Ask an expert? These are the top 10 questions for Oregon gardeners in 2021



In 2021, Oregon gardeners sought answers to a myriad of questions for experts at the Oregon State University Extension Service, but a few topics dominated. We’re talking about mulch of all kinds, raised beds, and how and when to prune. But the question that attracted the most readers took us by surprise.

And remember. If you have a question about gardening in Oregon, you can turn to Ask an Expert, an online question-and-answer tool from the Oregon State University Extension Service. Teachers and master gardeners usually respond within two working days, usually less. To ask a question, visit the OSU extension website, enter your question and indicate the county where you live.

These are the 10 most read Ask an Expert articles on OregonLive in 2021.

10. The early pruning of roses could cause dieback, leading to re-pruning next spring. (January 16)

Q: With this hot weather in early January, my roses are growing like crazy and having multiple flowers. How to protect roses if the weather turns cold again in February? – Multnomah County

A: In western Oregon / Willamette Valley, the best time to prune is from mid-February to early March. Pruning mid-month or later is recommended. This time is suggested because generally we will have a time that encourages the plant to start growing. Pruning earlier (before the last frost or expected bad weather) will cause problems for the rose bush. See the full answer from Jack Master, OSU Extension Master Gardener Diagnostician, here.

Are coffee grounds good for the garden or not?Rosemarie Stein / staff

9. When it comes to coffee grounds in the compost, how much is too much? (November 6)

Q: I was wondering if we could have too much coffee grounds in a compost heap?

I have a three-bin system and take so many leaves from my neighbor’s garden each fall (about 30 yard bags). This year, to make sure I have a better balance, I get a 5 gallon bucket of coffee grounds from a local coffee shop every week and add it to each bin in turn so that every three weeks , each section will get the patterns in addition to my kitchen scraps.

I was wondering if the overall pH of my compost would be relatively balanced if I mixed the soil with this huge bounty of leaves or should I go back to the soil? – Multnomah County

A: It’s interesting that when a compost pile is made up mostly of plant matter (leaves, food scraps, coffee grounds) it starts out at a low pH and reaches around neutral. Low pH because the decomposition of plant matter results in the release of organic acids – initially. Find out how Linda Brewer, OSU Extension Floor Specialist, explains how to get the right balance here.


Hydrangeas in full bloom.

8. Is it too late to prune a hydrangea? (November 27)

Q: Is it too late to prune my hydrangea? Can I see new buds on the stems so I can leave them for next year’s growth if needed, or do I just have to suck them up and prune them next season? – Clackamas County

A: It turns out that now is the time to trim, although it can be difficult to trim while holding an umbrella! I am attaching a item on hydrangeas; go to the “Pruning” section and you will get some great tips. – Rhonda Frick-Wright, OSU Extension Master Gardener (You can find more advice on pruning, this time perennials, here)

7. Is my HOA’s application of bark dust every year a waste of money? (November 14)

Q: I live in an HOA in Corvallis. Every year or two we pay dearly to have bark dust blown into the beds around the bushes. It is blown to save the expense of humans to shovel it. Is there a study of the relative costs of blowing bark dust every two years versus having larger pieces of bark shoveled by humans? In addition, would it be more profitable in some less obvious places to remove vegetation and cover the area with “stone path” (rock on the ground designed not to move over time)? Presumably all that would be needed after this would be an infrequent application of herbicide. – Benton County

A: I can’t answer your question about the relative cost of different mulch applications – you will need to get quotes from landscaping contractors. Our goal in the Extension Master Gardener program is to educate people about sustainable gardening methods, so what I can do is discuss the pros and cons of the materials you suggest and how they relate to the health of the garden. ground. If there are plants growing in these spaces, then good soil health is essential for their longevity and growth. See the full answer from Signe Danler, OSU Extension Master Gardener instructor, here.

With a labeled sign "compost," black organic matter is piled up next to a wheelbarrow full of stuff.

The best soil amendment is partially decomposed organic matter, better known as compost.OSU Extension Service

6. Compost, mulch or bark: what better for a flower garden? (October 26)

Q: What is better, mulch versus compost versus bark for our existing healthy landscaped flower garden? When / why / how to use all or part of it? We applied high quality compost a year and a half ago when we started the flower garden. Nothing added since. – Washington County

A: Thank you for your question on the different mulches (these are all technically mulches) you can put on your flower bed. They all have advantages and disadvantages. See OSU Extension’s Master Gardener Rhonda Frick-Wight’s full answer here.

5. When wood chips are added to the soil, they compete with plants for nutrients. (May 29)

Q: We added about 3-4 inches of yard debris compost to our yard. We got it from a landscaping company as a soil amendment. The leaves of our cucumbers, beans, tomatoes and squash are all starting to turn yellow. Cucumbers have the worst. I don’t know if it’s compost or what. I did not do a soil test. No advice? Can I plow topsoil? – Clackamas County

A: Yes, you have solved the “compost” problem. As you can see from the size of the pieces of wood, what they call compost hasn’t really broken down yet. What he’s doing right now is trying to decompose using nitrogen in competition with your plants. Obviously, the “compost” is a winner. See how OSU Extension Master Gardener Rhonda Frick-Wright explains in detail here.

A row of empty garden beds are displayed

Fall is a good time to test the soil in raised beds.Advance on State Island

4. Should raised beds be covered for the winter? (October 16)

Q: Our garden is three raised flower beds and the rest of the garden we usually put green beans, zucchini, yellow squash, and a winter squash in the ground. We try to rotate the crops from year to year. I would like to ask if we should enrich the soil with something now. … I also wonder if we should get something to cover the raised beds for the winter? – Lane County

A: Having some kind of cover for the garden in the winter is a great idea. It helps prevent soil compaction by rain. A cover crop is ideal because it catches all soluble nutrients and protects the surface and reduces weeds. Pat Patterson, a retired OSU Extension horticulturalist, also has suggestions for a soil pH test. See Patterson’s full answer here.

3. Can I reuse the soil? (Oct 28)

Q: Is it better to store the used potting soil for reuse in a sealed plastic container in winter? It has been used in outdoor pots, flowers and vegetables. – Clackamas County

A: Yes, you can put it in a sealed plastic jar and store in a dry place. You can also use burlap bags or heavy cardboard boxes. Keep the soil in a dry place and make sure the soil is dry. Moisture can cause mold to grow. It can also be stored in the jar in which it was used. But there is more you should know. See the full answer from Sheryl Casteen, Master Gardener at OSU Extension, here.

2. Follow these steps to replenish the nutrients in the raised beds. (March 13)

Q: We have two raised beds in our garden and I was looking for some advice on how best to prepare the ground for this year’s garden. Both planters are approximately 8 feet by 2 feet long by 2 feet wide and 2.5 feet deep. One was built two summers ago and the other was built last summer. Both beds were filled with compost when they were built.

Last year we added some compost to the original garden box and mixed it with the soil that was already there. Other than that, we didn’t add anything else to the ground. Is there anything we should add to these planters to replace the nutrients that plants have used for the past two years before we planted them this year?

In a garden box, we grew potatoes, peppers, basil, carrots and garlic. The more recent of the two had tomato plants, green onions and carrots, although the tomato plants took over so the other vegetables did not survive. – Marion County

A: Vegetables usually do well for about a year in a new bed, but because they are annuals, they quickly deplete nutrients, which need to be replenished regularly. See the rest of the response from Lynn Marie Sullivan, OSU Extension Master Gardener, here.

Clover covers a lawn in front of a house

This clover lawn was too beautiful to be mowed. OSU Extension Service

1. This clover lawn has been allowed to grow up to 8 inches. Now what? (Posted on October 3)

Q: In the summer of 2020, we removed our lawn and replaced it with mini clover. It filled up really well and we kept it mowed down to about 2-3 inches.

However, this spring it looked so beautiful we couldn’t bear to mow it, so we let it grow unhindered all summer. He’s grown to around 8 inches, and we like him that way.

One wonders whether it should be mowed in the fall after the leaves have finished falling, in order to let it grow again in the spring. We want to make sure he’s still big next year. What to do to help him get through the winter? – Marion County

A: OSU did research on eco-lawns, but these studies were conducted on regular mowing schedules that kept lawns at a height of about 3 inches. We therefore do not have data on the best way to manage this specific situation of an adult eco-lawn.

That said, OSU Extension horticulturalist Brooke Edmunds had a few ideas. See them here.

– The Oregonian / OregonLive shares weekly questions and answers from the OSU Extension Service’s Ask an Expert tool at



Comments are closed.