PLACERVILLE, CALIFORNIA

Prospecting

Grow for it: Aggressive garden plants

By April 25, 2011

KIT SMITH

KIT SMITH

Sometimes the home gardener selects an attractive plant for the landscape only to find out later that it is aggressive, and, if left untended, takes over more of the planting area than was intended.

These plants do not fall within the definition of weeds, because they are wanted in the garden but, like weeds, they can get easily get out of control to compete with other plants for water, nutrients and space. Additionally, they are not on any invasive plant list because even though they have a competitive advantage, these plants can be kept in check with some physical and mechanical help by the home gardener.

The following are desirable plants but must be managed to keep them within their designated space.

Hedera helix, English ivy, is invasive. If you plant English ivy or one of its varieties, take care to control it. Ivy spreads by aerial rootlets. Trim ivy two to three times a year to ensure that its growth does not smother smaller or more fragile plants or vine up tree trunks.

Lonicera, honeysuckle, is a vine. Thin honeysuckle every year after bloom and before spring growth by cutting it to the ground. Lonicera japonica ‘halliana’ is the most vigorous and can smother weaker plants.

The branches of the Rosmarinus officinalis, rosemary, root wherever they touch the ground. The creeping and spreading varieties will spread indefinitely. Prune branches to the desired shape and size. Frequently pinch the tips when the plant is small.

Stachys byzantine, lamb’s ears, spreads easily by surface runners. Control this plant by removing stray plants.

Oenothera speciosa, Mexican evening primrose, which, despite its name, blooms pink flowers during the day. It is a perennial that spreads by rhizomes and forms rosettes of leaves. Pull out the rosettes so that this Primrose does not overrun the space.

Bamboo propagates by runners that grow rapidly at various distances from the parent and then send up vertical shoots. Mature bamboo shoots grow very fast in their brief growth period. Bamboo also propagates by rhizomes that are shallow underground and spread sideways. Contain bamboo with a barrier that is three feet deep in the ground and has a two inch thick lip above ground. Or surround the plant with a sand-filled trench one foot wide by one foot deep to make it easy to sever spreading rhizomes.

Campsis, trumpet vine, is a beautiful flowering summer plant that spreads by suckering roots and five-inch long seedpods. Pull up the spreading volunteers and remove the pods and dispose of them, but not in the compost pile. To control the main plant after bloom in the fall, cut some branches back to the ground and thin others. During summer, pinch back the shoot tips to keep the plant bushy.

Beware if you hear the words ‘vigorous’ or ‘fast growing’ used to describe a plant.  Think about whether a plant with this description is one you want in the place and space you intend to plant.

Saturday, April 30, UCCE/Master Gardeners will be presenting “Landscape Irrigation.” The class starts at 9 a.m. and will be held in the Veterans Memorial Building at 130 Placerville Drive in Placerville.

The Master Gardeners are available to answer home gardening questions Tuesday through Friday, 9 a.m. to noon, by calling 530-621-5512.  The office is located at 311 Fair Lane in Placerville. Walk-ins are welcome.

For more information about public education classes and activities, go to the Master Gardener Website at ceeldorado.ucdavis.edu/Master_Gardener/.

 

Kit Smith

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