Q: I just removed all that I could of an ivy (I presume it to be English ivy) hedge that filled a 20-by-8-by-8-foot area. It was a huge undertaking that I foolishly took on by hand. I’ve even attempted to remove as many roots as I can, but they seem to never end. It’s on a slope that we’re going to eventually landscape. Before we do that, we need to know the best way to get rid of the rest — or as much — of the root system as possible.
We’re thinking a skid steer or mini excavator may give us the best shot at pulling up as much as possible, including stumps, followed by a cardboard/mulch combo to hopefully rot it out/keep it down. We’re still formulating longer-term plans for what to do with the slope, but getting this thing killed off is the short-term goal. Do you think that’s a good option?
A: I think your plan to remove as much of the root system as possible with equipment is a good idea. Ivy is so hard to manage because even the smallest amount of root or stem that is left can resprout. You’ll want to keep an eye on this site for several years and stay on top of any resprouting.
What I am less confident about is the plan to use cardboard and mulch to smother the ivy. A few sources, including San Juan County’s Noxious Weed Control Program, suggest either tarping the site or using a very deep layer of mulch (at least 8-12 inches) to block the light and keep the plant fragments from resprouting. That depth of mulch may not be feasible on your slope (or your wood chip budget).
Will a cardboard-mulch combo function like a very deep layer of mulch to block enough light? That is an unknown. If you try the technique, use as thick of a layer of mulch as you can. Regularly inspect the area — especially the edges. Remove any tendrils or vines that sneak out from under the mulch as soon as you see them to starve out the root system. Since it’s on a slope, you may have to rework the mulch after heavy rain to ensure the area stays covered.
— Brooke Edmunds, Oregon State University Extension horticulturist
Tips to prevent powdery mildew
Q: What is the best product to prevent powdery mildew on honeysuckle? I have cleaned up the old leaves and dead material at the base already.
A: Cleaning up the fallen leaves and debris that may be infected is a good practice. Does your honeysuckle itself show signs of mildew?
If so, on a dry day you can spray the bush with a homemade baking soda and vegetable oil spray. Mix 1 tablespoon of baking soda and 1 tablespoon of any vegetable oil in a squirt bottle and fill with water. Shake the bottle each time you spray to keep the ingredients mixed.
The baking soda will kill the fungal spores and the oil will help the spray stick to the leaves longer. Spray both sides of the leaves. This is an organic spray and will not hurt insects, pets or humans.
Pruning and keeping a good airflow throughout the plant is essential to keep mold off the leaves. Is your plant evergreen, meaning it does not lose it leaves? These plants are hardy and can grow very fast, so airflow is something you need to monitor regularly. However, this time of year there should not be any new growth.
If your plant is not evergreen and has lost its leaves, it is a good time to prune because you can see where there are crossover branches. Clean your clippers with a little bleach and water first, and make your cuts at an angle so water will drip off the cut.
If your plant has not lost its leaves, look for areas where you can prune and open up the plant for better airflow.
Also, since you have cleaned the area at the base of the plant, some compost is a good idea, leaving about 6 inches of space from the plant. It will add nutrients to the plant slowly for good spring growth. Or you can use bagged soil in raised beds. Mound it about 4–5 inches high, about 12 inches away from plant. The space from the plant is so mice and other rodents do not gnaw on the base of the plant. Compost right next to it gives them cover to do damage.
— Sheryl Casteen, OSU Extension master gardener
Coddling of flower bulbs results in early growth
Q: I am growing flowers for the first time in the form of a cut-flower garden. I ordered ranunculus, anemones, tulips and daffodil bulbs. I soaked the anemones and ranunculus for four hours, then pre-sprouted them in a mix of potting soil and perlite for 12 days. Then I planted all the bulbs in my raised bed around the first week of November.
In early December, I put up hoops and one layer of frost cloth to protect them from the cold. I was shocked at how much above-ground growth there already is for the anemones and ranunculus (I was expecting the greenery in spring).
Is it normal to have green growth in December? I’m hoping my pre-sprouting process hasn’t tricked them into trying to bloom now. I am also curious if I should do any more frost-cloth layering.
A: You may be giving your bulbs more care than they need, and are messing with their natural cycles in the process. Soaking the bulbs fooled them into thinking it was bloom time, far earlier than is helpful. And they don’t need winter protection in our mild climate, so you can remove the hoops and save them for less hardy annual plants.
The Ranunculae family (which ranunculus and anenomes) is slightly less hardy than tulips and daffodils, and can be planted in early spring when the soil begins to warm. They don’t need to be soaked.
— Kris LaMar, OSU Extension master gardener
Ask an Expert is an online question-and-answer tool from Oregon State University’s Extension Service. To ask a question, visit extension.oregonstate.edu/ask-expert.