Growing Potatoes

Potatoes are a crop that can be planted fairly early in the spring, and then planted in succession every couple weeks until early to mid June.

They’re unique in the sense that they grow from a piece of old potato (versus a seed - which is possible, but not done in home gardening).

Potatoes have “eyes”, which are little indentations in the skin where there’s a bud just below the surface. When exposed to warm temperatures, this eye will begin to develop and sprout - and if it has a chance, roots and leaves will begin to form at that spot.

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We can use this to our advantage when we’re planting potatoes, to get a jump-start on the season.

This process is called “chitting”, and is basically setting potatoes in an optimal environment, so they begin to develop sturdy shoots - and then plant them.

Here’s how to do it:

  • Use old potatoes from last year, or buy “seed potatoes” from a nursery

    • The difference between “seed potatoes” and “potatoes to eat” is that the seed potatoes have been tested to be free from certain potato viruses and diseases. Using eating potatoes to plant is usually fine (I’ve done this myself for years) - as long as they’re not treated with sprout-inhibitors; many grocery store potatoes are.

  • Set the potatoes on a sheet of old newspaper in a shallow cardboard box, tray, or unused counter space

  • Set the tray of potatoes in an area that is light, but out of direct sunlight

    • Direct sunlight will cause too much greening of the potatoes

    • A dark place will cause the sprouts to be too long and spindly

    • A light place will produce short, sturdy sprouts that are ideal for planting

  • If there are any long spindly shoots, carefully break them off. It’s not ideal to discard these, but the potatoes will usually re-sprout a new shoot. It’s better to discard the spindly shoots and let the potato produce better-quality shoots

  • Leave the potatoes to sprout for 1 - 3 weeks

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Once the potatoes begin to sprout, they can be planted at any time. They are usually ok to remain on the tray for up to about 3 weeks, while you wait for an ideal planting time.

When it’s time to plant the potatoes, and you have your garden area ready, you have a couple options:

  • Plant the whole potato, one potato per hole

  • Cut the potatoes into pieces, keeping an eye / sprout in each piece, and plant one piece per hole

Cutting Seed Potatoes

Cutting the potatoes is a very good way to extend your supply of seed potatoes. Small potatoes (eg 1 - 2 inches in diameter) are best planted whole, but it’s a good idea to cut large potatoes into smaller pieces.

Three notes on cutting potatoes:

  • Use a clean, sharp knife

  • Make only straight, clean cuts

  • Ideally, let the potatoes sit for a couple hours after they’re cut, so the cut surface dries out a bit before planting

The photo below shows where to make the cuts on a potato. It’s important to leave a good chunk of potato with each sprout, so that it can feed the sprout until roots form.

So, from this potato you could easily get 3 seed pieces, first by cutting on the line marked “1”, and then dividing the remaining piece of potato. This photo also shows the maximum recommended length of sprouts. If they’re kept in a light place at this stage, they won’t grow any longer, and will send out the beginnings of baby leaves and roots (which is a good thing).

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Planting Potatoes

Potatoes should be planted when the ground has dried out and is warm.

  • Dig a hole with a shovel, and place the potato in the hole, carefully keeping the sprout upright

  • Cover the potato with soil, so that the sprout is right at the surface of the soil

  • For best yields, plant each potato piece about 12 inches apart

As the potatoes grow, use a hoe or other tool to pull dirt from the pathway around the potato plant. Do this every week or two (it takes only a few minutes). With this practice, tiny weeds are automatically killed, and the extra soil around the plant helps to keep the baby potatoes covered (and therefore, they won’t be greened by the sun).

A Note on Spring Frosts

If you plant potatoes early in the Spring, such as mid-April to mid-May, there’s still a risk of frost. Any exposed part of the potato plant will be killed back by the frost. Therefore, if there’s a risk of frost:

cover the potato plant with a couple inches of soil / shredded leaves / straw / hay

OR: cover the potato plant with a large bucket or frost-protection cloth, etc

If you’re using a mulch, it can be left in place, and the potato stems and leaves will grow through it. If you’re using a bucket, uncover the plants again in the morning, when the temperature is above freezing. It’s worth this trouble on the couple of frosty spring nights to get the treat of early potatoes!

In case frost does nip the potato leaves, no worries - the plant will almost always re-grow from the root.

Watering Potatoes

Potato plants do best with a consistent drench of water every week.

However, they will also produce quite well without this weekly soak… as long as they get a good drink of water at a couple of key point.

Here’s when to make sure they get extra water:

  • When the plants have sent up a few stems, and are rapidly growing (this is when they’re setting the number of baby potatoes underground)

  • When the plants are in flower (this is when the potatoes are starting to size up)

Feeding Potatoes

Potatoes will do well with compost worked into their planting area, or feed the soil with diluted fish emulsion.

They are heavy feeders in the sense that: the more nutrition that’s available to them, the healthier they’ll be , and the more productive they will be.

Therefore, they respond well to extra feedings of fish emulsion, especially at the times noted above for extra watering.

If potato bugs appear in the summer, spray the plants with a nutritive foliar spray. This can help raise the Brix (sugar levels) of the leaves, which in turn repels the bugs.

Mulch

Potatoes love mulch.

There are a few options for mulching potatoes; just use whatever you have available.

The benefits to using mulch for potatoes:

  • the soil stays moister

  • the soil stays cooler

  • weeds are minimized

  • no need to hill up soil around the plants - the mulch has the same end result of protecting the baby potatoes

  • harvesting is easier, and the potatoes will generally be cleaner

You can use straw, hay, shredded leaves, or even sheets of plain cardboard, cut to fit around the plants.

Landscape Fabric

One type of mulch I use is landscape fabric. This is useful when a person doesn’t have enough straw / leaves, etc around, and the potatoes grow very well with it.

I plant them 12 inches apart in the row, with 3 rows together that are 12 inches apart. In other words, a pathway every 3 rows.

If you’re using landscape fabric, I would suggest applying a bit of mulch in the planting hole, once the plants are actively growing. This will minimize any greening of the potato that grows closest to the base of the plant.

New Potatoes

If you can’t wait for the first taste of potatoes in the early Summer, you can “steal” a couple from under each plant. Simply scoop some dirt away from the side of the plant, being careful to disturb the roots as little as possible. Feel around for a large potato, and pull it out.

You’ll likely see lots of tiny potatoes connected to the mother plant; leave them alone, re-cover with soil, and they’ll grow into big potatoes!

Curing Potatoes

If you’ve planted lots of potatoes, and want to store some for the winter, then wait until the plants naturally die back before harvesting them. The potatoes can be kept in the ground for a couple weeks, and this will help harden the skins so that they will keep better in storage.

Use a shovel or digging fork to dig up each hill of potatoes, being careful to start digging at least a foot away from the plant, so that you don’t spear any potatoes.

Set the potatoes in a single or double layer in the shade for a day or two, so that any dirt will dry on them, and can easily be brushed off.

Set aside any damaged potatoes to use right away.

Store your potatoes in a breathable container, such as a vented cardboard box or burlap bag, in a dark and cool place - and enjoy throughout the fall and winter months!