• Krista Green

Growing Potatoes - Determinate vs. Indeterminate Varieties

Updated: 3 days ago

Whether you have been growing potatoes for years or are a beginner gardener understanding the difference between determinate vs. indeterminate potatoes can save you time and effort and give you a better potato crop! Today we will discuss some tips to help you get the best yield possible out of your potato crop and to increase your confidence as a knowledgeable potato gardener.

Determinate red pontiac garden potatoes being dug out of a raised bed in a backyard, vegetable garden in gardening zone 3 Alberta, Canada.

The Ideal Soil For Growing Potatoes

The first thing you want to take a look at when growing potatoes is your soil. Potatoes prefer slightly acidic soil, with a pH between 5.5 - 6.5. You may want to pick up a soil testing kit. These can often be found at hardware stores that carry gardening supplies. If you are like me and have highly alkaline soil (mine is a pH of around 8.5 - 9) you may want to do some amending prior to planting. (Check out my post on Improving Your Garden Soil.) Mixing organic matter such as compost, mulch or peat moss into your existing soil are some easy ways to begin adjusting soil pH and improve soil quality. The best time to start this is in the fall but if you are beginning in the spring it is not too late and can make a big difference in your potato yield.

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You may also have soil with a high clay content which will hinder your potato growth and yield. Adding in organic matter will go a long way to creating a nice loose soil with good drainage. Sand, as a soil amendment for clay, is controversial. It is difficult to add enough to actually make a difference and another problem with sand is that there is no nutritional benefit to it. Some believe adding sand to clay soil creates a concrete type mixture but there in little to no strong scientific evidence supporting this. For these reasons, adding organic matter is a much better option.

If you chose to add wood ash to your compost or garden, do so with caution as it can cause scabby potatoes.

Another thing worth mentioning is that too much fresh compost may work against you when it comes to potatoes. Compost is high in nitrogen. High nitrogen levels can send too much potato tops, causing them to grow beautiful leaves and spending little time growing the tubers underneath. For this reason don't add compost to your garden potatoes after planting.

Types of Potatoes - Determinate vs. Indeterminate

Not all potatoes grow up the stem creating all those vertical layers in the potato bag or large container that you may have seen pictures or videos of. With this deep container idea you add soil to your potato throughout the growing season and when you harvest, hope to have multitudes of potatoes! Did you know that hilling your potatoes may not actually be necessary?

There are two main types of potatoes, determinate and indeterminate. What is the difference you ask? Let me explain.

Potato blossom from a determinate potato in my backyard raised bed vegetable garden in zone 3 Calgary, Alberta.
Potato Blossom

Determinate potatoes are fast growing (this is why they are the more common variety for my Alberta, zone 3 growing zone) and their tubers grow in only one layer. This is why hilling determinate potato varieties does not impact your yield. You do not want the growing potato tubers exposed to sunlight as this will turn them green. Adding mulch or hilling them once, although not altering the yield, will ensure they don't end up green. Determinate potatoes also produce earlier than the indeterminate varieties - a big plus for those gardening in the cooler zones.