weeds

Ragweed and Goldenrod: Weeds to Watch This Week

August 22, 2018

(Above, a Canada goldenrod invasion)

We’ve been doing raingarden maintenance lately. This includes pulling a lot of ragweed and Canada goldenrod. Read on for more about these invasives.

Ragweed, Ambrosia

Recently I took a few minutes to watch the late evening news. I was excited to see a segment on ragweed. This is the culprit behind the hay fever symptoms suffered by as much as 20 percent of the population. A doctor in a white coat discussed actions to help alleviate symptoms, including drugs, avoiding the outdoors and keeping windows closed. He might have mentioned getting to the “root” of the problem by addressing the plant itself.

The segment mentioned finding ragweed in ditches and along stream banks, though viewers never actually saw what ragweed looks like. But our Conservation Corps crew members know! We had spent a good part of the day pulling or trimming both common ragweed (Ambrosia artemisiifolia) and giant ragweed (Ambrosia trifida) from raingardens at some Minneapolis schools. With their distinctive foliage, both species are easily identified.

The best time to pull common or giant ragweed is during the spring as the first leaves appear. As they mature, their roots become harder to pull from the ground. This late in the season, ragweed can be trimmed with loppers or hedge shears. Because they are annuals, they should not re-sprout, though if the heat continues we might see shoots growing from the cut stems.

Canada goldenrod, Solidago canadensis

Goldenrod is yet another weed we have come to know all too well in recent weeks. Interestingly, many people unfairly blame goldenrod for the allergy symptoms caused by ragweed. In fact, all species of goldenrod (genus Solidago) have pollen grains that are far too large to impact human sinuses and so should remain blameless.

Canada goldenrod: These specimens are 4’ to 5’ tall.

In your yard, you may find yourself less sympathetic to one particularly aggressive species of this perennial, Solidago canadensis, commonly called Canada goldenrod. It can quickly grow from a tiny seed that blew into your garden into an invasive, overwhelming mass up to six feet tall in damp, lush raingardens. Pulling it will slow it down, but the best method is to cut it before any flowers mature. You may leave the cut stems to re-sprout. New shoots that emerge in the next couple of weeks are far more sensitive to herbicide or a 20% acetic acid solution.

Canada goldenrod: Long, fleshy roots send up other plants around the “mother” plant that blew in as a seed.

Gardening tip

If using a spraying wand on the new shoots, try this trick to protect surrounding plants: attach a large funnel over the sprayer nozzle and tape it in place. Load the sprayer with the 20 percent acetic acid solution. As you walk, place the cone of the funnel over individual plants, giving each a quick squirt, and then move on to the next plant. This should prevent harming desirable native species mixed in with this garden aggressor.

– Douglas Owens-Pike, Metro Blooms Sustainable Landcare Expert, douglas@metroblooms.org

Weeds to Watch This Week

July 11, 2018

Weeds, a.k.a. Wild Urban Plants

What is a weed? Emerson said they are plants whose utility has yet to be found. From an ecological perspective, they are colonizers of disturbed soil. Often annual, they produce impressive amounts of seed that float off to find bare soil, sites free from competing plants. They are modifiers. Weeds build soil organic matter to make it easier for perennials to follow in subsequent seasons. Perhaps we could change our focus to understanding their utility – thinking of them as “wild urban plants” as defined by Peter Del Tredici in his book, Wild Urban Plants of the Northeast, Cornell University, 2010.

This week we have many possible candidates that should be controlled before going to seed. This discussion will focus on principles of disturbance and where to focus attention using a few examples.

This first view is the gravel between and adjacent to an actively used path at a driveway gate:

We can identify a number of wild plants. Let’s look closer to see which ones we should invest time in controlling.

The dominant plant in this view below, with small, opposite leaflets and a reddish, multi-branched stem that stays tight to the ground, as implied by its common name, prostrate knotweed, Polygonum aviculare, could be a keeper. It is extremely tough, adapted to drought, compaction/foot traffic, salt tolerant, and never needs mowing, and converts bare soil or gravel into a soft carpet. Why fight it? Here, it would be best to select out the grass seedlings (either smooth crabgrass or purple lovegrass) before they get large.

In the cover photo at top, we have at least six species growing in a 6” x ½” gap between flagstone. Here it is again, plants numbered:

From left to right:

prostrate knotweed again
taller lance-leaved, could be horseweed or marestail, Conyza canadensis (pull that now, before it gets to 6’ maximum height). More information coming in a future post.
scalloped, single leaf (buttercup or creeping Charlie?), wait to ID before pulling
sprawling stem, leaflets like clover, tiny globular cluster of yellow flowers is black medic, Medicago lupulina. Why bother controlling this tough plant? It stays tight to the ground, has pollen for bees, fixes nitrogen to build soil nutrients with Rhizobium It is extremely drought tolerant and grows in the worst conditions in full sun.
fine leaflets on green stalk (just two plants), partridge pea, Chamaecrista fasciculate. Wonderful native annual, probably too tall for this location. More to follow below.
Broadest leaf on far right, broadleaf plantain, Plantago major, nice prostrate leaves, but without sufficient trampling would get too tall in this path setting. More to follow.

Several partridge pea plants (raspberry at bottom of view should be pulled now) next to gate post:

In this location their standard 12-18” height would not be a problem. Great bee attractor; long-tongued bees pollinate large yellow blossoms with clusters of dark stamen. This native can colonize moving sand. Extremely drought tolerant and another nitrogen-fixing root system. Its ripe seeds explode out of the 2” long pods seeking new gravel or empty habitat to exploit the following growing season. Cut it if it is too tall and it will bloom close to the ground.

Another view of broadleaf plantain, an indicator of compacted soil:

Chewed leaves applied on skin make a quick remedy to soothe insect bites or skin rash from stinging nettle. Save this plant whenever you can.

Bottom line: Make the most of the colonizer plants that might otherwise annoy you by understanding their value as ecological healers.

– Douglas Owens-Pike, Metro Blooms Sustainable Landcare Expert

Reed Canary Grass: Weeds to Watch This Week

June 19, 2018

Reed Canary Grass, Phalaris arundinacea

reed canary grass (note mystery invasive in foreground)

This is a plant you want to know to attack quickly if it shows up in your raingarden. I’ve seen it invade dry boulevards where the owner thought it was just a desirable showy grass. This grass is nearly impossible to eradicate in extensive mats. If you see it blooming anywhere, harvest the flowers to prevent seed from maturing. Minnesota DNR classifies it as an ecological threat.

You can kill it with a 20% acetic acid (vinegar) solution. Household products contain <5%. We have not found it locally. Order it online, in one-gallon jugs, and spray at full strength. The dying plants will succumb quickly, but then you need to watch for seedlings. Monitor the area for at least three years. Solarization with a cover of black poly will kill seed on the surface as well as mature plants. This takes a full season of heat and no water. Just be careful to go beyond the existing clump, as it spreads by creeping rhizomes as well as seed.

I plan to experiment with using native prairie cordgrass (Spartina pectinata) to see if it will outcompete reed canary grass, but the native gets 6–10’ tall. Perhaps it can be a privacy hedge if you have the space. The native can also handle heavy flow in bioswales coming from parking lot pavement. Add other tall species to help hold it upright, e.g., big bluestem, gray-headed coneflower, meadow blazing star.

Reed canary grass is easy to see at a glance. Bonus points for anyone who can identify the yellow/green blooming invasive plant in the foreground. Reed canary will get chest- to shoulder-high, even higher with more water available.

The good news is that we can identify it from a distance, and when looking closer see a distinctive diagnostic trait: it has a papery ligule (where the leaf attaches to stalk) that stands up 3 mm or ~ ¼”. This is the only grass with such prominent ligules.

– Douglas Owens-Pike, Metro Blooms Sustainable Landcare Expert

Raingarden Maintenance Made Easier: Good Timing and Tools

June 13, 2018

In a raingarden, there will always be weeding, but you can make it easier on yourself if you have good timing and the right tools.

That was one of the main messages at the first session of Sustainable Landcare: Raingarden Maintenance, a three-part workshop series organized by Metro Blooms’ Blue Thumb organization. The workshop was held at the Shoreview Maintenance Center, where participants started off in the classroom before going outside to a large raingarden, where they weeded. And weeded. A lot.

It was led by Douglas Owens-Pike, Metro Blooms’ sustainable landcare expert, who showed that the best tool for creeping thistle can be a simple pair of scissors that you use to cut away the green as it emerges. Or that a pair of channel lock pliers, often used in plumbing, makes getting the roots out much easier when pulling tree seedlings.

But the main focus was the hands-on work outside where, almost immediately, Owens-Pike demonstrated the channel lock pliers’ efficacy by pulling out a very long-rooted Siberian elm seedling, and holding it aloft victoriously. There were a lot of tools available for participants to try as they weeded. Owens-Pike identified different plants and gave tips on how to deal with them.

Participants also shared knowledge and experience from their own experience. Kathy Jantzen had a raingarden installed by Metro Blooms four years ago to divert runoff from her garage and driveway. “By July, we’re overwhelmed,” she said. “We can’t get in.” She took the workshop to help solve this problem.

This series is sponsored by Rice Creek Watershed District, the cities of Shoreview and Fridley, and the Coon Creek Watershed District. The workshops are scheduled at different times in the growing season.

— Aleli Balagtas, Metro Blooms Reporter

Curly Leaf Dock: Weeds to Watch This Week

June 11, 2018

Curly Leaf Dock, Rumex crispus

This ubiquitous plant is one you want to get to know. Here is a view of a patch on a boulevard, with seed beginning to ripen. If you catch it early enough– plants with sufficient moisture supply and leaves recently unfurled–you can eat it! With our recent rain I have found it quite satisfying to pull, even without disturbing the soil. The trick is to grasp the stalk at ground or slightly below, with a steady, firm pressure as you pull. Ah, when that full 12” or longer root stalk pulls free from your soil, you can smile and whoop “Wahoo!” As this first set of views show, if you don’t catch it before the seed is distributed, you are in for a long battle over several years of pulling seedlings. It can be found in the most mature natural plantings, as its seeds drift down and find the smallest amount of bare soil. Never give up looking for this invader. Let me know what you think of the taste. For more details go to our local author, Samuel Thayer’s Nature’s Garden : A Guide to Identifying, Harvesting, and Preparing Edible Wild Plants, Forager’s Harvest, March 2010.

NOTE: The channel lock pliers, mentioned in a previous post, will facilitate your ease of pulling, especially when dealing with a larger population.

– Douglas Owens-Pike, Metro Blooms Sustainable Landcare Expert

Creeping Charlie: Weeds to Watch This Week

June 1, 2018

Creeping Charlie, Glechoma hederacea

If you have not encountered this plant in your travels or heard a discussion about what to do with this aggressive non-native ground cover, you probably need to get out more. It seems to be everywhere. While it can be a daunting process, it is possible to weed it out. Of course this is easiest if the invasion is just getting started. A well-established population will have an accumulation of seed in the soil such that even if you were to douse the area with herbicide it will be right back, again and again, from viable seed.

It is a bit tricky to weed out the root without just breaking off the shoot. If your efforts are limited to breaking off the above ground parts you will have a never-ending task. Ideally, begin the weeding after a gentle, soaking rain. Use a hand fork to loosen soil and gently tug to pull as much of the root system as possible.

Creeping Charlie in shade — Setting of dappled shade, with ash tree seedling and violets, mixed with nearly solid cover of creeping Charlie. This is an area where effort has been made to control common buckthorn.

Any spot treatment with herbicide should be followed with replanting desired native diversity to quickly cover the ground left bare.

While this non-native flower does provide nectar and pollen for a variety of native insects, studies have found it requires seven times the number of flower visits to obtain the same nutritional value as provided by local native plants. Here are some suggested replacements (arranged from shortest to tallest): golden groundsel, hepatica, wild ginger, dwarf-crested iris, Virginia waterleaf, wild geranium, white woodland aster, big-leaved aster, heart-leaved aster, zig zag goldenrod, and columbine. While mature size of plants varies with how much light and water is available, you can maintain a groundcover appearance by monthly trimming what would be much taller plants. Following this prescription, white woodland aster will bloom at six inches tall, in fall, still providing food to pollinators.

Identification: creeping Charlie is a mint, so its stem is square, and is fragrant when crushed. While it generally stays close to the ground, it can climb up larger plants with a stout stem and eventually smother them by blocking most available sunlight. Generally prefers shade, but will persist in the sun if spreading from a well established shady area. Flower is a deep blue, deep tube, with leaves distinctively scalloped , and displaying prominent veins.

NOTE: can be toxic to horses when consumed in large quantities.

– Douglas Owens-Pike, Metro Blooms Sustainable Landcare Expert

Garlic Mustard: Weeds to Watch This Week

May 29, 2018

Garlic Mustard, Alliaria petiolata

If you have ventured out walking the woods this week, you may have noticed clusters of small white flowers on stalks about knee high with triangular shaped leaves with large toothed margins. This plant is likely garlic mustard. There are no other white blooms that look similar at the point in our spring. The many native species currently blooming white all have large petals.

Here are a couple photos from MN DNR:

This is the right time to be pulling this extremely aggressive invader. If you can catch them in bloom you can interrupt the plant’s two-year life cycle. If their seed pods have started to form you will need to bag them for disposal. CAUTION: in wet weather, they can keep blooming even after being pulled from the earth!

If you miss this opportunity, seed pods burst to release thousands of seeds for every plant. Then you will have the chore of working for seven years to exhaust this one year’s seed production. While it is possible to kill the first year rosettes, it is easiest to pull the whole plant out of the ground as it comes into bloom. You don’t have to bend over as far and it pulls out easier than first-year plants. Why is it important to get rid of this menace? It has a chemical in its roots that inhibit mycorrhizal fungi that are essential for the health of full-grown trees that depend on a collaboration underground to extend the root system of the tree using the fungal mat. The fungi benefit from sugars that the tree supplies. Imagine a mature tree being killed by this knee-high biennial.

If you notice the plant and it is not on your property, please inform the owner that they are harboring a noxious plant. If that owner is not willing to address the problem ask for their permission to pull any plants you can find. Put them in standard paper yard waste bags and leave for your city to collect. Do not attempt to compost on your own unless you know you are achieving high temperatures in your compost heap. In my own yard, in South Minneapolis, garlic mustard showed up under our lilac at the corner of our lot next to the public walk. I assume the seed fell off someone’s shoe or a dog’s fur.

Edibility: some find the taste of the leaves to make a palatable salsa or pesto. Others find it not so great.

– Douglas Owens-Pike, Metro Blooms Sustainable Landcare Expert

Tree Seedlings: Weeds to Watch This Week

May 8, 2018

Tree seedlings are easy to spot right now:

Any woody plant with foliage emerging in a garden is probably not wanted, but very easy to pull. Get them while they are less than 6 inches tall and they can be pulled by hand.

If they get any larger, use a channel lock pliers, to pull gently but firmly without cutting it off. I’ve successfully pulled hackberry seedlings that had 3′ of root without digging, by just gently pulling the base of the tree with that pliers. Nice long, padded handle. Can purchase in a variety of sizes that fit your hand.

– Douglas Owens-Pike, Metro Blooms Sustainable Landcare Expert

Metro Blooms’ Maintenance Training Pilot Program

February 27, 2018

Anna, landscape designer, gathers Wilderness Inquiry youth to talk about the day's maintenance tasks. — Anna, right, leads Wilderness Inquiry youth in the day’s maintenance tasks.

The Sustainable Need to Weed

“How many of you, if we go out to weed right now, would know what you’re doing?” Anna Bierbauer, our Metro Blooms landscape designer, asks. In a classroom at Folwell School this summer, two Wilderness Inquiry youth raise their hands.

Soon after a short lecture about two species of weeds, the crown vetch and spotted knapweed, as well as the correct way to pull and dispose of those weeds in order to not spread seeds, the group of ten heads outside to the school’s large raingarden.

They pull on some gardening gloves, breathe in the humid, rainy air, and begin working on one of the largest weeding and maintenance jobs Metro Blooms has seen for a raingarden in south Minneapolis.

For many property owners, this would probably be a familiar feeling. Most people maintain their own gardens in those rare occasions after work or on the weekend, grudgingly.

Anna talks more about the overall problem she’s seen out in the field. “In the last 10 years, the use of green infrastructure in stormwater management has increased greatly including small residential rain gardens designed by Metro Blooms,” she says. “But, the maintenance of said infrastructure has not increased at the same rate, largely because these rain gardens or swales or bioretention ponds require a certain set of skills, and there aren’t enough trained laborers.”

And the problem’s impact appears to be deeper. “In general, most people don’t realize the impact a lack of maintenance will have on functionality or will wait until the garden looks bad to address maintenance. If an inlet is clogged, short-rooted weeds have overrun the garden, or the outlet is plugged, the garden won’t work as intended. The main issue for raingardens or vegetated BMPs is that if the plants aren’t healthy, the BMP isn’t functioning or doing its best at filtering or infiltrating stormwater,” Anna says.

Wilderness Inquiry staff, left, help youth identify and pull weeds properly after Anna's training. — Wilderness Inquiry staff, left, help youth identify and pull weeds properly after Anna’s training.

After hours in the raingarden, Wilderness Inquiry youth pulled enough crown vetch and spotted knapweed to fill more than five waist-high brown bags, and we have to keep in mind that only two weed species out of many were pulled from the area.

To address the issue of maintenance, Metro Blooms put together a maintenance training pilot program, empowering youth in Minneapolis with skills and in-depth knowledge about the sustainable landcare field in a practical, hands-on way. The pilot program was funded by Hennepin County Green Partners program and the Minnehaha Creek Watershed District and teaches skills that many raingarden owners, caretakers, and businesses need.

“After discussing the curriculum with several professionals, we decided to focus on maintaining vegetation, identifying weeds and desirables, removing weeds, and inspecting sites. Over the course of the summer, we added in smaller structural pieces such as permeable pavers, trench drains, and catch basins to broaden the experience,” Anna says.

Metro Blooms completed similar work with Mississippi River Green Team, featured on Kare 11. Each student, each person, walked away from the program with knowledge and an education in a rising, necessary need: maintenance for green infrastructure in stormwater management.

Metro Blooms landscape designers Anna, left, and Lacey, right, discuss the future of the Folwell School's raingarden and maintenance plan. — Metro Blooms landscape designers Anna, left, and Lacey, right, discuss the future of the Folwell School’s raingarden and maintenance plan.

Although these students and youth may move toward other pursuits than sustainable landcare, the maintenance pilot program has revealed an opportunity in the field at large: providing maintenance services and education for property owners with raingardens and BMPs.

…..

Selina Scheumann holds an MFA in creative writing and was the Communications Intern at Metro Blooms.

Warm Season Weeding

August 6, 2013

Weeds. They can be daunting at times, especially when you’re looking at your garden or yard thinking, these can’t ALL be weeds, can they?! Weeds can be tricky to identify, so the first step is knowing what those common weeds look like. Generally, weeds are split into two categories: cool season weeds, and warm season weeds. We’re well into the warm season now, so I’ll cover the common ‘warm season’ weeds below. However, if you want to know more about cool-season weeds, check out our blog post on that.

In general, our recommended weed-elimination method is hand pulling. I know, it can be a lot of work, but it’s also an excuse to spend nice summer evenings outside creating a beautiful garden without the use of chemicals.

Quackgrass: Hard to eliminate perennial grass. Be careful not to break the rhizomes when you dig it up, or you’ll have hundreds of new shoots.

Crab Grass: Spreads by seed with a high germination rate.

Garlic Mustard: A prohibited noxious weed that should be controlled by pulling.

Barnyard Grass: A vigorous competitor for space and nutrients, you should hoe young plants before they form seeds.

Common Ragweed: Best to hoe or hand-weed young plants.

Creeping Charlie: Pull early or use a dethatching rake.

Foxtail: Pull these before your dogs get to them. Dry plant heads often wind up stuck to pets’ skin.

Reed Canary Grass: Typically grows in wetlands but can pop up in wet areas of gardens as well.

Volunteer Trees: These are often the most prevalent weeds in a garden, especially if you have a nearby tree! If you’re not up for removing the seeds when they first fall, you may have quite a few volunteer trees to pull throughout the summer.

Ash Seedling

Maple Seedling

Elm Seedling

Hackberry Seedling

Buckthorn Seedling

Summer Raingarden Maintenance

July 26, 2013

I hope you’ve been enjoying your time in the garden this summer and if you just haven’t had the time to do much maintenance yet (gasp!) it’s about time you get out there! So here are a few tips for you when taking care of your garden for the remainder of the summer. Don’t worry, I’ve got fall tips I’ll share with you later…

Pull Weeds: Pull all warm-season weeds (crab grass, creeping charlie – pictured, foxtail) and volunteer trees (ash, elm, hackberry, boxelder, buckthorn) prior to the Fourth of July (eek, don’t worry you can still pull them now, and should as soon as you see them pop up; besides we all know weeds don’t just stop growing after the 4th of July!). Monitor weed emergence throughout the growing season and pull as necessary.

Inspection: After large rain events, make sure the garden is draining in less than 24 hours. Always inspect for signs of erosion throughout the season. If erosion occurs, re-grade the eroded area and replant with a clump-forming grass or sedge, such as Side-Oats Grama, ‘Karl Forester’ Feather Reed Grass, or Bebb’s Oval Sedge. If the erosion continues, place large cobblestones or boulders in the eroded area. This will minimize the incoming water’s energy. Pay close attention to the side-slops of the garden as these areas are especially susceptible to erosion.

Water: In times of drought, give your garden a drink. This is especially important during the first two years of the garden’s life, when plants are establishing their root systems.

Take Pictures: Please remember to document your garden and its progress. Send us your pictures and we might nominate you for a garden award!

Metro Blooms’ complete raingarden maintenance guide can be accessed on our website and highlights the essential maintenance activities for every season. Remember, if you do the little things now you’ll ensure that you have a beautiful and efficient raingarden for years to come!

Cool Season Weeding

May 14, 2012

As mid-May surprises us with it’s vigor and business, so does the Spring weeds! Here’s some tips and pics for starting the year in control of the gardener’s ancient nemesis. Watch for these weeds popping up uninvited in your garden:

Dandelions: If you can, trowel up the entire taproot. But at least snip the heads while they’re freshly yellow and puffy.

Crab Grass: Rugged and malicious, can stubbornly settle into the driest of soils. (If so, wet the soil and pull as much root as possible)

Clover: Often considered a weed. However depending on aesthetic taste, small white clovers may be desirable in a yard or garden. Sweet Clover is the fast, dominating weed that you should watch out for and control early on.

Sweet Clover (Melilotus officinalis) is a fast colonizer common on construction sites. It can get up to 5′ tall.

Trifolium clovers are considered a weed by some but may also add an aesthetic touch to a yard or garden.

Goatsbeard: The bad kind (Tragopogon dubius) is a nuisance, and a widely dispersed weed. However an entirely different type (Aruncus dioicus) is planted in yards for a shade-tolerant native perennial.

Flowering Aruncus dioicus planted in a yard

Tragopogon dubius – Pull before it flowers!

Creeping Charlie: A merciless ground cover eager to set up shop in your yard.

Thistle: Pull it NOW when it’s thorns are still easy to handle, and before the taproot is too deep in the mid/late summer!

Violets: Pull them early before they’re established in your yard.

Tree Seedlings: Ash, Maple, Elm, and Buckthorn are the most common and can propagate in large numbers up to the hundreds.