Gardening season is underway, and you may have questions. To ask one, simply go to the OSU Extension website, type it in and include the county where you live. A photo is very helpful.

Q: I am currently removing landscaping plastic from my backyard. It appears the previous owners thought white stretchy plastic would be a good idea (probably 15 years ago), so they covered the soil with a, now super thin, layer of mulch which has accumulated a good 3-to 4 inches of clay over it, with a healthy smattering of 3/4 inch river rocks mixed in.

A month ago, when I started, the rocks make it impossible to use anything other than a hand spade to get through. To my delight, I’ve found that the dry weather has conveniently caused the clay to crack, so I’ve been able to pull plates of the stuff up to expose the mulch (and likely old topsoil) layer, which I’m able to gently remove with a hand spade to expose the plastic and peel back. I’ve made it down our 100-foot fence line over the last couple of weekends and am now doubling back perpendicularly, so that I can toss the soil where I’ve already been.

Now I’ve got a healthy pile of clay “chunks” that are starting to pile up, and the earth beneath the plastic is even more clay and rocks, I feel like I might be piling one problem onto another.

With that context, I’m wondering how to deal with the pile of clay chunks. Do I water them and then use a rototiller, or do I need to pull out my trusty pickaxe to break it down?

The soil underneath also concerns me. I’m sure it will crack too now that it’s exposed to the elements. Do I leave it and add good stuff on top? If I go this route, how deep of the good stuff (and what) should I be using?

The plastic removal project is a big one and will likely take me through October at the rate I’m going (that’s okay, the excuse to be outside is a welcome one after our rainy winter and spring). My goal however is by next spring I’d like to start landscaping the area.

Over the winter, what can I do to prepare the space? Do you have any other tips or rabbit holes I could dive into? – Linn County

A: Thirty-five years ago, I was in exactly your position, and I have lived to tell the tale. Well, I only had a space that was 80-by-6-feet, but still.  My biggest message to you is that we have clay soils in this part of the valley due to geologic actions taking place at the end of the last ice age – 10,000-18,000 years ago. Like diamonds, clay soils are forever.

I still live on that same Benton County property and have just learned to live with clay soils. They are not bad, not heavy, just high clay content.

Why not read up on hugelkultur or lasagna beds? This has been the key to my success. Please don’t think about tilling anything into the soil. The best you can do is spread it on top and let the tincture of time change the conditions below. MOST OF ALL don’t let anybody talk you into adding sand to the soil.

With those clay chunks you have choices. You could just stack them up and make them a part of your raised planting beds. And you could include some brought in soil as part of your beds. I realize that’s not in your original plan, but just putting 4 inches of soil on top of the clay will give you a 4-inch planting depth. Alternatively, they could just go into the yard debris cart.

Above all, look around the neighborhood to identify plants that are doing well. There are lots of plants that I would like to put in my landscape, but it would just be a waste of money. If they require rapid drainage, they’re not going to survive over time. – Linda Brewer, OSU Extension soil expert.

Testing soil pH is first step in diagnosing blueberry ills

Q: We have three blueberry plants. One is loaded, one is empty and one had a lot of berries until they started shriveling. It also looks like some of the branches died. Other than that, the plant looks very healthy. Any ideas?

I prune them following the OSU Master Gardener videos available online. They get fertilizer (16-16-16) twice a year – once in February and once in September. I do not know the pH of my soil, as they have a weed barrier over the top with drip irrigation underneath.  But we do put garden mulch over the top of the weed barrier, as well as shavings. – Clackamas County

A: You absolutely must get the pH tested.  Blueberries are very sensitive to soil acidity and cannot absorb nutrients if it is outside of the necessary range.  This article has a list of testing labs. Tell them you have a blueberry crop, and they will recommend soil amendments.

Get rid of the weed barrier.  This explains why. There are 24 stem, root, leaf and flower problems with this species as described here and some must be examined in a lab to diagnose the problem.  Before incurring that cost, I suggest that you get the pH/nutrient test and let us know what it says so we can proceed.

In trying to compare the stem lesions with known pathogens, I am afraid that this plant has one of two fungi described here and here. You should immediately remove and destroy the branches with these cankers.  Do not compost!  The second fungus is controlled by the Bonide Captan fungicide but will not be effective until next year prebloom through the end of bloom. – Kris LaMar, OSU Extension Master Gardener

Older rose canes can be pruned now

Q: I have sprayed my rose all over twice with a copper fungicide in the last two weeks but it doesn’t seem to be getting any better also seems to be growing in clumps. I’m sure that is a pruning issue. Should I clip parts of it away now or just wait until it’s dormant and cut it all back? – Columbia County

A: Overall your rose looks relatively healthy, the new growth looks good. I see a bit of disease on older growth, but fungicides will only protect new growth, not remove disease that is already present. If there are diseased canes, you can remove them. You could also prune out the clumped area if you like; do so when it is dry, so you don’t spread disease. Lastly, if you can avoid overhead irrigation and improve air movement (the pruning may help) that can improve the disease issues in your plant. – Heather Stoven, OSU Extension horticulturist