This guide is tailored for the western valleys of Oregon and Washington.
YOU can help to make the world a better, a more friendly, loving and beautiful place by being a good steward of the spot on this earth that you are privileged to be borrowing for a time—your garden. Nathan, the Treevangelist, urges you to treat your spot on this planet like your own personal Garden of Eden paradise. Then notice the joy that it will bring to you! This is your Divinely mandated responsibility. Your trees, shrubs, flowers and the wildlife in your yard will express their smiling appreciation back to you as they radiate love , joy and beauty bursting forth with vibrant and verdant life. The following garden checklist will help you to do just that.
Spring 2022 was a little wetter than usual—a good thing. But summer’s blast furnace started early again this year, and the heat wave still hasn’t abated—not such a good thing for the plants. Due to the erratic weather patterns of the past few years, the some plants are exhibiting signs of stress. Generally, plants prefer gradual changes weathewise, and struggle when weather patterns change too abruptly. Since the life forces in a tree move in the slow lane, trees are unable to acclimate to sudden changes, thus making them more susceptible to stressors like drought and pests. I’ve even noticed a few local otherwise hardy native oak trees turning brown and dying. Even though we had a wet winter and spring, this wasn’t enough to abate our prolonged drought that is still killing some native trees like Western red-cedars and Douglas-firs. Below, I tell you how to give your stressed trees a little extra TLC to help them get through this tough time in their long lives.
While you’re at it, take a few moments and scroll back through this same Good News Tree Service, Inc. blog and check out the archives for any tree and plant care articles that you may have missed. Also check out our YouTube channel at https://www.youtube.com/channel/UCvcu2lL9NpgoXQtUFYyQShw, our Facebook page at https://www.facebook.com/GoodNewsTreeService/ and our main website at https://goodnewstree.com. Please enjoy!
Readers’ suggestions on how to improve this list are gladly solicited. If you, the reader, have any suggestions for additions to this month’s list, please put them in the comments section of this article, and I will add them to the list. Thank you in advance! — Nathan Lawrence, the Treevangelist
The following photos will still be from the Pacific Northwest, but just a little further north up the coast all the way to Alaska including the Arctic Circle. My wife and I recently returned from Fairbanks and north, then worked our way south through the Denali area and ended up in Sitka, which is in the extreme SE panhandle area of that vast state. Please enjoy!
Tree and Shrub Care
- Birch trees. Thanks to the bronze birch borer beetle, a large number of the Pacific Northwest birch trees are dying. To make your tree less hospitable to this nasty and lethal pest, there are two inexpensive things you can do. First, apply several inches of mulch to the ground under the canopy of your birch tree. Second, with a whirly bird sprinkler, irrigate the area under the birch’s canopy. The more water the better, since birches are water-loving trees. Irrigate once a week for several hours during warm weather and twice during hot weather. These two actions will lessen the chances that the beetle will attack and kill your birches. The bronze birch borer beetle can be treated in the late spring, but treatments are expensive. Call Good News Tree Service, Inc. for more info.
- Dogwood trees. Monitor leaves for signs of anthracnose. As the summer draws on, the symptoms on the leaves get worse. (See more info below.)
- Maples (including Japanese maples). Monitor the leaves of all maples and other trees and shrubs for symptoms of the potentially lethal verticillium wilt fungal disease. If you see branch dieback, call Good News Tree Service, Inc.
- Mulch. Apply two to three inches of mulch around all trees and ornamental shrubs. This helps to fertilize the plants and feed the soil, and also protects them against weed growth and loss of water when the warmer weather returns.
- Pruning of trees and shrubs. You can do all aesthetic pruning of all ornamental shrubs and trees (except pines) at any time of the year including summer. Don’t over-prune the top crowns of thin barked trees (e.g. Japanese maples, flowering cherries), since the sun’s UV rays can cause trunk and branch bark dessication resulting in cracking and dieback of sapwood and even heartwood resulting in entry points for diseases and potential structural failure of branches and trunks.
Also be careful not to do major pruning during periods of hot weather, since doing so exposes tender leaves underneath that haven’t acclimated to the sun’s ultraviolet rays yet, since they have been shielded by the layer of leaves you’ve just removed by pruning. Sun scald of these tender leaves may occur, especially on southern and southwestern sides of the plant. Sun scalded leaves won’t kill the plant, but it looks unsightly and diminishes the plant’s ability to photosynthate (produce food for itself).
- Pruning of large trees. Most trees in the temperate western valleys of Oregon and Washington can be pruned anytime of the year. If you’re not sure what to do, or how to do it, call Good News Tree Service, Inc. for a consultation, pruning lessons or to have them do the pruning for you. It is likely best to wait for cooler weather to prune stressed or sick looking trees. Call us if you have questions about this.
- Prune fast growing ornamental shrubs (e.g., laurel, privet, photinia, laurustinus, barberry) that are beginning to look shabby. You may need to prune them again in the early summer for a more neat and manicured look.
- Tree and shrub removal and stump grinding can be done all year long.
- Trees. Have an ISA Certified Arborist with an ISA Tree Risk Assessment Qualification (like Good News Tree Service, Inc.) inspect your large trees for the potential of failure due to weak root systems and defects in trunks and branches. This can be done anytime of the year.
- Conifer trees that are drought stressed. The Willamette Valley remains in a prolonged drought. Large native trees (e.g., Douglas-fir, western redcedar, spruce, native firs) are getting stressed and some are dying. If you have a tree that is showing signs of drought stress (e.g. pitch globules exuding from the bark, excess needle drop, yellowing of foliage), then you need to water your tree to save it, or pay the high price to have it removed after it has died. With a whirlybird, impulse or similar sprinkler or soaker hose, saturate the soil under the tree out to the tree’s drip zone (i.e., the outer tip of tree’s crown) for several hours once or twice a week to achieve deep root watering. Typical lawn irrigation systems don’t put out enough water to adequately irrigate the deeper roots of a tree, so don’t rely on your irrigation system to proved the water that large trees need to survive.
- Watering. During the hot summer months, well established trees and larger ornamental shrubs need little or no watering. However, newly planted trees and shrubs will need watering for the first two to three summers until their roots get established. Regular lawn irrigation isn’t sufficient to give trees and shrubs the deep watering they need to survive the summer heat. During warm weather, deep water your new plants at least once per week. During hot weather, twice per week.
Plant Health Care
- Birch trees. At this time of the year, many birch trees are dying. This due to a birch killing beetle called the bronze birch borer. This pest has no natural predatory enemies and no inexpensive cure is in sight for this pest. The beetle is killing at least 60 percent of the birch trees in this region and yours may be next. In the previous section of this article, we discuss this issue in more detail.
- Deep root fertilization. Be careful about fertilizing shrubs (especially with quick release fertilizers) after the weather becomes too hot. Fertilizer will push out new growth, which will likely scorch in sun. This is a waste of fertilizer and plant resources.
- Dogwood trees. This popular garden tree is very hardy and has very few pests except for the dogwood anthracnose leaf blight (discussed below) and occasionally the summertime non-lethal powdery mildew that appears on the leaves. Two things can occur on the leaves of the dogwood tree that often alarm homeowners. First, sometimes the ends of the leaves may turn brown and die. This can be due to anthracnose (discussed below) or due to sunburn or leaf scorch. The latter condition occurs because the dogwood is a shade preferring tree, and when we plant them in the full sun, the leaves that are on the sunny side of the tree often get sunburned. Though unsightly, this will not kill the tree. Another symptom of the tree’s dislike for hot sun is that the leaves will fold in on themselves at the mid-rid of the leaf blade. This is the dogwood’s unique defense mechanism to combat water loss due to evaporation or transpiration. It appears as if the leaves are wilting due to lack of water. This may not be the case, since even trees that are irrigated regularly will take on this cup shape—especially leaves that are exposed to full sunlight. Leaves that are not in the sun’s light will usually stay flat and unfolded.
- Dogwood anthracnose. If you missed the spring sprays topical fungal sprays, and you see signs of anthracnose on your tree’s leaves (reddish, purplish, brownish splotches), you can spray your trees with a basal bark fungicide. Call Good News Tree Service, Inc. for information on this treatment.
- Monitor trees and shrubs for insect pests. Piercing and sucking plant pests (e.g., aphids, lacebugs, scales, weevils, mites, etc.) are now out and active. If major infestation occurs, plan a course of action to treat your trees and shrubs against these pests. Small numbers of piercing and sucking insects are not harmful to plants. In fact, they provide food for the beneficial, predatory insects that feed on them. To control harmful insects, one can apply systemic insecticides against piercing sucking insects (aphids, lacebugs, scales, weevils, etc.) via soil injections (one treatment gives season-long control). If applied according to label directions, this will kill only the harmful and not beneficial insects.
- Spider mites will start to become active as the weather warms. Systemic insecticides are available against this pest.
- Verticillium wilt. The fall is the best time to treat, and spring is the second best time. Maples are especially plagued by this disease. During hot weather, symptoms include smaller than normal cupped leaves in the upper canopy, often with the death of the entire branch occurring.
Elsewhere in the Garden
- Birds. Feed the birds. Dutifully maintain your bird feeders. Bring life and excitement to your backyard by turning it into a bird sanctuary. The birds will thank you for your generosity by providing you with hours of entertainment, and by eating insect pests that harm your ornamental trees and shrubs. Birds in the yard are not only fun to watch, but they perform the vital task of eating harmful insects. Keep bird baths full. In hot and dry weather, birds need water to drink and to bathe in.
- Flowers. Water and fertilize annuals and perennial flowers. The hotter the weather, the more water they will need. Flowers in pots and hanging baskets dry out especially quickly, and so need watering every day or two.
- Ivy. Cut English ivy off of the base of trees. (This can be done any time of the year.)
- Mulch. Apply two to three inches of mulch (e.g. bark dust, garden compost or wood chips) on all of your shrub beds. Covering bare dirt areas in your yard with mulch helps to prevent soil compaction from rains, and weed growth, and helps to enrich our heavy clay soils.
- Planting. This is a good time of the year to plant trees and shrubs as long as you keep them well-watered. Visit your local nursery and select your favorite ornamental shrubs and shade trees. After planting your new shrubs, just make sure that you water them well immediately and regularly subsequently for the first two or three summers until their roots get established. During warm weather (in the 60s to low 80s), deep root water once per week. During hot weather (mid-80s and higher) deep root water at least twice per week.
- Slugs. Put slug bait around your flowers and tender perennials like hostas.
- Pests. Spray or treat roses with a fungicide as needed preventively to insure protection against fungal pathogens such as black spot, powdery and cottony mildew, rust and spot anthracnose. Apply a fungicide only after the rose has put out several inches of new growth. Excellent choices of both organic and inorganic fungicides are available at your local garden center or nursery. Some fungicides require spraying in the early spring as the new growth is emerging. Major plant pests include mites, aphids, thrips, rose slugs, leaf rollers, rose midge, spittle bug and sawfly. Determine what pest or disease your rose has, do some research online if necessary to ascertain this, and then visit your local garden center or nursery to find the right product for the job. Always read and follow all label directions. It’s the law!
- Dead heading. As needed, remove spent flowers after they are done blooming.
- Fertilize. In late August, fertilize roses again.
- Irrigation and pest control. During prolonged warm, dry weather, deep root water your roses at least once a week. A rose needs five gallons of water per plant per week. During hot summer weather. Spray roses with water (not in the morning, though) to cool them down, and spray top and undersides of leaves to wash off pests such as spider mites and aphids.
- Maintenance. Summer is about mowing, watering, and pest control. Stay on top of mowing for a healthy lawn. Mow once a week or as needed. Remove no more than one-third of the height of the grass to avoid stressing it. Mow regularly to prevent weed seed spread.
- Irrigation. Water deeply, slowly and as infrequently as possible. Try to avoid watering established lawns more than two or three times per week if possible except during extremely in hot conditions. It is not a bad idea to let the soil under your grass to dry out for a short time in between watering as this forces the grass roots to grow deeper in search of water thus making for a more drought tolerant lawn. It is best not to rely on timers for irrigation as temperatures will dictate water needs in addition to lack of rainfall. However, timers are helpful if you have lawns areas that are to large to micromanage or you will be gone for a period of time. If you want to save on your water bill during the summer months, you can skip watering your lawn if you don’t mind it turning brown. It is not dead; it is merely sleeping or in a dormant state. When the rains start up again in the fall, your lawn will turn green and start growing again.