Gardening season is on its way, and you may have questions as spring gets going. To ask one, simply go to the OSU Extension website, type it in and include the county where you live. A photo is very helpful.
Q: When is the best time for pruning ‘Endless Summer’ hydrangeas? I understand that regular hydrangeas should be pruned after they have bloomed in the fall and that ‘Endless Summer’ hydrangea should be done in either early spring or summer.
The previous year we didn’t prune them in the spring. They got very big and grew into each other along with creating problems with other adjacent plants. This forced us into cutting them back. Also, what is a good time for transplanting or replacing? – Multnomah County
A: The ‘Endless Summer’ hydrangea blooms on new or last year’s growth, so cutting now is fine. Each shrub will be about 4 foot tall and at minimum 4 feet across. Your plants are much too close to the building and each other to grow well. Crowded conditions stress plants, increasing disease and pest pressure, so proper spacing is recommended. Here’s the OSU Extension page about hydrangea care.
A newly planted landscape with appropriate spacing for mature plants would look bare to most of us the first few years. So often people over-plant at the beginning and then need to remove and re-space things as they grow.
Planting against the foundation and under the eaves is never a good idea. Doing so can holding moisture against the building and it can provide cover for rodents and insects and give them access to the house.
Many of your plants are too close for comfort, I would think. Here in western Oregon, you can move these smallish shrubs any time except May-September because it’s our hot and dry season. Dig a hole or prepare a container for the hydrangea, lift and replant it now. Extra summer water is a good plan, too. Our soil isn’t cold enough for most of the winter to stop root growth so replanting in winter is fine, but transplanting when the soil is saturated isn’t good. Find the less-wet weeks for that chore.
If you’re overwhelmed by which should stay and which should go, you can hire a landscape designer to make a sight visit or look up the growth habit and mature sizes of your shrubs and make your own decisions. You might find rearranging the plants is easy and fun.
– Jacki Dougan, OSU Extension Master Gardener
Mock orange hedge. OSU Extension Service
Q: We have a mock orange that experienced damaged during this past winter. One of the main branches has split at the base. I cut back and removed the outer branches to take off the extra weight. My question is how far back should I cut to the split? It appears the split reaches down to the soil level.
Is there a product I should apply to the exposed damaged area?
Also, when is the best time of year to prune mock orange. The plants were put in the summer of 2020 and have never bloomed. However, they have continued to grow and have become very leggy and need to be reduced by a 1/3 if possible. – Multnomah County
A: Your plant is a variegated Japanese pittosporum, sometimes called Japanese mock orange, and scientifically named Pittosporum tobira ‘Variegatum’.
There is no product to apply to damaged bark or a shrub’s trunk that has split. You can remove the one part you already cut back and take a “wait and see” approach to plant recovery.
Your shrubs are overgrown and regular pruning to keep them more compact is an option. Although as with hydrangeas, keeping a naturally large plant small with pruning is constant task, and one that often weakens the plant. Avoid sheering the tops, instead cutting back individual branches. Choosing plants that are the overall correct size is recommended.
It looks like flower buds are forming. Prune after blooming, as if you do it now, you’ll lose this year’s flowers. – Jacki Dougan, OSU Extension Master Gardener
Aspen trees can send out numerous shooters than travel long distances. Oregonian file photo. Rosemarie Stein/staff
Q: Several years ago, my neighbor planted an aspen tree on the border of my small yard. As a result, my front lawn is inundated with countless aspen shoots throughout the summer.
With my neighbor’s permission, I am considering the removal of the tree, understanding that it will likely force increased growth of the shoots. I have been advised that the proper method of removal would be to kill the tree in the spring and then cut it down in the fall.
To rid my lawn (approximately 200 square feet) of the shoots, I’ve been told to cut down the shoots as they grow and apply Roundup to each of them using a Q-tip. Since 30-40 shoots grow in a week (and more if I include garden beds), this will be a quite an unpleasant four-month ordeal, but one I’m willing to tackle if effective.
My questions are:
1) Would repeat applications of Roundup, although carefully targeted on the shoots, end up harming my lawn? It seems to me, that over the course of the entire summer that could pose a significant problem. I don’t want to kill my lawn in the process.
2) How long after removing the tree, could I expect the shoots to continue to grow? Years? Does each individual application of the Roundup kill the shoot permanently?
Since the shoots grow considerably faster than the lawn, my front yard looks like it is constantly riddled with weeds. I am desperate to solve this problem, but as a 75-year-old woman, I understand my limitations. I would appreciate any advice you could give me.
A: When you cut the tree, treat the stump (within an hour if possible,) just inside the bark (the cambium layer) all around the cut surface of the stump with a brush control product that contains triclopyr. This quick treatment is very important.
If you are having the tree taken down by a company, perhaps they can do that for you. That will reduce, though not eliminate, a burst of new suckers.
As for the suckers, they can be treated by the same product used on the stump, either by cutting them and then painting the tiny cut surface with a small watercolor-sized brush dipped in the triclopyr. This is a tiresome job at first but will get easier if you do it soon after the cut. You will need to get your neighbor engaged in treating on his side. This product will not damage grass as Roundup would. Please read and follow all label instructions. – Chip Bubl, OSU Extension Master Gardener
Q: Do squash bugs survive over the winter in central/western Oregon? I had squash bugs in my raised bed last year and I am wondering if I can create a hoop house this year to keep the bugs out. I don’t want the bugs from last year to come back. – Columbia County
A: Adult squash bugs can overwinter in Columbia County and the rest of western Oregon. They need winter protection under plant debris, so an early clearing of the debris in a raised bed might be enough to significantly reduce numbers.
If you are planting squash in a bed that did not have squash last year, and you clean the debris out, a row cover put on at planting should give you some protection if you plant squash or cukes there this year.
For the last several years, squash bug numbers have been much higher than normal. Not sure why. Here is a link with more information. – Chip Bubl, OSU Extension horticulturist
