Grab a hoe and free the garden of liverwort

June 18, 2008 

Ah, there are so many things to address this time of year and so little space in which to do it. Let's start with those colonies of green cornflakes and lichenlike, crusty bran coverings invading gardens. These are liverworts, primitive plants that are relatives of mosses. They grow in poorly drained soils and exposed soils near poorly drained ones.

What readers are complaining about are the plant's thallus. On the bottom of these cornflake-shaped, leathery pads are rhizoids that attach to the soil. If you look carefully, you may see a small flower on a stem growing out of the green thallus. This is the male or female gametophyte, depending on which of the more than 300 kinds of liverworts has invaded your yard. These are fascinating and, to some, collectable plants.

Ah, but you want to know is how to get rid of them as they are creepy looking and seem to smother out anything from growing in the soil. Use a hoe, winged-weed or similar tool to slice off the thalluses. Then toss down a bit of compost or humus and a few inches of mulch. If you are a regular reader of this column or if you team with microbes, you should realize that there are no bare soils in nature. Mulch.

Sometimes liverworts even get established in the lawn. Use a thatching rake to get the thallus up and then aerate the lawn or perforate it with a pitch fork. The idea is to improve drainage. Then apply compost if possible or a compost tea. It is the microbiology that starts the permanent drainage creation process.

How about those flowers on your rhubarb plants? I know you have them because I gave up my boycott of the vegetable I ate every single day of my childhood and bought Jude three plants. Pick off these flowers as soon as you see them forming. Start harvesting the stalks if you haven't already. There are red- and green-stalked varieties. On either one, the leaves are poisonous and should not be eaten.

This has been a terrific year for those mounds of yellow trollius, specifically, Trollius europaeus (as opposed to the taller, orange and mid-summer blooming variety, Trollius cultorum), in bloom all over Southcentral. You've seen them -- buttercup-yellow, quarter-sized flowers with a dozen or more forming a neat mound about 18 inches round. Here is a plant that belongs in every yard because in addition to its clumping nature, the leaves have a textured edge that makes the mounds of these plants worth having even without flowers. They always flower, no matter what the weather and trollius hold their petals a long time. Right now, they are in their prime.

This is a good time to divide clumps. Use a spade and simply slice clumps in half, leaving one half in the ground and removing the other. This half clump can be further divided if you wish, realizing it will take a few years for small clumps to get to the size where they generate the kind of interest of the original.

Next, do you have a cotoneaster bush or hedge? Then you most probably have cotoneaster webworms. These are also known as cotoneaster leaf rollers. They start out as tiny pale yellow caterpillars (with a dark green head) only about a 16th of an inch long. In just a couple of weeks they grow to 1/2-inch long, and they do so by eating the cotoneaster's leaves until they get enough food. Then, to add insult to injury, they curl up one last leaf and form a cocoon.

The solution to cotoneaster leaf rollers is Bacterium thuringenisis, aka Bt. Spray all the leaves so that as they eat caterpillars ingest the bacterium which will stop digestion. It takes about two or three days. Do not delay this chore.


Jeff Lowenfels is a member of the Garden Writers Hall of Fame. You can reach him at gardenerjeff.googlepages.com or by joining the "Garden Party" radio show from 10 a.m. to noon Saturdays on KBYR 700 AM.


Gardening calendar

• ALASKA BOTANICAL GARDEN FAIR AND ART SHOW: It is a must-attend event for the entire family. Fun for all and some great speakers. Hours are 11 a.m.- 6 p.m. Saturday and 11 a.m.- 5 p.m. Sunday. Food, plants, garden knickknacks. Speakers all day, including bulb expert Brent Heath of Brent and Becky's bulbs. He will be speaking at 12:30 p.m. both days. I will be speaking at 1:30 Saturday. For more information go to www.alaskabg.org.

• DANDELIONS: Keep at 'em.

• INVASIVE WEED WEEK: Pull those butter and egg plants before they flower.

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