What Is a Determinate Potato? Early Season Types
A determinate potato is a garden term, not an official class, for a variety that sets tubers in a single layer. Ask Extension experts note potatoes are usually classed as early, mid or late season. Early season varieties have a determinate habit and only need about 4 to 8 inches of soil cover.
The short answer
A determinate potato is a garden label for early season types that set tubers in one layer near the seed piece. Ask Extension experts note potatoes are formally grouped as early, mid or late season. Early types need about 4 to 8 inches of soil cover. Late types are indeterminate plus need more hilling.
Where does the term determinate potato come from?
Ask Extension experts note there is a lot of confusion about the terms. Seed suppliers rarely label potatoes this way, and no official list exists. Gardeners borrowed the words from tomatoes.
| Season group | Garden term | Soil cover |
|---|---|---|
| Early season | Determinate | About 4 to 8 inches |
| Mid season | Either | Check plus add soil |
| Late season | Indeterminate | Tubers within a foot of soil |
Source: Ask Extension.
How do early and late potatoes differ?
Ask Extension experts note early types bloom sooner than late types. Late types grow tubers along the stem within a foot of soil. In short seasons, late types may not ripen in time for storage. Purple Viking is listed as mid season at 80 to 110 days.
Do determinate potatoes need hilling?
Ask Extension experts note early types only need about 4 to 8 inches of soil cover. University of Minnesota Extension advises hilling when stems are about a foot tall plus once or twice more. Hilling stops tubers from turning green in light.
How to: step by step
- Check whether the variety is early, mid or late season.
- Buy certified seed tubers.
- Plant when the soil reaches 50 degrees F.
- Space seed 8 to 12 inches apart.
- Hill once stems are about a foot tall.
- Harvest after the tops die back.
Troubleshooting
Green tubers: light reached them. University of Minnesota Extension notes hilling stops greening.
Knobby or hollow tubers: moisture was short early on. Water evenly during early growth.
Late types not ripening: the season is short. Choose early or mid season varieties.
For related reading see life cycle of a marijuana plant, fabric pots for cannabis plus raised beds for cannabis. Kind Seed Co also stocks cannabis seeds.
Sources
- Indeterminate or determinate potato varieties?, Ask Extension (Cooperative Extension network)
- List of determinate vs indeterminate potato cultivars, Ask Extension (Colorado State University Extension Master Gardener)
- Growing potatoes in home gardens, University of Minnesota Extension
- Potato facts: growing potatoes in the home garden (Bulletin 2077), University of Maine Cooperative Extension
FAQ
Is determinate an official potato class?
No. Ask Extension experts note there is no official list of determinate potatoes. Seed suppliers rarely describe varieties as determinate or indeterminate. Potatoes are usually classed as early, mid or late season. The determinate label is a garden shorthand for early types.
Which potatoes are early season?
Ask Extension experts note early season varieties have a determinate habit plus bloom earlier. They name Purple Viking at 80 to 110 days as mid season plus German Butterball at 100 to 130 days as late season. Check the days to maturity on the seed label to place a variety.
When should potatoes be planted?
University of Maine Cooperative Extension advises planting as soon as the soil warms to 50 degrees F. Seed sitting in cold wet soil can decay. University of Minnesota Extension advises planting tuber pieces as soon as the soil warms, which is early April in the Twin Cities area.
How far apart should seed potatoes go?
University of Maine Cooperative Extension advises 8 to 12 inches between seed pieces in the row plus 30 to 36 inches between rows. It advises a furrow four to six inches deep with two inches of soil over the seed at first, then hilling as the plants grow taller.
Why do potatoes turn green?
University of Minnesota Extension notes green skin forms when tubers are exposed to light. Hilling soil around the plants stops shallow tubers from greening. After harvest, University of Maine Cooperative Extension advises getting potatoes out of the light plus storing them in a cool, dark place.
