Growing Together: Conquering weeds in the yard and garden

Don Kinzler
Forum News Service

Nothing in this world is certain, except death and taxes, according to Benjamin Franklin. That’s not entirely true. He left out weeds.

Anyone with a yard or garden knows that weeds are a near certainty. Plant it, and they will come; weeds, that is.

Weeds can take the fun out of gardening, if we let them get the upper hand in our vegetable gardens, landscapes and flower beds.

But we can win the war on weeds, and the following tips can help.

1. There are no sprays or easy solutions that can single-handedly prevent or remove weeds in our landscapes, perennial flowers and vegetables. Instead, a combination of weed control methods is necessary, plus perseverance.

2. Attack weeds when they’re young. It’s easy to forgo stooping down to pull a tiny weed, but next week, it might be treelike. Trust me, they won’t remain small and innocent if left in place.

3. Know whether the weeds you’re fighting are annuals or perennials. Perennial weeds have underground structures or roots that survive winter, enabling them to thrive from year to year, like thistles, quack grass and dandelions. Annual weeds live for one growing season and die after autumn frost, after dropping seed for the next growing season, like most little weed seedlings that grow in vegetable gardens.

4. Be familiar with the terms “broadleaf weed” versus “grassy weed.” Dandelion, thistle and purslane are broadleaves. Quackgrass, crabgrass and pigeon grass (foxtail) are grassy weeds.

5. Herbicides are products that kill plants. We think of them as weed killers, but if they drift onto or are absorbed by desirable plants, trees or flowers, damage or death are likely.

6. Herbicides fall into three main groups: some kill only broadleaf plants (like 2,4-D as found in Weed B Gon), some kill only grassy plants (like quinclorac and fluazifop) and some kill nearly any plant (like glyphosate, the ingredient in original Roundup).

7. Grassy weeds like quack grass can be eliminated from perennial flowers, asparagus and berry patches with selective grass killers like Ortho’s Grass B Gon and Bonide’s Grass Beater.

8. Weed preventers, such as Preen, are termed pre-emergent herbicides that can be somewhat useful in flower beds and landscapes, killing some annual weed types as they sprout, but not weeds already growing. Other herbicides are termed post-emergent, meaning they’re applied to weeds in active growth.

9. Perennial weeds growing among perennial flowers are a difficult situation, as products like Preen don’t prevent such weeds from growing from established roots. Control by digging, hoeing, pulling, smothering with mulch or precision spot-applying herbicide.

10. Quack grass is a perennial, and there are currently no available selective ways to eliminate this wide-bladed weedy grass from lawns. Crabgrass is an annual that can be eliminated with timely early spring crabgrass pre-emergent products, or with post-emergent crabgrass killers applied when crabgrass seedlings are very tiny.

11. To minimize herbicide use on a lawn, spot-treat individual weeds only, instead of applying chemicals to weed-free lawn sections. If weeds aren’t numerous, digging is often efficient.

12. Most battles in vegetable gardens are with annual weeds. Hoeing, cultivating, hand-pulling and mulching are the preferred weed controls, easiest when the weeds are just emerging from the soil.

13. Don’t let weeds go to seed. One weed can spread thousands of seeds capable of remaining viable in the soil for decades.

14. The most successful month to apply herbicides for controlling perennial-type weeds in lawns and landscapes is September as weeds begin transporting materials downward in preparation for winter. Repeat applications in May and June for hard-to-kill weeds.

15. Successful alternatives to chemical weed control include smothering with mulch-covered fabric, newspaper or cardboard, or hand-digging, pulling, hoeing and cultivating.

Fielding questions

Q: We have a row of evergreen trees that are all either dead or dying, as shown in the photo. What could be the cause, and is there anything that can be done? — Fargo.

A: Determining the cause of tree ailments often requires detective work and looking closely for clues. When trees die, or begin to decline, it’s often assumed they’re being attacked by some disease, for which a spray will bring remedy. Infectious diseases are not the most common causes of tree troubles, though.

In the row of trees in the photo, large old spruce and young small replacements are dead or dying. Although there are several diseases that attack spruce, it would be rare for small young spruce to have “caught” a disease so soon.

Instead, a rapid decline is more likely caused by something in the tree row’s environment. Did lawn herbicides drift onto the trees? Did snow-melting chemicals wash onto the rootzone from the nearby parking lot?

Then I noticed the probable cause. A newer-looking sidewalk runs along one side of the row; a large parking lot on the other. The tree row is located in a grassy strip that is lower than the surroundings. Water from both sides appears to drain toward the low-lying tree row. Spruce can be quickly killed in low areas into which water drains.

The tall old spruce likely achieved much of their growth in decades before the surrounding areas were raised, causing water to drain toward their sensitive rootzone, but once it did, they quickly succumbed. Spruce planted more recently are quickly showing ill effects.

It’s too late to save the tall, older spruce. There’s no way to bring them back. Several of the younger spruce might survive if the grade were changed to improve drainage. In the currant situation, replacing the spruce is futile until the drainage issue is resolved, or moisture-loving species are planted instead.

Q: Last year my lily-of-the-valley had three small, anemic leaf clusters. Now they’re spreading quickly, and I never dreamed they could come up like they did this year. I’ve been digging them out, but I know they will still be popping up. Will Roundup kill the sprouts? Or what else could I use? — Karen, Fargo.

A: Lily-of-the-valley is a pretty perennial that creeps outward from underground “pips.” Its small, bell-shaped white flowers are fragrant, and it grows nicely in the shade. But they are best planted in a spot where total containment is possible, such as the middle of a concrete island, unless you don’t mind them spreading outward with vigor.

They have been known to cross underneath sidewalks, and can certainly pass under most landscape edging. Besides digging, glyphosate (original Roundup) can be applied this time of year to the actively growing leaves, and again in September to sections that resprout. Because they regrow from such a tiny bit of root, persistence over a year or two is usually necessary.

Smothering can also be effective. You can even use cardboard covered with wood chips. The cardboard can be left in place, and will decompose into organic material.

Q: My fernleaf peonies are blooming beautifully, and my neighbor would like a division. When would be the best time? — Linda, Casselton, N.D.

A: Fernleaf peonies, with their finely cut foliage and rose-red flowers, bloom earlier than standard, old-fashioned peonies, which gained them the nickname “Memorial Day peonies.” The time to dig and divide fernleaf peonies is the same as other peonies: around Labor Day in September.

If your peony is currently healthy, well-filled with shoots and blooming nicely, it’s not necessary to dig and disturb the entire plant. Instead, in September dig a portion from the plant’s outer perimeter for your neighbor, leaving most of yours intact with less disruption.

When weeds become entangled in perennial flowers, digging is often more effective than chemical sprays.
A reader asks what could be ailing these evergreen trees.