed (a small cut-piece of a potato with a sprouted 'eye') will put on top growth - the leafy part of the plant that develops about 4 weeks after planting. This leafy bit produces leaves and flowers. As the plant stem grows, they produce energy for the plant and this energy is then stored in the 'tubers', which we call potatoes!

How to Plant & Cultivate Potatoes

The strategy for growing potatoes is to cultivate a healthy environment so that each stem produces as many tubers as possible. To do this, after some stem and leaves develop, we slowly cover the plant stems. You can do this a few different ways.

Cover stems with a dense layer of hay mulch - this helps to hold in moisture and also creates a clean growing medium for the tubers. When mulching, aim to leave about 3 to 4 inches of stem exposed and add hay as needed.

You can also do this using a more traditional method of “hilling”. To plant, dig a trench 4-8” deep. Plant potato seed & cover. Once stems reach about 4” of height, cover them with soil, leaving the top green leafy tips exposed. Keep filling the trench as the plant grows. Eventually, you will also “hill up” soil around the stems, allowing more tubers/potatoes to be produced.

Just-filled potato trench & exposed stem structure

I've tried both hay and hilling over the years and like them equally. In some gardens, I use hay. In others, I’ll hill with soil. Hilling is pretty farm-y, but can be difficult for urban farmers with limited space.

I've successfully grown potatoes in a soil bag on my apartment garden deck, in burlap bags at a client’s garden and in trenches when I have the space. Erica over at Northwest Edible Life (and author of The Hands-On Home), posted about building potato cages many years ago (tall planters made from cementing mesh and landscape fabric) and I really liked that growing environment, too.

To build a potato cage, you essentially make circular beds with strong, wire fencing and line them with landscape fabric to hold in the soil. You can line them with any material that won’t break down in sun and with constant watering. I’ve used cool looking vintage feed bags, but landscaping fabric also works well and looks decent. I have yet to find a potato cage lining that looks fancy and ‘clean’, but I also don’t spend a lot of time worrying about how a production garden looks, soooo……if you have any ideas or have used something in the past that you love, please let us know in the comments.

When to Plant Potatoes

Potatoes can go in the ground as early as mid-March and be planted anytime through mid-June. Anything later is too late.

After about 4 weeks and 4” of growth, start filling the trench with soil. Once filled, continue hilling up OR covering the plant stems with hay mulch for another 4 weeks or so. Aim to bury about 8” of stem in total.

Fertilize potatoes when you first plant them and again 4 weeks later. Sprinkle a small handful of all purpose fertilizer around each plant and fork it into the soil. You may also use a liquid fertilizer, if you prefer.

Harvest

Potatoes are ready to harvest about 60 days after sowing OR when the tops of the plants turn brown and die back. Remember to keep ALL vegetable beds consistently watered, and you’ll have handfuls of new potatoes for summer-eating by July.