Weeds: Friend or Foe? – A surprising discovery regarding co-planting

Written by Kari Conklin

It’s a rainy morning in Hampton, Virginia. We’ve been experiencing a number of days of rain, which can hamper business when you’re in the mowing and lawn care industry. However, once it clears, it’s game on! Grass goes nuts and so do the weeds. Customers are calling left and right asking if we can move them up in the schedule. Pandemonium really for our small operation. But while we have the rain, it’s peace and quiet for a time, so it’s a perfect opportunity to research and write.

This week we’ve been focusing on the topic of companion planting (co-planting for short). It’s the idea that planting some plants close to one another can be beneficial, or disastrous, depending on the type of plant. This was a suggested topic by a member of our community, who we are so grateful for! We have been learning much as we’ve transitioned into this business, and we want our community to learn right along with us. So, let’s start with the basics about co-planting.

Co-planting is especially beneficial in the garden, where pairing plants together can help them to thrive. Flowers that attract certain helpful insects, and deter other pests, can add beauty and function to your garden. Certain plants paired together can provide a structure to grow on or shade for roots that need to stay moist. A number of resources are linked throughout this article which provide guidance on which plants you could use, but in general the benefits of co-planting can include:

The other side of companion planting, is allelopathy. Allelopathic plants chemically impede the growth of others. While these can be used in a positive way for weed prevention, they tend to kill everything else around them as well. Limited research has been performed to measure the effects of these plants and their level of impedance. However, surprisingly, there may be times when those unsightly weeds are helping you more than you know.

Weeds have a bad rap. They can take over your beautiful landscape, growing out of control, and leave you feeling helpless and ugly (your lawn and garden that is). In a world of neat and tidy perfection, this is simply unacceptable. However, perhaps if we better understood the benefits that some weeds can offer, we would reconsider the lengths we go to eradicate every last one. Weeds do have benefits such as:

  • Providing flowers to improve pollination
  • Bringing deep nutrients to the soil surface
  • Providing natural “mulch” to keep soil moist
  • Leaving nutrients behind after decomposition
  • Holding top soil in place
  • Breaking up hard soil

Still don’t believe that weeds can be your lawn and garden companions? How about the stinging nettle? The stinging nettle has been shown to improve the growth and vigor of neighboring plants and helps them resist spoiling! And those dandelions that are so hard to pull? Their deep tap-roots can break up compacted soil and provide an easier path for other plant roots. Other helpful weeds of note include prickly lettuce, spiny sow thistle, cockleburs, nightshades and Queen Anne’s lace. While you don’t want to let these guys crowd the rest of your plants, with moderation they can help your plants thrive. And for the weeds that had to go… eat them!

Lambs-quarters, yellow dock, young dandelion leaves, purslane, chick-weed, land cress and sorrel might as well be spinach due to their nutrients. So, eat up! When looking up “weed recipes”, however, we do suggest staying away from those that mention the cannabis plant. In fact, search for the weeds by name just to be safe. You have been warned.

If you don’t know what you’re looking for when your hunting for edible weeds, we’ve included some visuals below to help you in your dinner preparation.

Lambsquarters is an excellent source of protein, vitamin A and B, riboflavin and folic acid.
Yellow dock or Curly dock is a bitter “herb” that stimulates appetite and normalizes digestion.
Purslane has a mild lemony flavor with a hint of pepper. Half chewy and half crunchy. Photo courtesy of Eve Fox, The Garden of Eating blog, copyright 2019, all rights reserved.
Dandelion is easy to identify, but very bitter if not prepared correctly.

If it makes you uncomfortable thinking of letting a few weeds here and there aide as companions to your socially accepted plants, and eating them makes you sick to your stomach, perhaps allelopathy is for you. Allelopathic plants impede other plants either through their roots, decomposing leaves, pollination, volatilization, or leaching. Some well known allelopathic plants are black walnut trees, pine trees, fragrant sumac, rice, peas and sorghum. Want a nice clear bed of mulch with minimal weeding? Plant a black walnut tree or pine tree and surround it. There are some plants that will tolerate the chemicals they put off, but beware, even if the tree is cut down, the soil will remain toxic to certain plants for years to come. The key is to plan for these things.

Companion planting is something that should be considered when planning any landscape project or garden. Start with what you want grow, and gain an understanding of what each plant needs. Use other plants and flowers to provide for those needs, and ensure they are compatible. Hopefully some of the links provided throughout this article and compiled down below will provide enough details to help you be successful in your planning process.

This article was last updated on 6/5/19.

References:

  1. “Garden Wisdom: How to Plant A Companionable Garden” windowbox.com, https://www.windowbox.com/resources-links/companion-planting-chart-for-vegetables .
  2. “Underplanting Roses – Companion Plants for Roses” Gardenia Creating Gardens, https://www.gardenia.net/guide/Underplanting-Roses .
  3. Jauron, Richard. “Pollination Requirements for Tree and Small Fruits” Horticulture and Home Pest News, Iowa State University Extension and Outreach, March 2, 1994, https://hortnews.extension.iastate.edu/1994/3-2-1994/pollen.html .
  4. Tilley, Nikki. “Allelopathy In Plants: What Plants Suppress Other Plants.” Gardening Know How, 06/27/16, https://www.gardeningknowhow.com/garden-how-to/info/allelopathic-plants.htm .
  5. Waterworth, Kristi. “Incompatible Garden Plants: Learn About Plants That Don’t Like Each Other” Gardening Know How, 04/04/18, https://www.gardeningknowhow.com/edible/vegetables/vgen/incompatible-garden-plants.htm .
  6. Langley, Sue. “Allelopathic Plants….what? “I want to be aloooone”.” Sierra Foothills Garden, 04/10/11, https://sierrafoothillgarden.com/2011/04/10/allelopathic-plants-what-i-want-to-be-aloooone/ .
  7. Ferguson, James J., Rathinasabapathi, Bala, and Chase, Carlene A. “Allelopathy: How Plants Suppress Other Plants1.” EDIS, University of Florida IFAS Extension, https://edis.ifas.ufl.edu/pdffiles/HS/HS18600.pdf .
  8. Tran Dang Xuana , Tawata Shinkichia , Tran Dang Khanhb , Chung Ill Min. “ Biological control of weeds and plant pathogens in paddy rice by exploiting plant allelopathy: an overview .” ResearchGate, Science Direct, 08/11/04, https://www.researchgate.net/publication/222018070_Biological_control_of_weeds_and_plant_pathogens_in_paddy_rice_by_exploiting_plant_allelopathy_An_overview .
  9. Lohmiller, George and Becky. “Companion Planting Guide Companion Planting Tips, Plant List, and More.” The Old Farmer’s Almanac, 02/10/19, https://www.almanac.com/content/companion-planting-guide .
  10. Sides, Susan. “Discover Beneficial Weeds in the Garden.” Mother Earth News, July 1987, https://www.motherearthnews.com/organic-gardening/beneficial-weeds-zmaz87jazgoe .
  11. Kathi. “Lambsquarters.” Oak Hill Homestead, https://www.oakhillhomestead.com/2014/05/lambsquarters.html .
  12. Bean, Geneve. “Yellow Dock.” The Herb Hound, 04/23/13, http://theherbhound.blogspot.com/2013/04/yellow-dock.html .
  13. Fox, Eve. “Eat Your Weeds – Purslane.” The Garden of Eating, 08/11/14, http://www.thegardenofeating.org/2014/08/purslane.html .
  14. “Edible Wild Plants – Dandelion Greens.” Sensible Survival, Blogspot.com, 04/11/11, http://sensiblesurvival.blogspot.com/2011/04/edible-wild-plants-dandelion-greens.html .
  15. A.K.M. Mominul Islam . “ Allelopathy of Five Lamiaceae Medicinal Plant Species.” ResearchGate, June 2014, https://www.researchgate.net/publication/322626260_Allelopathy_of_Five_Lamiaceae_Medicinal_Plant_Species.

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