Weeds are simply plants out of place, and not all need to be removed. When deciding a weed’s fate, a gardener must consider, among other factors, the weed species, its location within the garden, and the weed’s potential function for its location.
We are taught a garden should be weed-free and that each weed not pulled is a mark against us. In the United States, gardeners spend millions of dollars and millions of hours annually pulling, digging, cutting, spraying, smashing, cursing, hacking, and otherwise declaring all-out war against weeds in their gardens and lawns.
Weeds are plants out of place. This means that the dandelion and the tulip alike could be considered a weed depending on where they grow, how they grow, and the gardener’s tolerance for them in that location.
Gardeners should keep in mind that weeds are simply plants out of place, and that weed species in certain places can be acceptable (and maybe even beneficial).
When a plant is growing in an unplanned place we cannot ask, in absolute terms, “Is this a weed or a flower?”, eliminate those falling in the former category, and still have a sustainable or ecologically-informed approach to gardening. Determining if a weed is worth removing involves more than a simple ‘good’ or ‘bad’ categorization. The gardener must consider, among other factors, the weed species itself, the weed’s location within the garden, and the weed’s potential function for its location in the garden.
Lurie Garden’s Categories of Weeds
Instead of discussing weeds as good or bad, Lurie Garden considers weed species as another part of the garden to be managed. Just as we manage the location and appearance of Echinacea pallida (pale purple coneflower), staff also manages Taxacum officinale (dandelion). At Lurie Garden, weeds fall into the following four categories:
- Plants we never like
- Plants we once liked but are now hard to control
- Plants we leave and use in the garden
- Plants that disturb the design
Even these categories are not absolute. While garden staff and volunteers may remove certain weed species from one area of the perennial planting beds, the same weed may be left elsewhere in the garden because it serves a specific horticultural or ecological purpose in that location. Gardeners should keep in mind that weeds are simply plants out of place, and that weed species in certain places can be acceptable (and maybe even beneficial).
Plants We Never Like
There are certain weed species our horticulturalists and hands-on volunteers never like to see and are religious about removing from the garden. These weeds are aggressive, invasive, and considered noxious. Convolvulus arvensis (bindweed) is a member of the large, taxonomically complex morning glory family (Convolvulaceae). This weed species is a perennial vine that twists its way around upright stems of surrounding plants to reach maximum sunlight exposure. When left unattended, their growth results in large, dense mats of vines that shade-out surrounding plants. The round white flowers of bindweed may look appealing in the garden, but they will go on to produce a multitude of seed to spread this aggressive weed around the garden.
Lurie Garden staff and volunteers hand dig bindweed plants as they are found in the garden’s perennial beds and shrub planting areas. Bindweed is a deep-rooted plant, so pulling is often ineffective and results in multiple plants arising from broken root segments. Herbicide treatment for bindweed can be effective; however, no synthetic chemicals are used in Lurie Garden for the control of weed species in accordance to the garden’s sustainable and ecologically-informed management philosophy.
Another weed species regularly removed by Lurie Garden is Taxacum officinale (dandelion). Many gardeners battle dandelion in their garden and lawn spaces, so the fact that Lurie Garden removes this weed species from the garden may not be surprising. However, dandelion is removed from the garden not because of aesthetic reasons, but because of the species’ reputation as a heavy seed producer and ability to quickly establish a monoculture that may out-complete more desirable ornamental plants. Lurie Garden appreciates the ecological value of dandelion as a source of pollen for foraging pollinators, but in the specific setting of Lurie Garden, where a particular design is to be maintained, the plant is considered weed species to be controlled.
Plants that Have Become Difficult to Control
This category of weed at Lurie Garden is comprised of plants most gardeners may not consider as traditional weeds. Many of the plants in the group are perennial plants once installed as part of the garden’s design, but have become too aggressive or ‘weedy’ in the garden and must now be removed. Often they are beautiful plants, but act like real bullies in the garden.
Tradescantia (spiderwort) is a New World genus of plants in the Commelinaceae family, with many species native to North America and several cultivars available in the horticultural market. Tradescantia was planted in Lurie Garden as part of the original design plan with hopes plants would naturalize to fill-in bare soil areas. It accomplished this task well – in fact, the plant grew too well in the garden’s setting and began to out-complete surrounding plants. The designers and horticultural staff, using the garden’s ecological approach to management as a guideline, made the decision that Tradescantia must be removed from the garden’s plantings. While large areas of the garden have been cleared of this ornamental species, due to the plants ability to seed-into areas and reproduce by underground rhizomes, plants continue to appear throughout the garden – If any part of the root is not removed, a new plant can grow from the remnants. Each new appearance must be hand-dug to prevent a future appearance.
Plants We Leave or Use in the Garden
Lurie Garden’s ecologically-informed approach to garden management means that, for some weed species, the time, effort, and soil disturbance required for removal outweighs any damage the weed plants themselves cause in the garden. In fact, many of the weed species in this category may serve beneficial purposes in the garden—attracting local pollinators to the garden or serving as groundcover plants to fill bare soil and prevent more aggressive weeds from establishing.
Oxalis stricta (yellow woodsorrel) is a native North American plant in the Oxalidaceae family. Despite being one of the most ubiquitous weeds in garden and greenhouse settings, several interesting ornamental cultivars of yellow woodsorrel have been developed. At Lurie Garden, yellow woodsorrel is one of the most common weeds encountered throughout the perennial planting beds. Additionally some gardeners may learn to appreciate their lemony-flavored seed capsules as a garnish, making them a very welcome edible weed.
Lurie Garden staff and volunteers rarely bother removing yellow woodsorrel from the garden. This weed species is not only somewhat attractive, but also serves as a worthwhile groundcover to fill bare soil spots that would otherwise become infested with more aggressive weed species. Oxalis stricta is often found growing in combination with Duchesnea indica (mock strawberry), the latter being another common weed species left in the garden to serve as a groundcover.
In the early spring, Lurie Garden’s perennial planting beds are often covered with Cardamine hirsuta (bittercress). This annual or biennial member Brassicaceae can be one of the first plants blooming at the garden. We do not remove bittercress due to its prevalence throughout the garden, small size, and pleasant early spring flower. Additionally, this weed species is quickly shaded out by other ornamental perennial plants as the spring growing season progresses.
Plants that Disturb the Design of the Garden
There are some plants that just find themselves growing in the wrong place – Asclepias syriaca (common milkweed) growing in the middle of our iconic Salvia River, for example. In these cases, garden horticulturalists make the decision to remove the ‘weed’ even though the offending plant is actually an ornamental perennial elsewhere in the garden’s design. In the case of plants critical to life-cycles of insects or other animals, out-of-place plants are removed before being used for egg laying or other important life-cycle stages.
Weed Control at Lurie Garden
How best to control weeds in gardens and lawns is an often hotly debated topic. Each gardener has their preferred weed control method and tool. Weed control does not have a one-size-fits-all solution. Much as the gardener must consider the location, invasive potential, ecological function, and design consideration of a weed to determine if it should be removed; before implementing a weed control method, gardeners must consider personal or professional philosophies and the ecological impact of their preferred control methods.
Lurie Garden uses sustainable and ecologically-informed methods of garden management that attempt to balance the aesthetic requirements of maintaining the artistry of the garden, while simultaneously relying on the resiliency and plasticity of the garden and its biodiversity as an ecosystem.
For weed control, applying this sustainable philosophy means that no synthetic herbicides are used within the garden and alternative methods are used, evaluated, and applied throughout the garden setting. Methods of weed control at Lurie Garden include:
- Hand pulling and digging – Used for most weed species found in the perennial planting areas of the garden.
- Burning – Weeds occurring in the cracks and crevices of the public pathways throughout the garden are burned using a hand-held propane torch.
- Shading – Many early spring weeds occurring in the garden are not pulled or hand-dug because the surrounding perennial plants will, later in the growing season, grow taller than the weed plants, shading them out of the garden.
- Ignoring – Many weed species are simply ignored because they fill bare soil spots throughout the garden and help prevent more aggressive weeds from becoming established.
Quick Tips – Deciding What Weeds to Control
- Learn about the specific plants that start voluntarily growing in your garden. You may learn that the ‘weed’ you have been pulling for many years may actually be beneficial.
- Consider the location, potential function, and invasive potential of a weed before controlling.
- Be proactive, persistent, and thorough in controlling aggressive, invasive, and noxious weeds in your garden.
- Research new plants before installing in your garden. Some ornamental plants may become weeds in your garden setting.
- Weed control is not a one-size fits all scenario. Consider multiple methods of weed control for maximum effectiveness. Aim to work smart not hard.
- Be open to volunteer design surprises. If a controllable plant suddenly appears in an unplanned place, wait to see if it creates a new, desirable effect that you would not have thought of otherwise. You can always remove the plant later.
- ‘Weeds’ can surprise you! Take some time to examine the plant you are about to eliminate. A weed may have an interesting or beautiful character that brings a welcome, unique addition to your garden.
Do you have any stories of an ornamental plant turning hostile in your garden – or any ‘weeds’ you have started to tolerate or allow?
Weed Identification Resources
Two favorite weed identification and control guides for Lurie Garden staff and volunteers are:
- Alexander Martin. 1987. Weeds. St. Martin’s Press – This small format book (only 6 in. x 4 in.) is a good quick-reference guide for the most common weeds found in North America.
- Sally Roth. 2002. Weeds: Friend of foe? The Reader’s Digest Association – This book is both a good identification guide and unique coffee table book to stimulate discussions with gardener and non-gardeners alike.
Fascinating treatment of a perennial issue, this piece results in a more informed relationship with plants out of place. Photos are fantastic with clear caption material.
Please continue to publish Lurie Gardens’ considerations. How about a primer on soil? Seasonal practices? A focus on your volunteer corps?
Thank you for this thorough write up on weeds.
Thank you for the great comment and suggestions for future blog topics, Don. Stay tuned for more on soils, garden management, and design from a Lurie Garden perspective.
I have two problem inhabitants in my garden: rabbits and “creeping Charlie” – I remove as much as possible “Charlie” from around plants, so they don’t smother everything and leave the rest as groundcover and I cage newer plants to discourage rodents – I still need the “bunnies” hopping about, after all it’s a wildlife garden
Fred: Sounds as if you’ve got your hands full in the garden!
As for your rabbits, caging new plants and/or a perimeter fence around your most critical garden areas is a great choice. Exclusion is not a cure-all, as it must be used annually and those plant-munching critters will sometimes find their way around your fencing.
Now, for your creeping Charlie issue. First, verify you indeed are dealing with Clechoma hederacea (creeping Charlie or ground ivy). Once you have confirmed the plant’s identify, you can select the best course of treatment. For creeping Charlie, increasing light levels and reducing soil moisture are the best two treatments. Clechoma hederacea grows best in shade and moist soils, so if you can prune surrounding plants to increase light levels and allow the soil to dry more rapidly this will, over several seasons, slow the aggressiveness and limit the spread of creeping Charlie. Do not pull, cut, or use a hoe to remove the plant as multiple new stems will regenerate from broken underground stems.
Best of luck!
Wonderful! I learned this lesson the hard way by ignorantly pulling all the jewel weed from our drainage ditch (in the country in upstate NY), which was swiftly replaced by much eviler stuff. So sad. We developed a similar weed guide of sorts for the 62nd St Community Garden (62garden.com) so our gardeners could learn about the worst ones like bindweed and not waste time on plantain. Thanks. I’ll share this.
Learning from mistakes with a dash of trial-and-error…these are what makes gardening such fun!
Plants are healthy
Had this misfortune of getting bindweed in a stacked stone raised bed. Fought the good fight with it for six years using solaization and digging. I managed to slow it down but not kill it off. Wiped out a tardiva that was too small to fight it off. Finally gave up and took bed apart and sifted it to pull out all of the roots that could be found. This year I still have some plants coming in from seed but much as I hate to, I’ve been using an herbicide just on that plant to knock it down then dig it out. Now using layers of paper and mulch to keep it down. The adjacent bed was also sifted but for this one I waited until late in season to see what was present after sifting roots from soil. This bed I used and old trick from my TN Southern childhood. I used old wool carpets as a weed block in this raised bed and covered the carpet with stone. Instead of a planting this will be a hard scaled area. I know my limits and fighting bindweed is a tough one.
Sounds as if you continue to fight the good fight, Jo. Bindweed is tough, but sounds as if you have made good progress in knocking the weed back. Sometimes all gardeners can hope for is to knock back a weed, like bindweed, to a tolerable/manageable level.
Herb Robert geranium is one plant that although love it, Stinky Bob does have a tendency to be a bit prolific. However, it is relatively easy to pull out so its more of a nuisance if caught before flowering begins.
Corydalis lutea also spreads quite a bit in my garden but I welcome every plant and I’m often surprised by where they appear.
Columbine (Aquilegia so) . I have several that were present when I purchased my home and have added throughout the years. It appears that each year’s seedling are different from their parents. I have had some pretty wonderful surprises and welcome them all.
Echinacea seems to be very prolific in my yard but I’m happy to just dig the seedling and share as I like to leave the seed heads on for the birds over the winter.
My hosta tend to be prolific as well but I also count those as happy accidents and just move them to different areas of my yard and use as filler in areas not seen by neighbors but “need” to be planted.
Happy accidents are often some of the best weeds to have in a garden! Thanks for sharing your experiences.
A very interesting article! I was particularly surprised that you allow yellow woodsorrel to stay—but your explanation about it blocking out more noxious weeds has me convinced that I should be allowing most of those dainty, tasty plants in my garden.
I’m surprised that one commenter is allowing creeping charlie in his garden. I’ve read articles and posts about this ground cover, and would not wish it on anyone. Something gardeners don’t realize is that invasive plants spread beyond one’s own garden. If your neighbor loves creeping charlie, chameleon plant, violets, Grandpa Ott morning glory, or porcelain berry vine, chances are you’ll be playing host to those invasives whether or not you want to. These are all attractive plants (particularly the porcelain berry vine) but I would advise others to stay away from them.
I used to get so excited about the “hardy” plants that can grow “just about anywhere.” After spending many hours and seasons tearing out and hunting down the seedlings of these “miracle plants,” I swore that before getting another plant I would first check online (invasive.org and the Illinois DNR) to make sure it’s not on their list.
One more warning: Birds eat berries and seeds and distribute them all over the place, not just in the immediate vicinity.
That said, thank you for publishing this article. It really made me think about those weeds that are OK to keep!
I landscaped my yard with all midwestern native prairie plants beginning in 1998. Some things worked, while some others didn’t. I found many plants that I planted. that while controlled by competition in the prairie, ran amok in my gardens, Spiderwort being among them. Others are members of the Silphium genus, in particular, Cup Plant and Rosin Weed. Then there is Joe Pye Weed, essential to any savanna garden, but it is unbelievably aggressive wherever it lands, as is its perfect companion, any of the Woodland Sunflowers. One more, that only became aggressive after a particuraly rainy spring is Virginia Waterleaf. It completely destroyed a couple spring ephemeral gardens.
As a Newbie, I am always searching online for articles that can help me.
Great article about weedy design considerations at the Lurie Garden, I have had a similar fight with Aegopodium podagraria both green and variegated versions that the previous owners thought would be wonderfull in the woods and open fields. It has involved carefully hand digging and re-digging, but also in some areas unfortunately spraying ( my least Favourite option) . Wonderfull work you do, love the articles from a zone 4 gardener
This is my second summer attempting to garden, and we have a ton of oxalis/woodsorrel in our flower beds. But it’s pretty! And provides coverage! My wife disagrees thoroughly. Thank you for your helpful article, which may save our woodsorrel from being plucked.
This is so great! I think, depending on her tastes, she may want to keep it for another reason….Mature wood sorrel seed pods have a delicious lemony flavor. I learned this when I was at a restaurant and was served fish with them sprinkled on top. I was so delighted! (Of course, make sure you check that what you’re eating is safe to eat!!) Here is a video that may be helpful: https://www.youtube.com/watch?v=ANjrngwLOVE