Watering Potatoes: Best Practices for a Healthy Harvest

Potatoes are a delicious part of most gardeners’ diets. They’re tasty no matter how you eat them – baked, fried, mashed, or stuffed, with or without a big pat of butter. And if you know how to care for them correctly to set them up for success, they can be easy to grow in your home garden. 

Once they plant potatoes, many gardeners have questions about the best practices for watering potatoes. Like all vegetables in the garden, potatoes do need a regular supply of water throughout the growing season to ensure an abundant harvest.

How and when to water depends a lot on the climate in which you live. In general, most vegetable plants need 1 inch of water per week. I’ve written an extensive article with lots of details on watering your vegetable garden.  Here we’ll cover watering potatoes specifically. 

When and How Often Should You Water Your Potato Plants?

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Potatoes like consistent moisture throughout the plant and tuber growth period. But, they don’t like to grow in soggy or extremely dry soil, so watering is a balancing act.

Ideally, do not let the soil dry out completely between waterings. Watering potatoes too little later in their life cycle often results in a smaller harvest. I don’t advise watering every day either, since potatoes could rot if they’re sitting in wet soil. 

If you have very sandy soil or your area is going through an extremely hot or dry period, you can water a couple times a week if you find the soil is drying out quickly. This is less of an issue when the potato plants grow bigger because they tend to help shade the soil, retaining moisture. 

Again, approximately one inch of water per week is ideal.

In my garden, I keep a mental note throughout the week how much rain has registered in my gauge and water on Monday if necessary.

If it rains an inch or more throughout the week I usually choose not to water my garden that week. You can always dig down into the soil a bit with a trowel to discover how much soil moisture is still present.

One thing I’ve realized over the years is that I have no concept of how much water a rain event brings. That’s why a rain gauge is a more reliable measure of how much rain your garden actually received. Don’t rely on your “sense” of how much it rained, gather the actual data instead.

Here are some options for simple rain gauges. I like plastic over glass because the glass versions break very easily. I prefer taller gauges that won’t get covered up by the plants around them later in the season.

World’s Coolest Rain Gauge

Metal and Glass Rain Gauge with Solar Powered Light

Jumbo Rain Gauge

Large Easy to Read Acrylic Rain Gauge

What’s the Significance of a Potato Flower?

Potatoes are in the Solanaceae, or nightshade family, along with tomatoes, peppers, tomatillos, and eggplant. Eventually, when your plants have gained significant growth, you’ll notice the plants starting to flower. The flowers can be found on the tips of the plants and range in color from white, to pink, to purple depending on the variety you’ve planted. If you’ve grown other vegetables in the nightshade family, you’ll be able to the similarity between their flowers and potato flowers. 

The potato flowers are a sign that the plant has started to produce tubers underground. The bees and other pollinators love making visits for pollen, so you can just leave the flowers for insects to enjoy them.

Sometimes, if the flower is pollinated, it will produce a small fruit that looks like a green tomato. These are poisonous (remember the Deadly Nightshade from Roman Times?) and filled with seeds. Just leave them on the plant and make sure children and pets aren’t picking them.

Usually around the time my potato plants are flowering, I’ve hilled them as much as I can. At this time, I mulch them heavily with hay or straw and continue to make sure they receive 1 inch of water per week until close to harvest time.

How to Harvest Potatoes

Potatoes are a great crop because they have pretty clear signs when it’s time to harvest. Eventually, the tops of the plants will start to turn brown and die back. Don’t be concerned! This is a natural part of the potato growing process. 

Timing
Once the plants completely die, make a note of the date. You’ll want to let the potato cure underground for about two weeks before harvesting. This allows the skins to toughen up so they’re not so tender when you’re digging them up.

You can also stop watering potatoes at this time.

If it’s late in the season, you’ll need to make sure you harvest the potatoes before it frosts or they may get mushy. If you’re coming up on the average date for your first frost and the plants haven’t started to die back yet, chop them down onto the bed to encourage the tubers to harden their skins. 

Tools for Harvesting
My favorite tool for harvesting is a digging fork. I not only have one, but two digging forks hanging in my garage I love them so much.

I use it for loosening up weeds so I can pull them out by the roots, harvesting carrots, potatoes, and garlic, and breaking up clods of my clay soil before planting. I have this exact one from Fiskars, which is a local Madison company.

Technique
This is the point where you have to be very careful! It’s so incredibly easy to spear the potatoes while harvesting. My technique is to stick the digging fork into the soil a few feet away from a dead plant. I use it to gently loosen the soil around the plant and start to sift the soil looking for potatoes. 

I’ve never harvested a bed of potatoes without spearing at least a few of them, so don’t get too upset if that happens. You can put them aside to eat sooner than later.

Keep digging around the bed until you think you’ve found most of them. It is hard to get every single one potato out of the garden bed. It’s common the next spring to see new potato plants sprouting out of the garden bed in which they were planted the previous season. 

Washing
I prefer to wipe my potatoes when harvesting to knock as much soil off of them as possible. If you only have a small amount of potatoes and you think you’ll eat them in the next several weeks, you can wash them off with a hose or in a bowl in your kitchen sink. Let them air dry overnight before moving them into a cabinet or pantry.

If you’ve grown a larger amount of potatoes and you want to store some of them for winter meals, you’ll need to cure them.

Curing Potatoes for Storage

I don’t like to wash my potatoes if I’m planning on storing them for winter. Instead, I try to knock as much of the soil off as possible. I line shallow bulb crates with newspaper to catch any soil that may fall off over time and spread them out in a single layer to store them.

Ideally, potatoes are stored in a dark, cool place at about 40 degrees F. I have a dark closet in my basement that stays very cool in the winter which I use as my storage area. Some gardeners store their potatoes in the fridge. 

I find that potatoes are one of the lowest maintenance vegetables in the garden. Planting, hilling and mulching are all very simple tasks, and as long as you know the ins and outs of watering potatoes you should be rewarded with an abundant harvest. 

Next Steps for Getting the Most Out of Your Garden

MASTERCLASS: Success in Every Season – Each season we’ll focus on exactly what you need to know to be successful in that season. The seasons build upon one another (just like in your garden!) to create a complete toolkit of skills that will set you up for a lifetime of gardening. Find out more here.