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Getting purple loosestrife for your project

June 17, 2011

After receiving permission from the West Virginia Department of Agriculture, we were able to go dig up purple loosestrife root crowns. Purple loosestrife is a perennial plant that grows from a baseball-sized root mass every year. These root crowns can be dug up and repotted to grow plants for your Galerucella rearing projects. We dug up the crowns from lands where we already had agreements in place, so as to not trespass or remove property from a place where we did not have permission to do so. The digging was easiest with a round shovel with a pointed tip; a narrower shovel or one without a pointed tip would make the crowns harder to slice apart or lever out of the mud we found them in.

A potted root crown, with the stalks from last year’s growth visible.

To pot purple loosestrife root crowns, you will need a sufficient number of 3 or 5 gallon pots, a sufficient amount of soil (we used around 3 cubic yards for 24 pots), kiddie pools (each of ours could hold 12 pots), a shovel, plastic bags, and gloves (optional).
The root crowns were sliced out of the muddy soil using a pointed-tip shovel, then levered out onto the ground. The crowns were separated to get individual plants, then the previous year’s woody growth was removed with shears. The crowns were bagged in plastic and then put in pots for transport in a closed vehicle. It is important to only remove material from the crowns at the location you dig them up; if you remove the woody stalks or mud elsewhere, you run the risk of creating a new infestation by spreading seeds. Leave any material removed from the crowns at the site you dig them up.

Growing loosestrife.

The crowns were potted in 3 gallon pots in a potting soil with fertilizer already mixed in. We dumped the soil into a kiddie pool, moistened it with water, and potted the crowns, covering them with sufficient soil. The pots were then stood up in the pools, and the pools filled 1/3 of the way with water. The crowns will not need to be watered from the top if the pools are kept filled with sufficient water. Poking holes around ½ way up the sides of your kiddie pools will prevent overflow of the water from rain events.

Loosestrife pots in their pool.

Loosestrife grows fairly quickly, even after the rough handling of digging up the root crowns and re-potting them. To get a bushier loosestrife plant, and so more food for your beetles, you can pinch the tops of the plants off once they reach 12 inches tall. This removes what is called the ‘apical meristem’, or the main upward-growing part of the plant (also the main flowering part of the plant, later in the growing season). This means the plant has lost its ‘apical dominance’, and so the side branches of the plant will start to grow so the plant can still flower.

Side branches growing after the apical meristem has been pinched off.

Loosestrife is fairly easy to grow, and as long as you have a sharp shovel, sturdy boots and permission, it is fairly easy to get out of the field.

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