Gardening Column

Chip Bubl works at the Oregon State University Extension Service – Columbia County, 505 N. Columbia River Highway in St. Helens. He may be reached at 503 397-3462, email,

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Garden tidbits for March

Lawns need attention this month with moss removal, mowing when necessary and possible, and lawn fertilizing. Soils are generally too wet to aerate in March (the aerating tool seals the hole if the soil is too wet) but is possible if we have a lot of dry weather.

If you fertilize your lawn this month, consider adding lime at the rate of 60-75 pounds per 1000 square feet about two weeks after you fertilize if you haven’t done that in a while.

Several nice days ago, European gray slugs paraded across our road and driveway. Slug management is starting early this year. Put out baits where you know slug susceptible plants are growing even if the plants haven’t emerged yet. I feel most comfortable with iron phosphate based baits since they have a good safety profile for dogs (Sluggo is one trade name). This is the teachable moment for slugs.

Peas (both edible and floral) can be planted now. They will grow much faster if you cover them with row cover cloches to improve soil and air temperatures around them.

Cardboard for weed control

For those of you who don’t wish to use chemicals on your garden for late spring weed control, you can use cardboard. Place a single layer of cardboard (or several thicknesses of newspaper) over the garden area and cover the sheets with compost or other organic matter. Wait several months, and till it all into the garden.

The rain will make the cardboard easy to till and the shading will eliminate a good portion of the quackgrass, chickweed, and other winter weeds. Some gardeners transplant starts right through un-tilled cardboard. However, you should make some holes in it with rebar to allow irrigation water to reach roots.

The cardboard needs to go on right away to have the desired results. You can also tarp areas (without cardboard) right now and get decent weed control if you don’t plant to plant until May.

Cardboard (or newspaper) and organic mulch can also be used on the garden paths in the summer.

A new-ish paper wasp

As plant an insect species travel with ease from continent to continent, it is no surprise that Columbia County has a new-ish wasp. This European import is paper wasp (Polistes dominulus) that looks much like a small yellow jacket. One distinguishing physical feature is a bright yellow to orange antenna. As a paper wasp, it creates single paper combs that are not enclosed (unlike the yellow jacket which encloses its nest).

Also unlike a yellow jacket, the female P. dominulus will reuse last year’s nest combs, unheard of in the yellow jacket world. Even more unusual, several females will cooperatively rear and tend eggs in a single nest. These nests, each individual, can be clustered together in great numbers.

Paper wasp colonies die out in the late fall (as do yellow jackets). Pregnant queens who left the nest hunker down for the winter. While yellow jacket queens hunker in solitude, this paper wasp is a bit gregarious and it is not uncommon to have a number of them hunkering together, often in attics or other human constructed structures.

People who have bird boxes have noticed that the over-wintering cluster like those spaces and may discourage birds who nest early from occupying the boxes.

They do sting, repeatedly and painfully, just like a yellow jacket. They may not be as aggressive as ground-nesting yellow jackets but should be treated with respect.

There is a silver lining. They get going early in the spring. In fact, during warm spells, like we had last week, some females from an over-wintering cluster will go out and get insects for the rest to feed on. Nest building starts early as well, often in human constructed spaces. This early activity provides useful insect predation at a time when other predatory insects are just warming up.

Clearly there are areas where paper nests are inappropriate. Those nests are best removed in the early-mid spring before the first brood hatches. But if you can live with their choice of nesting space, they will provide you a lot of caterpillar, aphid and other insect control.

Anna’s hummingbirds “chirp” with their tails

Anna’s hummingbirds are common residents of Columbia County. Males make acrobatic climbs and then swoop down over the females to impress them. As they descend at speeds of 50 mph, they open their tail feathers and emit a loud, sharp chirp. Scientists found that this had nothing to do with vocal chords. Instead, the structure of the edge of the outermost feathers produced the sound as the air rushed over them, causing them to vibrate like a reed on a clarinet.

The OSU Extension office is closed to face-to-face public contact but you can still reach us!

Last week, Oregon State University closed all Extension offices to face-to-face contact starting this past Monday. This is part of the larger Oregon State University effort to slow the spread of COVID-19. The University itself is teaching completely digitally for the rest of the academic year. Our volunteers are also restricted in what they can do relative to the program(s) of OSU Extension they are connected to. Most of them have been already contacted.

However, all of us (faculty and staff) will still be working (most of the time in the office), answering phone calls, email messages, writing newspaper columns and newsletters, and working to develop programs that can reach you on-line.

We are really committed to helping our communities in any way we can, especially in our areas of subject matter expertise (farming, gardening, forestry, food, food safety, and nutrition, healthy decision-making, and youth education) and any other way we can enrich your life and/or make you safer in these challenging times. Please do not hesitate to contact us! And please, take all steps necessary to ensure that you and your loved ones are safe.

OSU Master Gardener™ Spring Fair/Tomato Sale is cancelled for 2020

This was another difficult decision. At present, there is an indefinite ban statewide on all events that draw 250 people or more. In consultation with our OSU Regional Director and the Program Leader for Community Horticulture (which includes the MG program) we made the decision to cancel the event on the odds that ban would still be in place by the Spring Fair date was significant and the risk to the public was likely to still be high. I know many of you will be disappointed. But we promise to come roaring back next year with the best Spring Fair ever!

Scappoose Bay Watershed Council’s Native Plant Sale Saturday, April 11--POSTPONED

Join the Watershed Council at their Spring Native Plant Sale Saturday, April 11th, from 9 am to 3 pm. This is their semi-annual event to get you ready for spring and summer planting. They have lots of new plants at great prices – all native to our area. Staff and volunteers are available to help chose plants suggest gardening ideas, and provide information on establishing and maintaining native vegetation. For more information see

The Plant Sale is from 9am to 3pm at the SBWC nursery, located behind Scappoose High School. Look for signs – go east on SE High School Way and turn into the parking lot between the high school and the school ball field areas.

Free newsletter (what a deal!)

The Oregon State University Extension office in Columbia County publishes a monthly newsletter on gardening and farming topics (called County Living) written/edited by yours truly. All you need to do is ask for it and it will be mailed or emailed to you. Call 503 397-3462 to be put on the list. Alternatively, you can find it on the web at

Many Extension publications available online

Are you putting up salsa, saving seeds, or thinking about planting grapes? OSU has a large number of its publications available for free download. Just go to . Click on publications and start exploring.

The Extension Service offers its programs and materials equally to all people.

Chip Bubl works at the Oregon State University Extension Service – Columbia County, 505 N. Columbia River Highway in St. Helens. He may be reached at 503 397-3462, email,


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