Mahon Yam

Family: Convolvulaceae Root Vegetable

Warm, sunlit flesh—deep orange with a silky, custard-like tenderness—defines Mahon Yam, a 90-day Orange Sweet Potato prized for its rich sweetness and velvety texture.

The tubers develop with an inviting, smooth skin and a generously rounded form, delivering dependable performance from garden to harvest. Grow Mahon Yam for glowing color in roasted trays, spoonable mashes, and vibrant purées, or for bold, sweet notes in pies and preserves.

Light: Full SunMaturity: 90 DaysHabit: Vine

Planting schedules and alerts are optimized for Columbus (Zone 6b).

Crop Dates

Milestone	Date
Start Indoors	Direct Sow
Last Frost	Apr 25th
Transplant / Sow Outdoors	Jun 20th
Harvest Begins	Sep 18th
Harvest Ends	Oct 16th

Crop Details

Trait	Value
Days to Maturity	90
Sun Requirements	Full Sun
Growth Habit	Vine
Support Needed	None
Planting Depth	Normal
Germination Temp (°F)	80
Min Soil Temp (°F)	65
Min Night Temp (°F)	55
Harden Off (days)	10

Culinary Notes

Chef's Note

Mahon Yam hits a sweet spot between dessert and comfort-food tuber: the flesh steams into an almost custard texture instead of fibrous bite. Roast it hard for caramel edges, then mash or purée without fear—it stays smooth and luminous on the spoon.

Best Uses

hot, high-heat roasting where the edges caramelize and the center stays spoon-soft
silky mash that turns glossy with butter and a splash of dairy
vibrant purée for soups and thickened sauces
sweet pie/preserve filling where it sets with minimal extra thickening

Flavor Profile

deep orange sweetness velvety, custard-like tenderness gentle earthy warmth

Kitchen Pairings

butter maple syrup cinnamon lime (or lemon) juice vanilla marshmallow

Frequently Asked Questions

What pest or disease commonly affects Ipomoea batatas (mahonyam), and how do I treat it?

Watch for sweetpotato weevil damage and especially sweetpotato scurf (dark, rough patches on tuber skin), which both become more visible during harvest. To reduce weevil impact, rotate away from other morning-glory relatives and avoid replanting from infested tubers; remove and destroy any severely affected plants early. For scurf, keep soil fertility balanced (avoid excess nitrogen), cure harvested roots warm for 7–10 days, and store in dry, well-ventilated conditions to limit spread.

How often should I water mahonyam during the main growing phase?

During active vine growth, keep the bed consistently moist but not waterlogged—aim for about 1–2 inches of water per week depending on heat and rainfall, and water when the top 1 inch of soil feels dry. Once roots begin swelling (mid-season), prioritize deep watering to reach the root zone, then taper slightly in the final 2–3 weeks to reduce splitting and rot. Mulch helps stabilize moisture for Ipomoea batatas in full sun beds.

How can I tell when mahonyam is ready to harvest?

Harvest at roughly 90 days after planting (start checking around day 85), when the vines begin to yellow and the tubers fill out. To confirm, gently dig a small test hole near the row and feel for firm, well-formed roots with skin that resists easy scuffing. Avoid leaving roots in cold, wet soil—harvest promptly once they’re mature and cure them warm for 7–10 days before long-term storage.