Ask the Master Gardener: Any solutions for removing weeds without losing my hostas? (2024)
Q. I have tried pulling the weeds out of my hostas, but they break off. Any solutions for removing weeds without losing my hostas? — S.W., Springfield, Mo.
Answer byMasterGardenerMark Bernskoetter
Removing an infestation of weeds (like Bermuda grass) from hosta can be tricky when you find them lodged tightly among the hosta roots.If you just pull, either the weeds will simply break off, as you experienced, or more tender plants may be uprooted along with the weeds.
Herbicides will likely damage or even kill your desirable plants, so thatisusually not an option, either.
Digging up the hostas may prove to be the best solution.Then you can go through them and tease out the weeds and their roots and replant the hostas.Clearweeds out of the areabefore replanting and be sure to mulch the area after replanting to help minimize future weed problems.
Hostas are very forgiving about being transplanted, and it should notstunt them too badly for this growing season.
Q. I purchased junipers and thuja ornamental trees last year.Nowmost of the plants have ablack speckledcolor on the lower springs as if spray-painted. — P.B., Nixa, Mo
It sounds like your plants have a fungal disease known as tip blight, a common problem of junipers and thuja(orarborvitae).
The dead foliage becomes ash-gray and develops small black spots, called pycnidia, which are pinpoint in size.Cankers may develop between living and dead branch tissue.
The fungus overwinters in infected plant parts. The disease can become a problem anytime foliage is wet,asinspring and fall during rainy weather.
During wet weather, spores ooze out of the black pycnidia in white tendrils and are blown or splashed onto needles or may be spread on pruning tools.Mature needles are not as susceptible to the disease as young, succulent new growth.
All blighted twig tips should be removed about one inch into live wood and burned or buried to eliminate the source of infection. Viable spores of these fungican survive onbranches that have been dead for as long as two years.Pruning or shearing should be done on a dry day to reduce spread of the fungus to other plants.
Unfortunately, once you prune junipers orarborvitae to the point where you remove all the green from a stem, that limb will usually never again put on any new needles.
Fungicides are needed when new flushes of growth occur in spring and fall, or after shearing,until new growth is mature.
To prevent the disease, keep foliage as dry as possible to reduce problems — overhead irrigation should be avoided.Do not buy plants with dead or dying tips.Do not plantthemin heavy shade or poorly drained soils.Prune and space plants to encourage good air circulation and rapid drying of foliage and grow resistant varieties.
Readers can pose questions or get more information by calling 417-874-2963 and talking to one of the trained volunteers staffing the MasterGardener Hotline at the University of Missouri Extension Center in Greene County located inside the Botanical Center, 2400 S. Scenic Ave., Springfield, MO 65807.
Digging up the hostas may prove to be the best solution. Then you can go through them and tease out the weeds and their roots and replant the hostas. Clear weeds out of the area before replanting and be sure to mulch the area after replanting to help minimize future weed problems.
Vinegar burns the tops of plants. It doesn't move to the roots and roots remain alive.. Hostas have robust roots and may resprout when their tops are burned back. Repeatedly burning the tops back will eventually kill the hostas.
That's a little bit disappointing, but it's not at all surprising [10:13] because again, Roundup is a systemic. It's going to kill the entire weed. It's absorbed in through the leaves, goes to the stems and the roots, and kills the whole thing. Vinegar, all it's doing is just killing the leaves and that's it.
Just wait until hostas fade this fall. When leaves are all yellow/brown, spray the grass with Roundup. Grass usually is still active for 2-3 weeks after hostas are finished for the year. If it is that heavy with grass, you may want to cut back the hostas before spraying, to make sure all grass is hit.
You could dig them out individually, or you could offer them to a garden club or similar group, or you could spray them with a nonselective herbicide containing glyphosate.
These summer annual weeds are best controlled by hand weeding a bed and then thoroughly mulching it with 2 inches of mulch. The thickness of the mulch is important for effective control.
There are some grass specific herbicides you can use and now is an ideal time to use them. The key is to let the grass green up and start to spread and then treat. Brand names include Grass-b-gone, Over the Top, Ornamec and Vantage. This will kill the grass without damaging your daylilies, hostas or peony.
Preen should not be used on flower seeds. It can be used after flowering plants have germinated and are 2-3 inches tall. Preen may also be incorporated into the soil when seeding vegetables or applied after mulching beds. By applying Preen as early as possible, you can eliminate the need for hand‑weeding.
Vinegar is acidic and will eventually kill most broadleaf weeds, but the acid will kill the leaves before reaching the root system, and the weeds may grow back quickly. For longer-lasting removal, mix 1 cup of table salt with 1 gallon of vinegar. Salt dries out the weed's root system.
The Takeaway. To eradicate weeds effectively, the roots need to be killed, not just the top growth, which synthetic weed killers do successfully. The bottom line is that mixing vinegar with Epsom salts or table salt and liquid dish soap does not make a safe, effective weed killer.
Kills weeds rapidly, causing death in 24 hours. Effective for killing small seedling-stage annual broadleaf weeds. Vinegar biodegrades and breaks down quickly (not salts, however).
We are always asked about how to protect hostas from being eaten by slugs and snails. Garlic wash is a really simple, cheap and safe way to protect your hostas without using harmful pellets.
These mollusks love hosta leaves. Since slugs are nocturnal and hide during the day, gardeners may not see the slugs themselves but only the evidence of their feeding. Look for smooth but irregular holes along leaf edges or between veins. Sometimes, entire leaves are sheared off at the stem.
Buy a spray container of insecticidal soap at any home improvement store. I also sprinkle diatomaceous earth on the soil around the base of my hostas to control slugs.
Vinegar as an herbicide: White vinegar which is about 5% acetic acid and does a nice job of burning the tops of plants, but not their roots – so a larger weed will live right through a spray even though it will look bad right after the spray.
In this case, chemical weed killers can offer a quick and effective solution. Opt for a systemic herbicide like glyphosate; the leaves of the hostas will absorb this chemical and transfer it down to the roots, thereby killing the entire plant.
How to Use Vinegar for Pest Control. When utilizing vinegar as an insecticide or repellent, you should always mix it with water, generally at a 50/50 solution. This mixing is necessary because vinegar can damage plants, and furnishings and irritate the skin when used without being diluted.
You can also sprinkle diatomaceous earth ($17, The Home Depot) around your hostas. Slugs don't like the sensation of the tiny, sharp crystals in this nontoxic powder. Ground-up eggshells can have the same effect.
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