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Originally published March 7, 2014 at 8:00 AM | Page modified March 7, 2014 at 10:06 AM

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Q&A: Hypericum rust, and all about yacón

Garden writer Ciscoe Morris answers reader questions on Hypericum rust, which causes brown spots on the leaves of St. John’s wort, and yacón, which forms delicious edible underground tubers.

Special to The Seattle Times

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Ciscoe’s Picks

“Bugs — Eek, Squish, Splat!”: Ciscoe Morris shares his environmentally friendly methods to get rid of bad bugs and help good bugs thrive, part of the Snohomish County Master Gardener Foundation Sustainable Gardening Winter Speaker Series. 9:30-11:30 a.m. Friday, March 14, Mukilteo Presbyterian Church social hall, 4514 84th St. S.W., Mukilteo; series tickets sold in advance, but $20 individual tickets available at the door on a first-come basis (425-357-6010 or

Seattle Tilth’s March Edible Plant Sale: 9 a.m.-3 p.m. Saturday, March 15; “Early Bird” sale from 6-7:30 p.m. Friday, March 14, for $25. Pacific Market Center Parking Garage, 6100 Fourth Ave. S. (enter on Fifth Avenue South), Seattle (

“Talk, Walk & Weed” with Dan Hinkley at Heronswood: 10 a.m.-2 p.m. Saturday, March 15. Learn about the restoration work at Heronswood, walk through the gardens with co-founder Hinkley and volunteer some time weeding. Bring your own brown-bag lunch, warm clothes, gloves and hand tools for weeding. Heronswood, 7530 N.E. 288th St., Kingston, Kitsap County (

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In the Garden

Q: The bank in front of our house has always been covered in St. John’s wort. Loved it ... but suddenly a couple of years ago, it was overcome with rust. Is there a solution?

A: Hypericum rust moved into our area a number of years ago. It causes brown spots on the leaves and makes the entire plant look like it’s dying. It probably won’t kill, or even seriously weaken your St. John’s wort (Hypericum calycinum) but it will make it so ugly you’ll wish it would.

Chemical sprays, although sometimes effective, have to be applied right as new growth appears and repeat sprays are necessary until the rain stops, a totally unrealistic undertaking on an embankment.

The only cultural treatment recommended is to mow the plants down about the time growth starts in spring, and rake up and remove from the premises all infected leaves, equally unrealistic on a bank. I find that if you cut the plants near to the ground after they get infected in early summer, they grow back and remain disease free for the rest of summer as long as it doesn’t rain too much.

Unfortunately, once a plant is infected, Hypericum rust is tenacious and will be back to haunt you every spring, forcing you to live with it, or deal with it in a losing battle on a yearly basis. The good news is that this rust is specific only to Hypericum, so you don’t have to worry that a replacement plant will be infected.

Q: A Master Gardener friend of mine told me about the health benefits of yacón. Is it easy to grow?

A: Yacón (Smallanthus sonchifolius) is a perennial food crop that has been grown and eaten by peoples of the Andes Mountains for centuries.

A close relative of sunflower and Jerusalem artichoke, yacón forms delicious edible underground tubers that are juicy, sweet and crispy. It can be eaten cooked or raw and is a delectable addition in salads. Yacón is high in fiber yet low in calories, and also contains ingredients that enhance colon health and digestion. In addition, the sugars in yacón are not harmful to diabetics.

You need room if you’re going to grow yacón in your vegetable garden. The fast-growing plant has foliage that resembles a sunflower and can reach 6 feet tall.

Around Mother’s Day, plant the tubers 2-inches deep in rich, well-drained soil in full sun. Work in a half-cup of organic-tomato food before planting, and water as necessary to keep the soil evenly moist during the entire season. Other than that, be patient. In the Pacific Northwest, it can take 5 to 7 months to produce a crop.

Wait to harvest until cold weather turns the top growth black, as the tubers develop sweeter flavor after the plant experiences a bit of frigid weather. To harvest, lift the entire clump. The root system is made up of small round purple tubers near the surface, followed by long orange and smaller reddish tubers further down in the root mass.

Snap or cut off the edible orange and red tubers, and dry them in the sun or in a protected location. The edible tubers will store for two to three months layered in a cardboard box filled with sand or peat moss if kept at about 40 degrees. Peel both the outer and inner layers of skin before serving. Store the remaining purple tubers as you would dahlia bulbs for replanting next spring.

Ciscoe Morris: “Gardening With Ciscoe” airs at 10 a.m. Saturdays on KING 5.

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