Jerusalem Artichoke

Plant sunchoke tubers once the soil warms

Plant tubers about 6 inches deep and 2 to 3 feet apart once soil temperature reaches 6-7 C (mid 40s F). Whole tubers are the safest choice; if you cut them, do not let the pieces dry out before they go in the ground. Sunchokes need roughly 125 days of growth plus a cool autumn to bulk up tubers, so they want to be in the ground early, but a tuber pushed into cold wet soil rots before it ever sprouts.

⚠ Sunchoke spreads by rhizome and any fragment left behind sprouts the following spring, so choose a spot you are willing to keep in sunchokes for years, or plant into a container or lined barrel.

Keep sunchokes evenly watered through summer

Water consistently across the summer, and deeply about once a week for plants in containers. Mulch to hold moisture, and keep them out of ground that puddles. Tubers are built late in the season out of everything the plant photosynthesizes all summer, so a drought-checked plant sets small knobby tubers - while standing water rots them instead.

Feed for yield, or skip it on rich ground

On average or light soil, apply a balanced NPK fertilizer such as 20-20-20 monthly through the growing season, and watch for yellowing or stunting as a cue you are short. On rich garden soil, sunchokes crop well with nothing at all. Ohio State reports higher tuber yields from regular balanced feeding, while UC extension finds no fertilizer necessary - the difference is your soil, not the plant, so let the soil decide.

Scout for white mold at the base of the stems

Check stem bases and lower leaves for wilting that runs from the top down and hooks the growing tip into a shepherd's crook, for dense white cottony mycelium at the soil line and on roots, and for hard black bb-sized sclerotia with white interiors. Pull infected plants whole and get them off the site - do not compost them. Sclerotinia sclerotiorum is the major disease of sunchoke, and its sclerotia survive for years in soil and ride along on tubers into storage. There is little varietal resistance to fall back on, so finding it early is most of the control.

⚠ Few pesticides are labeled for Jerusalem artichoke. The biological control Coniothyrium minitans is the option with support behind it, and it works only alongside weeding, canopy reduction, and volunteer removal - not instead of them.

Clear volunteers, and rest the ground if white mold showed up

Once you have finished digging, work back through the bed and lift every tuber fragment you can find, then pull volunteers as they sprout the next spring. If white mold appeared during the season, rotate that ground into a grass-family crop such as maize for at least three years before you plant sunchokes there again. Sclerotia persist in the soil for years and the fungus attacks a huge range of broadleaf hosts, so only a long rotation into a non-host starves it out. Volunteer sunchokes keep the host alive through the rotation and quietly undo it.

Dig sunchokes after the first hard frost

Wait until frost has knocked the tops down and the plant dies back, cut the stems back to roughly 8 inches so you can find the crowns, then dig only as many as you need at a time. Leave the rest in the ground and keep digging through winter into March. Frost is what makes this crop worth eating - cold shifts the stored inulin and the tubers sweeten. Dug tubers have paper-thin skins and shrivel within about three weeks in the fridge, so undug ground is the best root cellar you have.