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Tuesday - March 20, 2012

From: Pflugerville, TX
Region: Southwest
Topic: Invasive Plants, Propagation, Problem Plants, Vines
Title: Controlling Passionflora Incarnata propagation
Answered by: Brigid & Larry Larson

QUESTION:

Would a cinderblock raised bed, 8 inches in height, be sufficient to contain the roots of passiflora incarnata and keep them from traveling to places where I don't want the vine? Are the roots deeper than 8 inches?

ANSWER:

No, not quite deep enough. Mr Smarty Plants had quite a search to try and get some real data on Passiflora incarnata (Purple passionflower) and its root system!

Its real clear from the regular stuff one finds on the web that it propagates via roots and a couple similar techniques. This article from TAMU notes air-layering and root propagation. They considered that mowing was sufficient to keep the vine under control. On the other hand, this comment from a garden forum claimed really long distances.

But - Mr Smarty Plants hit the gold mine with a proper scientific paper on the subject!

Weed Science. 1985. Volume 33:484-490 "Reproductive Biology and Herbicidal Sensitivity of Maypop Passionflower (Passiflora incarnata)" by WEHTJE, REED, and DUTE.

Two bits of information caught my eye. They noted: "Sections taken from the horizontal axes were within 30 cm of the soil surface, which constitute the primary means of reinfestation." [30cm is quite close to a foot] and the first figure in the paper was of the "Root system of maypop passionflower at the end of one year's growth from a seedling." This figure showed new growth emerging from the ~30cm area measured from the surface and 170cm [5 1/2 feet!] as it's longest extent [in depth].

To my mind, you can probably reduce your control efforts quite a bit with a raised bed, but not totally. If you are willing to do a little bit of controling and/or mowing outside your raised beds then you probably can keep it where you want it!

From the Image Gallery

Maypop
Passiflora incarnata