Cheyenne Garden Gossip

Gardening on the high plains of southeastern Wyoming

Match wits with weeds

Tyler with stirrup hoe

Tyler Mason, Cheyenne Botanic Gardens’ horticulturist, demonstrates use of the stirrup hoe in his wide beds in his plot at the community gardens. Photo by Barb Gorges.

Published July 12, 2015 in the Wyoming Tribune Eagle’s Journey section: “Can you weed out the weeds? Try these strategies to get your lawn and garden in tip-top shape.

By Barb Gorges

“A year of weeds leads to seven years of hoeing.” –Folk saying recounted in “Sustainable Horticulture for Wyoming,” University of Wyoming Cooperative Extension Service.

The penstemon in my perennial flower garden is creeping into the lawn. The grass is creeping into the flowers. Technically, that means both penstemon and grass are weeds—out-of-place plants.

Besides growing where they are unwanted, most weeds are aggressive, crowding out preferred plants and even reducing the productivity of vegetables. Often native to Europe or Asia, coming here accidentally or intentionally, they seem to outpace even native plants, excelling where ground is disturbed.

Unfortunately, weeds aren’t usually as edible as our vegetables or as beautiful as our flowers. But for a different outlook, check out “The Wild Wisdom of Weeds” by Katrina Blair, a Colorado gardener.

I recently visited with Tyler Mason about strategies for dealing with weeds. He is now the Cheyenne Botanic Gardens’ horticulturist. He practices integrated pest management, opting for the least toxic, but effective, methods to control weeds.

Thistle

Canada thistle may require several applications of appropriate herbicide to eradicate it. If you chose not to poison it, don’t let it flower and spread seeds. Photo by Barb Gorges.

Know your adversaries

The two biggest weed pests in gardens here are field bindweed and Canada thistle. Both develop extensive roots. And any tactic that doesn’t remove or kill every little piece will increase their vigor.

Creeping bellflower (Campanula rapunculoides), with stalks of multiple lavender bell-shaped flowers, runs a close third because it spreads too well.

Also on Tyler’s list: dandelion, curly dock, crabgrass, plantain, and common groundsel.

The book “Weeds of the West” is a great field guide to weeds in gardens, cropland and rangeland.

Beware of Trojan horses

Manure is great fertilizer, Tyler said, but not if it still has viable seeds when not thoroughly composted. Sometimes, weed seeds may come with plants you bring home.

Plantain

Plantain, native to Europe, is a shallow-rooted weed that likes bare, compacted soil, thus its nickname: “white man’s footprint.” One plant can produce 20,000 seeds. Photo by Barb Gorges.

Don’t stir things up

There are hundreds of seeds lying dormant in the soil just waiting for a bit of sunlight. Tilling the vegetable patch brings them to the surface.

No-till gardening is becoming more popular. Once a bed is built, the soil and its micro-organisms are allowed to do their thing, improving soil structure and fertility. Amendments are added as top-dressing.

In the Botanic Gardens’ community garden Tyler is using wide-bed gardening in his plot this year instead of the traditional rows. Each bed is a berm about 6 inches high by 2 to 3 feet across, running the length of his garden. Access paths on either side are well-mulched with straw, reducing the area needing to be weeded.

By not stepping on the berm and compressing it, the soil holds more water.

“Be effective with your water,” Tyler said. Water right where you need it. Same with fertilizer–don’t broadcast it over the garden, otherwise the excess will feed the weeds.

Stirrup hoe

The stirrup hoe, pushed or dragged so that its sharp lower edge is barely under the soil surface, severs weed seedling roots. Because it disturbs so little soil, fewer new weeds will follow. Photo by Barb Gorges.

Get them early

If your garden has any bare soil, you are bound to see weed seedlings. Pull them right away. Even thistle and bindweed are easy to pull, roots and all, when they are less than 2 inches tall. To disrupt seedlings while you are in a standing position, use a stirrup hoe like Tyler does, pulling it through the top quarter-inch of soil to severe the roots.

How do you know which is a weed seedling and which is a vegetable seedling? Plant seeds in a pattern. Or give your garden an advantage over weeds by transplanting starts rather than direct seeding.

Keep them in the dark

Black plastic sheeting, with holes cut for inserting vegetables, is a way to mulch. Used with drip irrigation and soluble fertilizers, it can be pricey.

Weed barrier cloth is often used for landscape plantings. But it can make it harder for the roots of desired plants to get water and nutrients. Over time, dirt blows in on top and weeds sprout anyway.

Rock mulch is popular these days, but it doesn’t contribute nutrients the way a mulch of organic materials can, like bark.

Creeping bellflower

In Cheyenne, creeping bellflower is quickly taking on a reputation similar to bindweed. It spreads and is difficult to eradicate. Photo by Barb Gorges.

In flower and veggie gardens, Tyler recommends materials that compost quickly and can be turned under, like grass clippings, tree leaves, straw (not hay with seeds). Take care they are not from diseased plants. Also, make sure they were not sprayed recently with herbicides. Weeds that poke through are easier to pull because the soil surface has not been baked by the sun.

Another way to keep weed seeds in the dark is to grow more densely—keep the ground shaded. Maintaining a healthy lawn cut about 3 inches high will shade out weeds, Tyler said.

Behead them

It is amazing how many seeds one weed can produce. The master gardener manual says dandelions have 15,000 seeds per plant.

Don’t let weeds flower. If you don’t have time to remove them, deadhead them by hand or mower.

Hori hori knife

The hori hori knife, a Japanese garden tool readily available here, is good for removing bigger weeds. It has a sharp edge on one side and a serrated edge on the other. Photo by Barb Gorges.

Dig them out

Tyler is fond of the hori hori knife, a traditional Japanese garden tool that looks like a narrow, pointed hand trowel with a sawtooth edge on one side. This is a good tool for weeds that breach the mulch, are too big for the stirrup hoe, or that have roots about as deep as the hori hori is long.

Overgraze them

When I was a range management student, I learned that cattle prefer forbs (wildflowers) over grass. They will nibble these “ice cream plants” to death if left in a pasture too long. Conversely, they could be trained to eat weeds.

So if you have thistle and bindweed in your garden, keep removing the green leafy parts as often as you can and eventually the plants can very well starve to death. At least they won’t spread.

If you have an over-grazed pasture full of weeds, please consult the Laramie County Conservation District.

Bindweed

One of the most difficult weeds to kill, field bindweed grows bigger leaves in more fertile soil. Tyler Mason likes to isolate bindweed from non-target plants by coiling up the vines in a cup with a hole in the bottom, and then spraying it with an appropriate herbicide. Photo by Barb Gorges.

Poison the invincible

There might be a situation that justifies using herbicides. But first, you have to find the right one for your weed, so you must be able to identify it.

Then you must follow the directions exactly as to formula strength, timing and weather conditions. Keep in mind that some herbicides will volatize—turn to toxic gases—when temperatures are more than 85 degrees F and then will blow onto non-target plants, the neighbors, your pets or yourself, Tyler said. He doesn’t recommend broadcast spraying or using feed and weed products. It can lead to toxic runoff which pollutes surface and ground water. Spot treat instead.

Exceeding herbicide label recommendations is another problem. It can burn the top of the plant, not allowing the plant to transfer the toxin to its roots—and so it re-sprouts instead of dying.

Finally, be sure to deadhead weeds before spraying so that bees and butterflies won’t be poisoned by poisoned flowers, Tyler said.

Draw the line

I heard that a concrete curb poured around the edge of a flower bed can be breached by grass.

I’m trying this solution, edging a bed with flagstones flush with the lawn. The lawnmower can run two wheels along them and no string trimming is necessary. However, in the spring, or whenever grass shows up between the stones, I can upend them and take a shovel to the white root-like grass stems, known as stolons, and cut them back.

Another advantage over concrete curbing: I can change the size and shape of my flower beds whenever I like.

Gardening is about discrimination, discouraging some plants and favoring others. Vigilance is important. But is there a gardener who doesn’t enjoy an excuse to spend time out in the garden?

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