In Praise of Weeding

by Bob Shaw, EMGV

Weeds, I once thought, are a curse. Perhaps the Lord, looking down on Carolina and musing that it was just too nice, sent Gabriel to bring us extra hot weather and especially bountiful crops of weeds[1]. I still think weeds are a curse but have found with them, now and then, a little satisfaction. 

Time is important. Before I retired I weeded when I could, but I was often away and, by mid-July, had surrendered my yard and gardens and, when I passed by them, looked the other way. Now I have time to keep after weeds and have discovered a sort of tipping point:  After several years of faithful but not obsessive weeding, I now hold the weeds at bay and mid-summer no longer looks so bad.

During weeding, one can pass into an agreeable meditative state or one can wear a portable radio and multitask. One can relax. A serious mistake is unlikely unless you are weeding someone else’s yard and, anyway, nature is so forgiving.

I don’t eschew herbicides; but use them sparingly – on that dratted Bermuda grass, say.  Some weeds, especially after rain, come out, root and all, rather easily;  crabgrass, the promiscuous Japanese stilt grass, and henbit for example. And getting down close to the ground to weed shows us so much more; the weeds themselves and their habits, occasional interesting bugs (very useful if we discover a trail of ants about to foray into our house). Early this spring, during weeding, I found myriads of beautiful red and black box-elder bugs under our maples. Sometimes, joy of joys, we may encounter a really good bug, perhaps a praying mantis.

Let’s give weeds their due – remarkable, aren’t they? Looking over a bed that seemed, at first, weed free, I spot a weed and, pulling it up, spot another close by. Soon, a forest of weeds has appeared where none seemed to be just a minute before. And how do they spring up so promptly after a rain? Coexistence isn’t an option – weeds, like Japanese beetles, don’t know about sharing.

In life we seek positive results. And so it is with weeding:  What is more positive than standing up from a pile of rooted-up weeds and admiring an immaculate garden bed?  Even better, sometimes one can put that pile into the compost bin and turn it into useful stuff.2  If only the rest of life were like that.

Photo captions, clockwise from upper left: Box-elder bug (credit: Whitney Cranshaw, Colorado State University, Bugwood.org), henbit, Japanese stiltgrass, Bermuda grass.


References

1 Lucifer may have participated.  If lawns are in hell, they are planted in Bermuda grass.  And a close reading of Job would surely turn up a reference to Bermuda grass.

2 Avoid composting weeds if they have begun producing seeds.  NC Extension Gardener Handbook, What not to compost https://content.ces.ncsu.edu/extension-gardener-handbook/2-composting#section_heading_5138

Photo credits
https://www.turffiles.ncsu.edu/weeds-in-turf/henbit/ https://www.turffiles.ncsu.edu/grasses/bermudagrass/
https://www.turffiles.ncsu.edu/weeds-in-turf/japanese-stiltgrass/
https://www.insectimages.org/browse/detail.cfm?imgnum=5024073

I must Stop the Mock Strawberry (Duchesnea indica)

By Wendy Diaz, EMGV

Last year, I noticed a spreading wildflower around the base of my beautyberry bushes (Callicarpa Americana) in a perennial bed along the south side of my house that I originally thought was Wild Strawberry1 (Fragaria virginiana). It appeared amongst my creeping Jenny (Lysimachia nummularia ‘Aurea’), which I was using as a ground cover. 

Mock Strawberry colony of plants covering ground of ornamental flower bed. Photo by Wendy Diaz on May 6, 2019

This year, it has taken over the bed and migrated into the lawn and even the aggressive creeping Jenny has lost its battle with this plant, which now covers every plant in the bed that isn’t higher than five inches. A lesson that I should have learned a long time ago … if the gardener ignores a few weeds in the garden, the gardener risks bigger issues in the future. The culprit, as it turns out, is a perennial weed commonly called Mock or Indian Strawberry (Duchesnea indica)2,3and not the native wildflower, Wild Strawberry4. The relatively sudden appearance of this plant in my yard is likely the result of birds eating drupes elsewhere and spreading them to my yard2.

Creeping Jenny has been covered by Mock Strawberry in ornamental bed. Photo taken by Wendy Diaz on May 6, 2019

Mock Strawberry (Duchesnea indica)

Mock strawberry is an herbaceous perennial plant of a height between three and eight inches and spreads by runners or hairy stolons3, 5 into large colonies of plants over time. Each plant consists of small trifoliate basal leaves with long petioles that develop from a root crown2. Each leaflet is about one inch across and elliptical with rounded toothed lobes5. Its five-petal yellow flowers of about 0.5-inch diameter appear in spring and develop into tiny edible red tasteless fruit or drupes that are held upright2. Small red seeds form on the bumpy surface of the fruit. It prefers moist soils and partial sunlight and can adapt to regular mowing because of its low growing habit2. It was introduced as an ornamental plant from south Asia.

Five-petal yellow flower of the Mock Strawberry. Photo taken by Wendy Diaz on June 20, 2019
Trifoliate basal leaves and red fruit or drupes of Mock Strawberry. Photo taken by Wendy Diaz on May 6, 2019

Control

To help reduce Mock Strawberry lawn encroachment, it is recommended that one improve surface drainage, aerate when needed and conduct infrequent watering5. If the gardener is interested in chemical control, the recommendation for both pre-emergence and postemergence control formulation is provided in detail on the NC State TurfFiles website5.  In my perennial bed I have decided to control it by hand weeding and mulch. 

Comparison to Wild Strawberry

Wild Strawberry or Scarlet Strawberry can make a desirable ground cover in woodland gardens with some wildlife value1, 4 and it can control erosion on slopes. Mock Strawberry is easily distinguishable from the native Wild Strawberry because its flower is yellow and the Wild Strawberry has a white flower. Other differences include lower growing and smaller leaves of the Mock Strawberry and the drupes are erect. The Wild Strawberry drupes tend to hang downward and the teeth on the leaf edges are sharp-pointed rather than rounded. Best of all, the fruit of the Wild Strawberry is juicy and with a pleasant sweet-tart taste whereas the Mock Strawberry is bland with a dry texture.

Your yard may not have ideal conditions for Wild Strawberry as a ground cover but nevertheless cultural control of Mock Strawberry is more desirable than letting it takeover your ornamental beds and crowding out more desirable lower growing plants.

References

  1. http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=291715&isprofile=0&=

2. https://www.illinoiswildflowers.info/weeds/plants/mock_strawberry.htm
3.  https://plants.ces.ncsu.edu/plants/all/duchesnea-indica/

4. https://www.ncwildflower.org/plant_galleries/details/fragaria-virginiana

5. https://content.ces.ncsu.edu/indian-mock-strawberryor

https://www.turffiles.ncsu.edu/weeds-in-turf/indian-mock-strawberry/

Ground Covers as Weed Control

by Andrea Laine, EMGV

After several years of trying to stay ahead of the weeds in my landscaped beds, I am coming around to an option I had not seriously considered before: planting ground covers as weed control.

Weeds

A variety of annual and perennial broadleaf weeds consider my yard home year round. Most of them I deal with by manually pulling. Dr. Joe Neal, professor of weed science at NCSU, recommends a frequency of every two to three weeks. Call me crazy, but I have never minded hand weeding. It feels meditative while I am doing it and afterwards, too, when I look upon my tidy garden.

Unfortunately, hand-pulling does not work for creeping woodsorrel (Oxalis corniculata L.). Even after a good rain and using a weed digger, it is difficult to get the root up on a younger plant. I find it easier to let it grow a bit which gives me more plant above ground to grasp and pull. But allowing any weed time to mature is dicey: weeds multiply so quickly and aside from being unsightly, rob your favored plants of moisture and nutrients in the soil. Encroachment is inevitable with woodsorrel as it spreads by rhizome, stolon and/or rapidly germinating seeds.

Ground covers

I used to view ground covers as boring plantings; something you chose for a spot where it was difficult to grow anything else, or something non-gardeners or commercial properties planted to paint a spot green and call it landscaped. (Pachysandra comes immediately to mind.) But looking out my kitchen window last November at the way a few biennial columbine plants (Aquilegia canadensis) have reseeded so profusely over just a few years and now expertly cover a large part of the ground in one bed (i.e. no woodsorrell there), I am beginning to understand the concept and consider the possibilities.

ColumbineCover
Columbine isn’t traditionally considered a groundcover but it does the job nicely. All photos by A. Laine.

Ground covers are plants that grow relatively close to the ground and spread freely to create a mass planting. The denser they are, the better they will be at shading the ground, thereby robbing weed seeds or rhizomes in the soil of the light needed to grow. If desired for weed control, seek out evergreen ground covers.

Columbine isn’t traditionally considered a ground cover but it does the job nicely. Some common ground covers are already established in my landscape; pictured below left to right they are: golden creeping jenny (Lysimachia nummularia ‘Aurea’ ), creeping juniper (Juniperus horizontalis ), oregano (Origanum heracleoticum ‘Greek’ ) and Mrs. Robb’s bonnet (Euphorbia amyglaloides, ‘robbiae’).

A blank canvas

My thoughts of “too much columbine” have turned to “need more variety of ground covers.” Ground covers will be the new blank canvas. I am not choosing ground covers instead of more ornamental perennials and shrubs. I am choosing ground covers over open soil or a blanket of mulch which can be expensive and labor intensive when used for large spaces. Rather than fretting over too much columbine, I will consider it a placeholder and an organic mulch. When I am ready to plant something among it, I will simply edit out some columbine and insert a showier ornamental.

Where you have stubborn weeds, consider planting a more attractive ground cover. More plant suggestions appear in the links below.

Sources & Further Reading

About weeds

Identifying specific weeds:  https://projects.ncsu.edu/cals/plantbiology/ncsc/containerWeeds/list.htm

https://content.ces.ncsu.edu/are-you-weeding-frequently-enough-to-prevent-weeds-from-spreading

Creeping woodsorrel: https://plants.ces.ncsu.edu/plants/all/oxalis-corniculata-l/

About Groundcovers

This link lists dozens of groundcover suggestions for Georgia landscapes. Almost all will also survive in Durham County (Hardiness Zone 7).  https://secure.caes.uga.edu/extension/publications/files/pdf/C%20928_2.PDF

At heights of three to 12 inches, miniature roses can be groundcover:  https://content.ces.ncsu.edu/roses-for-north-carolina

Low-growing junipers make excellent groundcovers: https://content.ces.ncsu.edu/junipers-in-the-landscape

More groundcover plant ideas: https://www.missouribotanicalgarden.org/Portals/0/Gardening/Gardening%20Help/Factsheets/Ground%20Cover%20Plants66.pdf

Strategize to Beat Weeds

by Marty Fisher, EMGV

I have a lovely patch of chocolate chip ajuga—it has dark purple evergreen leaves and blue flowers in early spring. It spreads stoloniferously and lately, it has begun to drift through my perennial bed, establishing small colonies in attractive drifts. It’s a nice companion to red and yellow pansies in the spring, fades away to let perennials shine in the summer, and provides a fluffy green and purple texture to brighten winter.

So, just imagine my horror this summer, when hundreds—I kid you not—hundreds of tiny, bright green weeds appeared woven throughout my ajuga like a rampant cancer.

chamberbitter
This is the dreaded chamber bitter, new to my garden this year. It’s also known as gripe weed, leaf flower, or little mimosa. It has yellow flowers on the underside of the leaves. If it’s nestled amongst your perennials as mine was, the only good solution is hand weeding, before it sets seeds and preferably when the ground is soft and wet.

IMG_1062.JPG
Chocolate chip aguga … before infestation with chamber bitter.

There was nothing to be done but spend hours on my hands and knees painstakingly plucking the little suckers out one by one. I discovered the name of my new weed is chamberbitter, which sounded exotic enough to make me feel a little better. It looks a little like a mimosa and has yellow flowers under the leaves. It likely rode in on something I planted, or perhaps one of the many birds I feed graced me with it. I must have missed it last year, and it set seed and multiplied. It is now July, and I am still plucking at it, watering it with my sweat as I go.

This awful experience got me thinking about the strategies weeds use to get into our gardens, gain a foothold, and multiply. They have multiple methods of getting into our gardens—through birds’ digestive systems, in containers from nurseries, or they simply ride in on the wind! One source I consulted suggested removing the top layer of soil from nursery plant containers before planting. This seems like a good strategy, especially for the ubiquitous oxalis! But I can’t think of anything to stop the weed attack from birds or the air…

As happened with my ajuga, weeds like to mingle with existing plants—nestled as close to our favorite plants as possible. This provides protection and makes them harder to eradicate. They also are adept at snapping off when we try to pull them, leaving their roots intact to sprout again. For bigger weeds, I use a Japanese hori hori knife.

The knife can slice into the dirt just at the base of the weed, without disturbing the soil too much. Then you can grab it as close to the ground as possible and pull. Other valuable tools include an old table fork for twisting out the roots of weeds and a fishtail weeder for digging out tap-rooted or bulbous weeds such as dandelion, violets, or dock.

This may come as a shock, but every inch of your garden and mine is chock full of weed seeds. They can lie dormant for years, and all they need to germinate is a little light. When we dig, plant, or even hand weed, we bring weed seeds into the light. So, it’s critical to cover any exposed or disturbed soil with mulch. Two inches of mulch is recommended. More can cut off oxygen to the plants we love. Never skimp on mulch—I would skimp on fertilizer before I skimped on mulch!

The best time to pull weeds is before they set seed, and after a good soaking rain. Once weeds set seed, the battle is lost. You’ll be fighting them for years to come. After a rain, weeds come up easier with less disruption of the soil, and mulch applied after weeding will hold in the moisture from the rain. For really bad weed infestations, the best solution is spraying with glyphosate. But this is not an option in closely planted landscape beds, as glyphosate kills any plant it comes into contact with.

Never put freshly pulled weeds into the compost bin. Heat is the key to composting them. I find it very satisfying to lay them out on my asphalt driveway where I can watch them cook in the sun. Even after they are fully cooked, I’m not brave enough to put them in my compost bin, but sources say, once they are dead and rotting, you can put them in clear plastic bags, leave them in the sun for two or three days, then compost them. (I don’t now that I reallyneed compost all that much!)

We are all busy. It would be great if we could mulch at the best time and weed at the best time. But sooner or later, we all miss the ideal timing. I think weeds know this will happen, and they take full advantage of it. By nature, they are designed to grow and set seed rapidly, the better to evade the gardener and spread their offspring across the land. So, if you can’t get in to fully eradicate them, lop off their heads. This keeps them from setting seed until you can get back in the garden.

I am not sure I believe this, but according to soil scientists, fewer weed seeds germinate in soil that contains lots of compost and organic matter. But it can never hurt to enrich the soil, so good advice regardless! (My perennial bed is full of compost and organic matter, and I have plenty of weeds…just saying …)

My goal every year is to get everything planted, weeded, and mulched before we leave for the July 4th holiday. Then I coast until time to plant winter veggies in early August. I wish everyone a weed-free summer!

So here is a rogues list of plants I have been fighting lately. Only because of its name, tops on my list is Hairy Crab Weed, or Mulberry weed. It is a monstrous weed and it has a distinct smell.

Then of course there is Japanese stilt grass, which is ruining the chances of survival for our native wildflowers. It loves shady woodland environments.

Nutsedge is another candidate for most obnoxious! The best weapon for this one is glyphosate but if it’s in your perennial bed, that’s not an option since the spray will kill your desirable plants. Nutsedge retains a “nut” or a seed, in the ground. After you pull it, it will re-sprout.

IMG_1043So, I guess the bottom line is, weeds are just something we are going to have to deal with. I don’t think you can completely eliminate them but if you set aside a day each month to pull them, you can keep them somewhat at bay. Happy Summer!

 

Resources:
https://www.nature.org/ourinitiatives/regions/northamerica/unitedstates/indiana/journeywithnature/japanese-stiltgrass.xml

https://www.uaex.edu/yard-garden/resource-library/plant-week/mulberryweed.aspx

Guides to identifying weeds:
http://oak.ppws.vt.edu/~flessner/weedguide/

https://weedid.missouri.edu/weedKey.cfm

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A Pesky Winter Weed

By Barbara Goodman, EMGV

Bittercress (Cardamine hirsuta), also known as lamb’s cress, spring cress, wood cress, or flickweed is a member of the mustard family Brassicaceae. It is a winter annual, but can persist year-round in a moist, shaded environment in disturbed areas.

I find it throughout my garden primarily in and along the gravel paths (where I might have tracked it’s seed over the years), and in the moist corners of some garden beds. It also loves my currently dormant raised veggie bed. Since I must garden in high shade conditions on our wooded lot, I have the perfect environment for it. It also loves container pots, so be sure to pull every last little seedling out of plants that you bring home from the nursery.

This pesky menace is native to Europe and western Asia but was introduced and naturalized throughout much of the US and the world. *

SI Exif
photo credit: Oregon State University

As it grows, it demonstrates an upright growth habit with a dense basal rosette. The shoots bearing its tiny white flowers grow up from the center from 3 to 8 inches high. Pull these little devils up by the roots before the seedpods form. When mature, the pod splits open and forcibly expels the sticky seeds up to 6 feet!  One plant can produce 5,000 seeds that can germinate quickly or remain viable in the soil for many years. Hence the clusters that occur. In the gravel paths a scuffle hoe can cut them down, but it is best to pull by hand and get the root. I prefer to garden chemical-free, but I may have to seriously consider a pre-emergent weed treatment in the future.

 

References:
*From ENH1250, one of a series of Environmental Horticulture Department, UF/IFAS Extension.  Original publication date December 2014. http://edis.ifas.ufl.edu/ep511.