Washington: A couple questions about Oxalis oregana

Discussion in 'Pacific Northwest Native Plants' started by ersh99, Aug 25, 2015.

  1. ersh99

    ersh99 Active Member

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    Hi-

    I am planting an area in my Redwood forested backyard and want to create a carpet like feel at the base using native oxalis oregana (I am in Seattle). A couple of questions, I seem to be getting mixed information on if this an evergreen or not (just curious if it dies back in winter). Also, to create that carpet like feel, what kind of spacing would you recommend? Does this plant fill in fast or is it slow to fill in. I believe I have the perfect setting/microclimate for this plant under the redwoods, dry shade, acid soil.

    thank you for any information you might have!
     
  2. Margot

    Margot Generous Contributor 10 Years

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    Your idea of planting native oxalis in you Redwood forested backyard sounds beautiful. You may want to consider planting the odd fern or trillium amongst the groundcover to enhance the picture.

    My experience growing Oxalis oregano is somewhat limited but I have noticed that many such deciduous plants stay green when winters are mild. I grew what I thought was O. oregana rosea when I lived in Burnaby, BC, but have since come to question whether it was a legitimate native plant or even whether it was correctly identified. It was very attractive though with burgundy undersides to the leaves and pink flowers.

    Apparently ( http://www.greatplantpicks.org/plantlists/view/1071 ), there are deciduous and evergreen forms of Oxalis oregano that would be worth checking out. While oxalis may tolerate dryness, it is said to prefer moist situations, at least initially. "Oxalis oregana is best grown in moist to well drained soil with light to deep shade. It will tolerate sandy sites and clay. Once established it is drought tolerant. Oxalis oregana, the evergreen form, is not as vigorous as the deciduous form which can become quite invasive. It does not need to be cut back in winter, but can be to create a tidier appearance."

    Depending on how much you want to spend, I'd plant oxalis about 12 inches apart. Be careful that the soil in is mostly weed-free to start with or you'll have no end of work pulling weeds while the groundcover fills in - and even after.
     
  3. Ron B

    Ron B Paragon of Plants 10 Years

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    Yes if the planting location is too dry this strictly coastal fog belt species will not persist. Also people are often trying to plant things beneath conifers in the first place because nothing else has been able to grow there, it is often typical to have to modify the planting site beforehand - and follow up consistently - to get such places greened up. In this case you might have to install a (shallow as possible, for the sake of the trees) layer of fresh soil, mulch after planting and water the plants every year.

    You might be interested in viewing the plantings of this species at the Kruckeberg Botanic Garden, comparing the situation there with yours.

    http://www.kruckeberg.org/
     
  4. ersh99

    ersh99 Active Member

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    Thank you for replies and advice! I've seen carpets of oxalis amongst the evergreens in certain sections of Bloedel Reserve and it is so amazing! I will take a look at Kruckeberg garden too. With watering, small amount of fresh composted soil and mulch amongst plantings at 12" spacing, any idea how many year so fill in? Just not sure how fast of a grower it is.

    thank you!!
     
  5. TheScarletPrince

    TheScarletPrince Member

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    We are planning on doing a ground cover for our yard as well. We plan on destroying the weeds (by hand, of course) and tilling the entire yard! Going to be fun but a lot of work, the soil should come out really nice.
     
  6. Margot

    Margot Generous Contributor 10 Years

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    Hi SP - in my experience with groundcovers, it is VERY important to plant in soil that is weed-free. It will save you a lot of headaches. One (unrealistic) way to accomplish this is to wait a few years and pull all existing weeds before they go to seed, thus reducing the number of weeds you will have to painstakingly remove from amongst the groundcover. Once established, groundcovers can be very good at choking out opportunistic weeds but that's not the case when they are newly planted. Do not till the soil because that only brings latent weed seeds to the surface. However, you may need to do some digging to eliminate existing weeds with tap roots or rhizomatous roots like dandelions and sorrel. My best advice, based on long experience, is to remove all visible weeds, perennial weed roots and then spread a layer of weed-free soil over the area to be planted. After the groundcover is planted, mulch well with a weed-free mulch. Then you should be able to relax and enjoy it.
     
  7. TheScarletPrince

    TheScarletPrince Member

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    Unfortunately we don't have the funds to purchase enough soil and mulch to cover the entire yard, which is why I am going to clear the weeds and till it. There will still be weeds but it will be much better than it is now. We inherited this yard and it is full of this awful ground-cover weed that grows annoying stickers. Really bad, here is a picture of the stuff!
     

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  8. Margot

    Margot Generous Contributor 10 Years

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    I'm curious about 2 things: what is the name of that groundcover in your photo and, how many square feet or yards are you looking to cover?
     
  9. TheScarletPrince

    TheScarletPrince Member

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    It is less than half an acre and I am still wondering the name of that groundcover myself. Unfortunately, nobody responded when I had asked on here.
    I fear that it may be some kind of herbicide resistant weed that has evolved in the area.
     
  10. Margot

    Margot Generous Contributor 10 Years

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    That groundcover looks a lot like Lysimachia nummularia (Creeping Jenny.) I may be incorrect though because Creeping Jenny likes moist soil and you say yours is dry. Are the flowers yellow? I know it will take time and effort to remove but at least the roots of CJ don't go down too deep. Good luck!
     

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