Questions about different grasses and grass alternatives for the Portland, OR area.

Asked August 27, 2018, 4:51 PM EDT

Hi, I have some questions about different grasses and grass alternatives for the Portland, OR area. 1. I'm interested in 4 different grasses and would like to know which one(s) would be expected to work best in soil that is south facing, well-drained, and in full-sun: Buffalo grass, which may outcompete weeds and I think will grow 4" to 6" tall, but develops thatch and turns brown in winter. Bent grass (colonial or creeping?), which may also outcompete weeds, but I think grows much taller than Buffalo grass, and also develops thatch and turns brown in winter. Perennial rye grass (maybe RPR?), which I think won’t outcompete weeds (not even the RPR), will grow 8" to 10" tall, and not develop thatch. And fine fescue, which I think also won’t outcompete weeds, will grow 6" to 12" tall, and also not develop thatch. Also, what about using sedge (Carex praegracilis or carex pansa) as a lawn substitute? I think both of those varieties will grow 6" to 8" tall, should outcompete weeds, and shouldn’t develop thatch. I'm also interested in planting dwarf mondo grass under a magnolia in our curb strip (also well-drained, full-sun). Is that doable? 2. Trifolium repens var Pipolina vs Trifolium repens var Pirouette - what's the difference? Is one taller or bigger than the other? What's the difference between microclover and miniclover? Is there any difference? How noticeable is it (my wife wants NO clover, so it's got to be inconspicuous or she'll veto its use). 3. Which of the grasses above would miniclover/microclover work best with? 4. Thoughts on Mycorrhiza? 5. Thoughts on corn gluten meal as both a pre-emergent herbicide and a slow-release N fertilizer (especially the liquid version)? 6. Thoughts on in-line liquid fertilization through the irrigation system? 7. Thoughts on Milorganite? I have a small front yard and three areas in the curb strip where I could plant various options to see which one(s) will do best in my yard’s micro-climate. If you could help narrow the options down a bit before I do that, I’d much appreciate it. Thanks, Morris

Multnomah County Oregon

3 Responses


For the grass area, are you wanting to keep it mowed?

I have not heard of people using buffalo grass in a lawn setting. Un-mowed, it would make a nice meadow with clumps of perennial grass mixed with other grasses and plants. If you want a lawn substitute, consider a "Meadowscape" approach:

If you plan to mow, then the typical grasses used in the PNW are perennial rye grass and fescues. For a sunny spot, a mix with perennial rye grass and fescues would work. This mix will stay green if you give it water during the summer and fertilizer several times per year. With a lawn mix, if you water, fertilize, and mow at 2" or a bit more, it should remain competitive with the weeds.

Creeping bentgrass can make a nice drought-tolerant lawn, but it needs to be mowed at 1" with a reel-type mower (push mower work). Also, regardless of whether you plant it, bengrass will move in on lawn areas pretty quickly, especially if you do not use fertilizer.

Here is a great publication on lawn establishment/renovation:

I have not heard of using carex as a lawn alternative.

The dwarf mondo grass under a magnolia tree will work. You will need to water the grasses to get them established even if you don't water the tree now.

For the clovers, including them in a lawn mix looks nice and also reduced the overall nitrogen needs of the area. The microclovers and miniclovers (same idea, but probably trademarked) blend in nicely and are not very noticeable.

White clover (the weed) will move into lawn areas that are low in fertility. To keep them out, fertilize the lawn and keep the grass lush and green.

If you add compost to the soil as you are preparing the site, you probably won't need to use mycorrhiza.

Corn gluten meal is not an effective pre-emergent herbicide in the PNW, but is a good plant-based form of N fertilizer.

If you already have an in-line irrigation system, then incorporating fertilizer into that can work well. You'd want to make sure to flush/clean the system to avoid clogging the emitters with salts and solids.

As a slow-release fertilizer, milorganite is a good choice to keep a lawn looking green. Use it 3-4 times per year. Make sure to fertilize when you install or renovate a lawn.

I hope that this response helps you to make an informed decision.

Please let me know if you have other questions.


Hi Weston,

Thanks for your quick reply. I do plan to keep my lawn mowed. From what I've read (thanks for the links, btw) it seems that bentrgrasses will easily take over rye and fescue if I'm not careful. I understand the need to regularly irrigate, fertilize, and mow at 2" or higher if I use rye and/or fescue (I plan on mowing to a height of 3"). But it seems like I might still need to overseed to keep the bentgrass away, is that right? If so, is this typically done annually to keep a nice-ish lawn? I'm not looking for the best lawn on the block, but would like it to look nice.


Hi Morris,

Maintaining good fertility, irrigation, and mowing high are the best ways to keep turf grass competitive with broadleaf weeds and creeping bent grass. Bent grass grows best in low fertility situations.

And yes, overseeding every year or so is also recommended to keep the species of grass that you want. And if you have bare spots, overseed right away.

Good luck!