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misslemonverbena

Planting under oak tree

misslemonverbena
19 years ago

Hello fellow gardeners,

I am not new to gardening, but I am new to Oregon, and new to my particular garden site. Just bought my first home & want to do this right. I could really use some help. My yard is almost entirely within the canopy of a very magnificent old oak tree. I have been told by a landscaper and a couple of arborists that itÂs a pin oak, a scarlet oak, a white oak, and on & on. From my own research I think itÂs probably a northern red oak, quite common in Portland I hear. I called the University of Oregon Master Gardeners line in Clackamas County for advice and was told that oak trees are allelopathic in nature and that it will be a struggle to plant anything beneath it. I asked for suggestions on compatible plants and he just pretty much said nothing will do well. I have never felt so shot down or discouraged in my gardening life. I have heard of walnut trees being toxic to other plants but not oaks. From what I could learn on the internet oaks give off a chemical substance called coumarin that discourages herbs and grasses. Does this mean herbaceous perennials? I would love to hear from any others who garden under oak trees in Portland. My understanding of allelopathy is that itÂs a way that a plant "protects" it territory, meaning making it difficult for other plants to compete for nutrients by exuding a chemical through roots and fallen leaves... There has got to be a way around this. I was hoping to create a dry shade garden that encouraged bird and butterfly habitat. Do you think I should post this in any other forums? (I am also new to the gardening forums). Are all Master Gardeners that darn mean? Thanks for your help. Oh! By the way Master Gardener also told me not use the fallen oak leaves in my compost. This advice seems totally bizarre to me, but then IÂm from California so IÂm more than willing to look stupid. Sorry this is so long.

Comments (21)

  • misslemonverbena
    Original Author
    19 years ago

    Thank you for your reply cantstopgardening.Just the fact that you are growing begonias in wisconsin makes me smile. I just realized I foolishly posted this in Northern Gardening instead of Northwest gardening. My aplogies folks.
    I will try reposting in Nothwest to see if someone has a similar situation.

  • casper1
    19 years ago

    I go out of my way to procure "OAK LEAVES". I ask my friends to please save them for me in plastic garbage bags. I use these bags as insulation for my "banana trees". In the spring, when the insulation is no longer needed, the leaves are shredded,put into the compost, or used as a mulch on my "Rhodo bed". I would suggest to you to enquire about Rhodos, Azaleas, kalmias, and other ericaceae plants. You have the type of situ that a lot of us envy. RAI.

  • cantstopgardening
    19 years ago

    Now, now, misslemonverbena, don't rub it in, I know you probably get to grow begonias like they really should be grown. ;-) Who wants five foot tall begonias and all that warm weather anyway? I like freezing my tucuss off. Really!!

    (just in case you didn't hear the teasing in my voice, it's there. Oregon is soo beautiful. And you probably don't own a snowshovel.)

    Happy gardening.

  • Julie
    19 years ago

    Hey there Misselmonverbena!
    I know I live in MN, but I wanted to share with you that my favotite gardens in my yard are under huge oak canopies! I even have sun loving roses blooming just under the edges on the south side. The oaks do not "steal" as much moisture as pines or lilacs. Their roots go deep and do not hinder even shrubs! Many shade to partial shade plants reside under my oaks, even in zone 4!!
    The leaves do not break down fast like many other leaves. So to some folks, that is a bad thing. Not so to many others. They add friability to the soil's compostion even if they take a little more nitrogen to break down. As mulch and path liners, they work very well also.
    Do not hesitate to try anything shade tolerant under the canopy of your oaks. I have added sky chairs to my larger oak's branches as well and have created a "room" to relax and enjoy.
    Best of luck to you!
    Julie

  • ofpill
    19 years ago

    My garden is partially covered by an oak Canopy and I have noticed no problem! My dad did give me dire predictions but I went ahead and put my veggie garden there anyhow (lettuce, spinach, onions) under the shady bit and they grew beautifully! It is a red oak, I believe.

  • mkirkwag
    19 years ago

    Sunset has a section on what grows well under oaks. Needs to be drought tolerants, as you shouldn't water around oaks.

    I've heard that thing about oak leaves too. I know there's a good deal of concern over sudden oak death syndrome (which comes from leaving your oak lying on its back); some people may feel that this is a way to spread the fungus. More likely it comes from the chemicals released by maple and oak leaves in the rotting process that inhibit seedling growth for a few months. If it's completely rotted, there shouldn't be an issue. The other thing is that oak leaves go into the compost as nitrogen rather than carbon, at least when they're fresh. Not sure about brown ones. Most leaves go in as carbon whatever their color, which always puts me off. It doesn't seem fair.

  • sheryl_ontario
    19 years ago

    You may have to raise the bed under the tree a bit, to get the new plants off the ground where the tree roots steal all the nutrients and water, at least until they get established. I'd feed them a lot more than your regular garden, too, because the tree roots take so much from the soil.

  • tomyslady
    18 years ago

    I live in Fl. any suggestions on what kind of flower or ground cover under my Oaks?
    Thank you,
    Lorraine

  • ContraryMaryOR
    18 years ago

    20 years ago, when I moved to my home in Southern Oregon, I didn't know better, and being the home of Jackson & Perkins Roses, bought 20+ orphan roses at .99 each. I planted most under my large oak tree. My roses are huge now, in a variety of color, though the ones farther from the trunk are larger, some reaching 10 feet! I have an English garden in the front and my oak is the center of my garden. People always comment on my roses in their walks up the street. Also, I am horrible about leaving the leaves on the ground in the fall. I usually just rake them lightly in the spring and cultivate the rest into the soil with bags of manure. Though there are many things I can't grow under my oak tree overs are wonderful. Bleeding hearts, strawberries as ground cover, (I fight English ivy and it has won many a battle) daisies, marshmallow plants, four-oclocks and on the edge of the oak shade, smaller varieties of sunflowers. I grow pumpkins that I train through my white picket fence to trail on the outside of the fence to decorate for fall. I don't know why, but they grow beautifully under the oak tree.

  • shapiro
    18 years ago

    We are in Eastern Canada and have something called a burr oak on our property. It is probably 25 to 30 feet tall now and we are very proud to say we grew it from a tiny plant found in our yard, as big as a pencil (with acorn still attached in the soil). That was maybe 16 years ago. Directly under our magnificent burr oak, some plants have naturally taken residence: an elderberry shrub and lots of blackberries, which we figure got there in bird droppings. At blackberry time, we pick a huge soup-bowl full each day. Moral of the story: learn from Mother Nature, go with the flow of what plants are happy in your neighbourhood.

  • wpooh
    14 years ago

    This is my second year for these hostas under my great Oak
    {{!gwi}}

  • aberberis
    14 years ago

    I found this website to be extremely helpful in deciding what to plant under Oaks. Check out the dos and don'ts at the end!

    Here is a link that might be useful: Las Pilitas oak info

  • coldinmn
    13 years ago

    I don't seem to have any kind of problem planting things under my oaks (pin and burr). I believe it's more of a sunlight availability issue than anything else. Amy

  • oklahomamusicteacher
    12 years ago

    I have huge pin oaks, about 65 yrs old. Nothing will grow under them, including any kind of shade grass or ground covers. Now the roots have gotten under my flower beds in front of our porch. We also had horrible drought last summer in Okla. I have huge patches in my front yard where there is just ugly red dirt! Please help.

  • lo1s
    8 years ago

    Just finished a Master Naturalist course. I chose this over Master Gardner in order to learn which plant goes with which. Also learned a lot about moisture and micro climates. I think the key with your oaks is to find some oaks in the woods and have someone identify what is growing there. Nature had this all going really well before we even got here and started putting in yards and cultivars.

  • Sherwood Botsford (z3, Alberta)
    8 years ago

    I've had no problem with weeds growing in my potted oak trees. I suspect that the person who gave you advice was getting mixed up with the walnut family which all are seriously allelopathic.

    Oaks fall broadly into white oaks, and red oaks. (It's confusing that there are individual common names that match) The white oaks have rounded lobes on their leaves, the red oaks have pointy tips. Pin oak is a red oak. Bur oak is a white oak. Once they are big enough to shed acorns you may be able to better tell.


    In passing: White oaks require no chilling period to germinate. One tree grower comment that they germinated on their way to the ground. Red oaks need to either be planted in fall, or stratified for several months.


    Most oaks produce a big crop (mast crop) every 3-4 years, and not many acorns in between. This is a strategy to try to keep some from being eaten by squirrels. Often all the oaks in a region (of the same species) will produce a big crop in the same year. It's a conspiracy, I tell you.


  • PRO
    Landscapes by Tom LLC
    8 years ago

    Here's another little 'trick' that may be interesting to you. The advice you got from others is great, and here is one more thing to try. Dig a hole to fit a large plastic pot in. Any size pot will do, but perhaps consider a 5 or 7 gallon size. Then put that pot into the hole and backfill around it. THEN, put another pot inside that pot with good soil and your plant. Annuals work great in this application. The inner pot can be easily removed each year and new soil added each year. Make sure you water properly. When the annuals grow, you won't see the pot anymore.

    On another note: Oaks tend to make the soil around them shady and acidic. Two perennials that work well in this environment are hosta and astilbe.

  • kjbbonn
    7 years ago

    I have six large white oaks in my yard and I live in the Willamette Valley in Oregon (lucky in every way). Oaks are allelopathic but certain plants in Oregon are adapted to grow near and under the trees. Ferns, hostas, heucheras all grow under Oak trees naturally in Oregon. The trees are very sensitive to water especially along the base and mushrooms will grow on the base of the trunk as well as the root lines if irrigated/watered heavily. It is important to keep plants a distance away so that water doesn't creep onto the tree base. The roots spread equally about 3 feet down with some deeper rooting at the center - one fell in the oak grove behind my house last winter...very unusual. It is important not to disturb these roots when planting around the tree as injured roots make the tree more susceptible to disease. I have planted Astilbe, coral bells, azalias, rhododendron, Hydrangeas, heliotypes, forsythia and hellebores, coleus and begonias in addition to plants mentioned previously, under the canopy of the oaks, but I have so many I have a larger area to plant in without disturbing the trees. I am trying Japanese Anemone, but it is poisonous so it requires more care to assure animals (dogs, cats) don't get into it. These plants do well in dappled shade under the oaks rather than total shade. I try to supplement my soil with mulch every year. I carefully cultivate by hand the 7 foot by 45 foot garden under my trees with a special rake to break up the soil, add in commercial mulch and organic soil by hand and use a drip watering system with small water lines going to the base of each plant to prevent over watering. The first year is the worst, it gets better as the soil gets more an more conditioned, especially because my soil is a bit "clay" like. Hope this was helpful.

  • lo1s
    7 years ago

    Get in touch with Oregon Master Naturalists if Oregon has that. Our Virginia Master Naturalists are terrific. They have a different point of view. Also, the Pileated woodpeckers love our White Oaks. Over 50 species of birds and insects call the White Oak their home. Our poor neighbors down the street have had a gorgeous White Oak in front of their house and though they were very pleased with it they planted stuff under it and installed a sprinkler system for their grass, then ripped out any moss that was growing naturally in their lawn. The tree is slowly fading away. So sad. The trick is to allow a forest floor to accumulate in the vicinity of the tree. Nature will bring in what the trees need. So happy for you.


  • Deborah lippitt
    6 years ago

    Are you sure it isn't a Garry oak, Oregon White Oak? That is what makes up most of the oak savannas in Oregon. Look for plants that thrive in dry shade conditions. You can kill the tree with too much water..watering water hungry plants.

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