Growing Mashua: A Complete Profile
By Growing Home Greens Team · August 10, 2026
Mashua is a vigorous climbing Andean tuber crop and, botanically, a relative of the ornamental nasturtium, though it’s grown for its tubers rather than its flowers.
It wants a trellis
Give mashua something to climb and yields can reach up to four times what an unsupported, sprawling plant produces, up to about 20 pounds per plant on a trellis versus closer to 5 pounds on the ground. It’s a vigorous vine, so plan for real vertical space, not a token stake.
A short-day crop, like oca
Most mashua varieties won’t start forming tubers until after the fall equinox, around September 21, and aren’t ready for harvest until mid-November, the same short-day pattern as oca. That makes a long, frost-free fall essential in most climates. The variety ‘Ken Aslet’ is a real exception: it begins forming tubers earlier and can produce a reasonably good yield by mid-October, useful where an early frost would otherwise cut the season short.
Cool summers preferred
Mashua does best where summer highs stay under 80°F, and it’s easiest to grow in the maritime Pacific Northwest. Elsewhere, afternoon shade helps it cope with hotter summers. It’s hardy only to about USDA zone 9a, so in most of the country it’s dug and replanted annually.
Mashua has no well-established companion pairings, and nothing it needs to be kept away from. In the Garden Designer, give it a trellis and plenty of vertical room rather than treating it as a low-growing root crop.
Source: Mashua (Tropaeolum tuberosum), Cultivariable.
Companion planting guide for Mashua · Find your planting dates
Typically viable in USDA zones 6-9. Not sure your zone? Look it up by ZIP code.
Mature height: 2-8 ft
Method: Direct sow: Direct-sow outside. It doesn't transplant well, or doesn't need the extra time indoors.
When to plant mashua, by zone
Every zone mashua grows in. Pick your zone in the header and it will be highlighted here. Each zone links to its full page.
| Zone | Start indoors | Sow or plant out | Harvest |
|---|---|---|---|
| 6a & 6b | Not usually | Apr 25–May 2 | Nov 21–Nov 28 |
| 7a & 7b | Not usually | Apr 10–Apr 17 | Nov 6–Nov 13 |
| 8a & 8b | Not usually | Mar 25–Apr 1 | Oct 21–Oct 28 |
| 9a & 9b | Not usually | Feb 15–Feb 22 | Sep 13–Sep 20 |
Harvest dates are about 210 days after the sow or plant-out date.
See exact start-indoors, direct-sow, and harvest dates for your zone →
How many Mashua plants fit per square foot?
Spacing: about 2 square feet per plant (square-foot-gardening spacing). Mature height: 2-8 ft.
Varieties worth considering
- 'Ken Aslet': Cultivariable singles this variety out as an exception to mashua's usual short-day tuber timing: it forms tubers earlier and can produce a reasonably good yield by mid-October instead of mid-November. (source)
Why each variety is listed comes from the source shown next to it. We haven't grown these ourselves yet, so treat this as a research-backed starting point, not a personal endorsement. The buy links are separate from those sources: they go to seed suppliers that sell that exact variety, and we may earn a commission on some of them.
Where to buy mashua seeds
None of the seed suppliers we list carries mashua seeds right now. A local garden center or a specialty seed house is the place to look.
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See it growing
Search YouTube for "growing mashua" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
Pin this for later
Growing Mashua: A vigorous climbing relative of the ornamental nasturtium, grown instead for its tubers, which yield far better trellised than left to sprawl on the ground.
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