This climbing, pea family vine hails from Asia, but there are species native to the US as well. It grows rampantly engulfing pergolas, arbors, fences, walls and cars. It's the wisteria vine.
Wisteria vines are impressive. I remember seeing a Chinese wisteria vine engulfing a telephone pole loaded with fragrant, purple flowers in Philadelphia one April. The smell was intoxicating!
While we mostly know of the Japanese and Chinese varieties of wisteria like the one I saw in Philly, the best species to grow in the North is the Kentucky wisteria or Wisteria macrostachya. It's the hardiest wisteria, able to withstand our tough winters and still bloom in spring. Plus, it's not as aggressive so easier to keep in bounds. Wendy and I are growing 'Blue Moon' and 'Aunt Dee'. They produce fragrant, purple flowers, but the vine stays a “tame” 15 to 20 vine tall.
Wisteria love the sun and well-drained, fertile soil. The key with growing this vine is having a strong structure for support. Our vines shade a large pergola over our deck. A sturdy arbor, fence or wall works well too. Just trellis the vines at least 6 inches away from siding or a wall.
The second key is pruning. If not pruned twice a year wisteria can get out of control and not flower well. Train first year vines up a pole or supports until it reaches the desired height then top it and let it spread into framework branches. Each summer allow one leader to grow from each framework branch and cut back any side shoots. In winter cut back these leaders by one-half. Cut back any side shoots from the previous summer back to 2 inches long. The framework branches will slowly spread over an area and the side shoots will turn into short flowering spurs.
And now for this week's tip, cut back overwintering geraniums growing in a sunny window so they don't get too leggy. This will create a stockier plant that will be in flower in April.
Next week on the Vermont Garden Journal, I'll be talking about ground nuts. Until then, I'll be seeing you in the garden.
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