Get your tree related questions answered by our knowledgable members!

Post a question or a topic for discussion in the forum below

Pin Oaks

Does anyone have any definitive sources they can steer me towards about the difficulty of establishing any vegetation under a close stand of pin oaks?  Our neighborhood association is giving us a hard time about the lack of a lawn under 4 of these allelopathic big guys on our front yard.  They are beautiful, but try as we might, the yard is a mess.

You need to be a member of American Grove to add comments!

Join American Grove

Email me when people reply –


  • I have landscaped successfully under my large live oaks in Florida for years. Yes the soils are much sandier but the shade is the same. Agree with the recommendations for shade shrubs or groundcovers if your neighborhood insists on landscaping under the tree. I have been pleased with a mix of dwarf gardenias, flax lilies, iron men and acuba. The acuba probably will not make it in D.C.however due to the cold temps. Hydrangeas might work also and don't hesitate to incorporate containers/pots also in with the other plants.
  • Teach your "neighborhood association" the value of Oak trees and the wastefulness of turf grass. The best thing to put under trees is wood mulch, something that mimics a natural settings. The extensive root system of a tree will out compete the shallow roots of turf whether it is getting enough sunlight or not. Learn to replicate the sustainability of nature instead of working contrary to it.
  • Depends on where you are located.  Go with groundcovers, with minimal digging to minimize root damage. Limbing up the crowns in winter may help, though pin oak appreciate the shade on their root systems.

  • You might want to look at Ophiopogon (aka Mondo grass) and their dwaft varieties.  The dwarf variety looks like dark green grass, not really walkable, but looks good, very little maintenance and does well in shade.

    "Simply irresistible" is the best way to describe this dwarf version of mondo grass with dark green, grass-like foliage which eventually makes a tight mat in even the worst of conditions. Plant dwarf mondo on 6-12" centers for a wonderful evergreen groundcover. Ophiopogon 'Gyoku Ryu' could best be described as looking like a rich, dark green lawn of pre-mowed grass...what a great idea! - See more at:

    Another selection of plants that make a good ground cover and provide landscape interest is sold by

  • thanks for the reply.  I believe monopolizing light is part of what allelopathy is all about, though I admit I am new to the concept.

    Soil is clay beneath a thin layer of top soil.  We live in D.C.  As I understand it, the pin oak, or Swamp Oak does not do well with growing season irrigation, which is exactly opposite of what most understory vegetation needs, especially during our hot summers.  Plus oaks like acidic soil, while most grasses prefer slightly alkaline.  Again, my understanding is that pin oaks have a thick weave of roots and fungus near the surface which sustains them, and ground covers such as the ubiquitous ivy actually starve them out. 

    A certified Maryland arborist has advised us to have large mulched area around the base of the oaks (10 feet) with only a few understory shade plants for visual accents, but the garden police in our neighborhood association want to mandate a lawn or what they call "greenspace," ignoring the fact that oaks are "greenspace."  Crazy.  It's what happens when unqualified people get a hold of the regulation book, IMHO.  Impossible to educate people who are more interested in preserving their authority than expanding their knowledge.

  • It may not be allelopathy that is preventing robust growth, but dense shade.  Also to best answer your questions please provide: what type of soil, what state do line in, your growing zone.  Irrigation?  Have you thought about shade tolerant ground covers or shrubs?   

This reply was deleted.