| Written by Evan Rafuse,|
KHS Landscape Professionals/Growercoach.com
Potatoes: Determinate OR Indeterminate? Plan your spring planting now!
A common question that often stumps many a gardener is, “What on earth does determinate versus indeterminate mean?” When speaking about potatoes, it can get a little confusing so let me try to make this easier for you.
It is nearly impossible to determine the difference by looking at an eye or sprout of a potato. Most, however, are determinate. Determinate and indeterminate potatoes are defined by growth patterns.
Determinate crops, tend to mean bushy in nature but restricted somehow, such as in height or cropping (single crop of a specific size).
Indeterminate, on the other hand, is the opposite: larger plants and often longer production!
Several different varieties of potato fall into each category, so there are plenty from which to choose. Select between determinate and indeterminate varieties depending on factors like yield, garden space, and amount of labor.
Whether you choose one or the other may depend on the varieties you want to grow and the potato growth characteristics might help you decide on a variety depending on how much yield you want versus how much space you have. You need more garden space to get more potatoes out of determinate varieties. For indeterminate potatoes, you will get more potatoes, but only if you have vertical space. So, hilling only benefits indeterminate varieties.
Avoid buying seed potatoes at a grocery store as they can be carriers of disease such as late blight. A great source for information on potato pests and diseases can be found on the University of Maryland Extension website: IPM * Series: Potatoes
Determinate Potatoes – fast-growing varieties with tubers that grow in just one layer – at the soil depth just above where the seed was planted! For this reason, the plants do not require mounding or hilling of the soil around them. They produce early – in about 70 to 90 days. If conditions are right, these potatoes set one layer of stolon growth that moves outward and produces up to 8 tubers. Sow determinate potatoes in loose soil to a depth of about four inches (10 cm.). Use mulch to prevent weed growth and to prevent the tubers from being exposed to the sun, which will turn the potatoes green.
Indeterminate Potatoes – Although slow-growing, continue to grow vine-like throughout the season and well into the fall. If conditions are right, a longer growing period means more stolon growth which means more tubers. That said, varieties will differ according to availability in your climate and country in which you live. You can produce crops up to 135 days out in some places! If not kept in check, the foliage can sometimes grow too much so that it impedes large, well-rounded tuber growth. You have to watch these guys. Like indeterminate tomatoes can grow out of control so can these. Indeterminate potatoes grow in multiple layers with tubers growing all along the stems where soil exists. Therefore, you should mound the soil around the plants to accommodate this and you may get a better yield. Ideally, to get a better yield for any potato you should focus on ensuring your plants have the proper soil, water and nutrients they need.
To grow these potatoes – first, cover them with 4-6 inches of loose soil. Once the plants have grown to a height of ~ 6-8 inches, add several inches of straw mulch, dead leaves and/or soil mix (hilling) until just 2 inches of the plant is sticking up from the mound or tower soil level. Continue to add layers of soil mix as the plant grows until it reaches a maximum of 18 – 24 inches. Then allow the foliage to grow and watch for the flowering stage. You will get tuber production in each layer. If you lack space, you can grow this kind of potato in towers or boxes. To ensure a good crop, do not neglect them! Pests, drought, inadequate sunlight, disease and poor soil will greatly reduce the amount and size of potatoes you harvest.
If you are expecting frost and your potato plants have not died back yet, cut the stem back about a week before the frost so that the potatoes will begin the curing process.
Container gardening will restrict the amount of space that the roots have unless the container is over 18″ in size. Many people choose to grow new potatoes in containers, and with new potatoes, it will not matter quite as much. This is because new potatoes are very small, and they will not require an immense amount of space to grow to their full potential. Therefore, you can use either determinate or indeterminate varieties of tubers for this purpose.
For full-sized, mature potatoes, you should probably opt for determinate varieties. A lot of the later season varieties tend to grow far larger potatoes with a lot more foliage. If you have excessively large containers such as totes to plant your potatoes in, the indeterminate varieties will do just fine. However, most people will grow their potatoes in small containers, such as 2 or 3 gallon fabric pots. In these instances, the determinate varieties will do far better.
A great source of information for cooking potato types: Gardeners Supply Company: Making the Most of Your Potato Harvest
There are lists of determinate and indeterminate potato varieties on the internet and in gardener-based magazines. Alternatively, visit your local nursery; they can tell you what is what. Likewise, you can easily find out what heritage varieties may be available and would grow well in your area.
Indeterminate Potatoes (Late Season)
- German Butterball
- Strawberry Paw
- Green Mountain
- Canela Russet
- Red Cloud
- Russet Nugget
Determinate Potatoes (Early & Midseason)
- Yukon Gold
- Red Pontiac
- Cranberry Red
- Russet Norkotah