Sweet Potato in Zone 9a & 9b

Ipomoea batatas

When to plant sweet potato in zone 9b

Zones 9a and 9b share the same average frost dates in our data, so this page covers both.

Method: Start indoors: Start indoors from seed, then transplant outside. Sweet Potato needs a head start most zones can't give it by direct-sowing alone.

Start indoors	Dec 21–Dec 28
Direct sow / transplant outside	Mar 8–Mar 15
Estimated harvest	Jun 26–Jul 3 (~110 days after transplanting)

Spacing: about 4 square feet per plant (square-foot-gardening spacing). Mature height: 0.5-1 ft.

Sweet potato isn't related to the regular potato at all. It's grown from slips, which are rooted sprouts started from a mature sweet potato, rather than from seed or a cut tuber. It also wants more heat and a longer season than most gardeners expect, which is why an early indoor start matters even though the plant itself is a vigorous, sprawling vine once it's established.

How sweet potato fits zone 9's season

Zone 9b's frost-free window runs about 293 days, from February 15 to December 5. Sweet Potato needs about 110 days from transplant to first harvest.

Good companions

Bush Beans: Beans fix nitrogen that heavy-feeding sweet potato vines use.

Where to buy sweet potato seeds

See why we recommend these suppliers →

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