Potatoes are easy to grow and can be grown in a variety of ways, even in containers. They are a great vegetable to grow for complete beginners and, of course, you can enjoy the end product on your dinner table. In this article, we are going to cover how to grow potatoes, when to sow them and share a few tips and tricks to produce a high yield when it comes time to harvest.
What Are Seed Potatoes?
When you come to buy potatoes you buy seed potatoes. They are not seeds in the sense of a flower that has produced seed, although potato plants can flower and produce seed (known as true potato seed).
Seed potatoes are a tuber grown with the purpose to be replanted. They look similar to normal potatoes but unlike normal potatoes are guaranteed to be disease and virus free.
You will notice that if you leave potatoes too long they may develop sprouts. It is these sprouts that will eventually grow into the plant. If you planted your cooking potatoes they will grow but could be affected by blight or other diseases.
Types of Seed Potato
Depending on the time of year and the variety of potato, generally, either waxy or floury types of potatoes will determine the type of seed potato to plant. There are the following categories of seed potatoes:
First Early Potatoes
These, as the name suggests, are the first type of potato to be sown in the year and the first to crop. First earlies are sown straight into the ground a few weeks before the first frost. Most first earlies will be able to be harvested around 10 to 12 weeks after sowing which is really quite quick. First early are usually a waxy potato or new potato with soft thin skins.
Second Early Potatoes
Second earlies are sown 2 or 3 weeks after first earlies and produce a similar type of potato but take a little longer to crop. Second early potatoes are harvested after around 3 months.
Maincrop potatoes tend to be the types of potato good for mashing, baking and roasting. They take the longest amount of time to crop and are usually harvested after about 16 – 22 weeks. Maincrop potatoes are sown just after the last frost as tender shoots will be frost damaged.
The Best Time to Plant Potatoes
Potatoes are one of the first crops that can be planted every year in Northern regions, which often leads them to be able to produce more than one crop. Potatoes that mature early can be planted just before the last frost is over, with some regions able to plant as soon as March or April when the soil is workable.
If you decide to plant early and a frost comes, or temperatures overnight are chilly, you’ll need a good ground covering of mulch to keep the soil warm. Frost protection fleeces or sheets can also be spread over the top of potato beds to prevent frost from damaging plants.
For best results and less chance of frost damage, wait until a week or two after the last frost when temperatures are staying above freezing throughout the night and increasing as we draw closer to summer.
The temperature of the soil should be around 10°C / 50°F and moist but not muddy when planting. If your area has had a lot of rain in recent days, wait until the soil has had a chance to drain before planting.
Preparing the Potato Beds
Before planting your potatoes, there are a few things you need to know about growing conditions that are ideal for sowing potatoes.
- Potatoes are a full sun crop that requires at least 6 hours of sunlight each day
- Rows should be 60cm / 2 feet apart for early varieties and 75cm / 2.5 feet for maincrop varieties.
Potatoes are best sown in trenches. If you’ve never dug trenches before, follow these guidelines:
- Planting should be done in trenches 15cm deep and 15cm wide but tapering down to “V” at the bottom. A round-point shovel or garden hoe is perfect for this task.
- The bottom of the trench should be filled with organic compost or a garden-top soil mix from your local garden centre.
Planting Potatoes in Trenches
Planting potatoes in trenches is straightforward. All you’ll need is seed potatoes to get started after your trenches are ready.
- Seed potatoes have eyes with small shoots sprouting from them. These should be pointing upwards. If the seed potatoes are larger than a golf ball you can cut them in half ensuring there are eyes on both halves, plant both halves to boost your yield.
- Wait for one to two days before planting cut seed potatoes so the cut side of the potato can heal and have better moisture retention.
- Place the seed potatoes roughly 30cms / 1 foot apart. Cover the potatoes with three to four inches of soil.
After planting the potatoes, you’ll need to keep the soil moist. The trenches will not be all the way filled at this point, and that is okay. After 12 to 16 days, you should begin to see sprouts shooting up through the soil in the trench. You’ll fill the trench with another 3 to 4 inches of soil. Make sure always to leave a few inches of the sprouts exposed as you begin this hilling method.
How To Hill Or Earth Up Potatoes?
Hilling up potatoes is the process of keeping the potato plants underground as they grow where temperatures remain consistent. Every few weeks as the sprouts get taller, fill the trench with another few inches of soil until you’ve created a mound or hill that is about 5 inches above the ground.
When you hill up potatoes in this way it allows more potatoes to grow above potatoes already formed below. This maximises yield and produces better potatoes as they have more consistent temperatures and space to grow.
Tubers are sprouts that form on secondary stems that branch off from the main stem that flowers above ground.
While these tubers usually stay underground, shallow ones can be exposed to sunlight still and produce a chemical making the potatoes green and mildly toxic.
Tubers are important for potatoes to flourish and produce a large yield. To encourage tuber growth without being exposed to sunlight, the dirt and compost are hilled up in the trenches.
Plants are tallest in the morning sunshine, so make sure to do the hilling process early if possible. Make sure to do a final hilling right before the plant blooms above ground. This usually happens once the plant is 12 inches or so above the trench.
Potatoes can be harvested within 2 to 3 weeks of the plant flowering if they are new potatoes. They will only keep for a few days, so they need to be uncured and eaten quickly.
Mature potatoes should be harvested 2 to 3 weeks after the plant has begun to die back. The flowering heads should be completely gone before cutting the foliage.
Once the foliage is cut down, you’ll wait another two weeks to allow the potato skin to thicken before digging them up. Do not water the potatoes after August to keep the soil dry and toughen the potatoes. If your soil is moist, consider digging up the potatoes after 7 to 10 days to ensure they do not rot.
Dig up one hill of potatoes as a test. If the skin of the potatoes rubs off easily under your thumb, the potatoes are not mature enough yet, and the rest of the crop should be given a few more days. Ensure you don’t leave dug up potatoes in the sun; otherwise, they will turn green and produce the toxic chemical solanine.
Common Pests & Diseases For Potato Crops
Potatoes need more than hilling and great soil to have an excellent yield. There are a few pests and diseases potatoes are susceptible to that you need to be aware of and on the watch for.
Potato Scab is a common potato disease that causes misshapen spuds with corky spots. Potatoes with thin skin are more at risk for this disease that also affects other root vegetables. Potato Scab is caused by bacteria in the soil called S. scabies.
These potatoes are still edible as the disease only affects the skin and, once peeled, will look, feel, and taste like an ordinary potato. Many growers choose to discard of crops affected by potato scab because they are harder to sell to retailers.
Potato Blight presents as dark spots on the leaves of the shoots. Once the spots appear, the plant will collapse, and potatoes will rot in the ground. This disease is persistent and can spread quickly through a potato crop to affect all your plants.
Pests that like to invade and destroy potato crops include beetles and aphids. Unless heavily covered aphids and beetles are usually harmless but you may wish to treat the plants if they are overrun.