Potatoes Small: Spacing, Water and Early Harvest
Potatoes small at harvest usually trace back to close spacing, early dry soil or digging before the vines finish. The University of Minnesota Extension says to space seed pieces closer for smaller tubers and farther apart for fewer but larger tubers. It adds that dry soil in early growth can stop new tubers from forming.
The short answer
Space potatoes wider, water evenly while tubers form and wait for the vines to dry before digging. Maryland Extension spaces plants 9 inches apart for new potatoes and up to 20 inches for large storage potatoes. Minnesota says new potatoes come about seven to eight weeks after planting.
Why are my potatoes small?
Close spacing shares the root zone among more tubers. Minnesota says commercial seed tubers grow into more vigorous plants that may make fewer tubers but a higher total yield per plant. Early digging also gives small tubers, since Minnesota says mature tubers come after plants dry. For how stress shapes yields, see the effects of environmental stresses on weed plants.
How do spacing and water affect tuber size?
Minnesota says early dry spells can cause knobby or hollow potatoes and stop new tubers from forming. It suggests a thorough soak once or twice a week. Maryland says to water plants well when rain is lacking, mostly while tubers develop. It ties misshapen tubers to too much or too little water. Maryland says a thick straw mulch after hilling holds soil cool and moist. Learn signs of dry roots in underwatering cannabis and mulch options in mulch for cannabis.
When should you dig potatoes for full size?
| Goal | Spacing or timing | Source |
|---|---|---|
| New potatoes | 9 inches apart | Maryland Extension |
| Storage potatoes | Up to 20 inches apart | Maryland Extension |
| New potato harvest | 7 to 8 weeks after planting | Minnesota Extension |
| Mature harvest | After vines dry | Minnesota Extension |
| Seed piece weight | 1 3/4 to 2 1/4 ounces | Maine Extension |
How to: step by step
- Buy certified seed tubers.
- Cut blocky seed pieces near 2 ounces with one eye or more.
- Space plants 12 to 20 inches apart for larger tubers.
- Hill soil as shoots grow and mulch with straw.
- Water deeply once or twice a week.
- Dig after the vines have dried.
Troubleshooting
Many tiny tubers: widen spacing next season.
Knobby or hollow tubers: water more evenly early on.
Poorly shaped tubers in heavy soil: Maine says poorly drained soil gives poorly shaped potatoes. See soil compaction in cannabis beds.
Give each plant room
Wider spacing, steady water and patience at harvest give larger potatoes. Kind Seed Co shares more notes for growers who raise vegetables next to cannabis.
Sources
- Growing potatoes in home gardens, University of Minnesota Extension
- Potatoes, University of Maryland Extension
- Potato facts: growing potatoes in the home garden (Bulletin 2077), University of Maine Cooperative Extension
FAQ
How far apart should potatoes be planted?
Maryland Extension says 9 inches for new potatoes and up to 20 inches for large storage potatoes.
When do potatoes form tubers?
Maryland says to side dress about 6 weeks after planting when tubers begin to form.
Can small potatoes be eaten?
Yes. Minnesota says you can dig new potatoes about seven to eight weeks after planting.
Does seed piece size matter?
Maine Extension says pieces should be blocky with at least one eye and weigh 1 3/4 to 2 1/4 ounces. It advises against seed smaller than one inch.
Can I plant grocery store potatoes?
Minnesota and Maine advise against it. Minnesota says store potatoes may be slow to grow.
