Monthly Archives: May 2021

Pacific Northwest Lawn Care Month-by-Month (Western Valleys)

March Through May

  • Feed the wild birds. Attracting wild birds to your garden is an excellent way to naturally control harmful insects. Allow wild birds such as starlings to peck at your grass as they are feeding on insects that are harmful to your lawn.
  • Irrigation systems. Check your irrigation system well before the warm weather starts to ensure that there are no broken pipes, faulty sprinkler heads or broken risers. Check sprinkler heads for adequate coverage and adjust or replace as necessary. Check your timer to make sure it is functioning so that expensive water wastage does not occur. Have your irrigation backflow prevention device tested. In some cities, this a yearly requirement.
  • Get your mower ready. Perform mower maintenance.Take your mower into repair shop to perform annual engine maintenance and blade sharpening. Do it early in the season when the repair shops are not busy and to avoid the spring rush, so that you will not be delayed in mowing your grass in the spring.
  • Dethatch your lawn. Once your lawn has dried out and it is not excessively wet—usually in April or May—dethatch your lawn of old roots and stems. Rake and remove the thatch. Lawn dethatchers can be rented  or your gardener can perform this service.
  • Aerate compacted soil. Lawn soil becomes compacted due to human and pet traffic as well as rainfall thus hindering water and fertilizer penetration and the growth of grass roots. This is why it is wise to aerate your lawn occasionally—preferably annually—for the best looking and most healthy lawn. Lawn aerators can be rented or your gardener can perform this service.
  • Remove perennial weeds. Once the grass starts to grow and on a dry day, spot treat weeds with an herbicide. Read and follow all label directions including wearing the recommended personal protection equipment (or PPE) when applying chemicals herbicides. At any time of the year, you can dig out the weeds by hand.

April or May

  • Overseed bare spots. When the weather begins to warm up, but are not too hot and there is still regular rainfall, and when the grass begins to grow, it is an excellent time to overseed bare or thin spots in your yard. Fall is the best time of the year to reseed bare areas of your lawn, while spring is the second best time.
  • Start mowing. Begin to mow your grass every week or as needed. For the best results, do not remove more than one-third of the top growth of  your grass at a time. Grass can be kept shorter during cooler weather, but when the hot summer weather begins, it is less stressful on the grass to allow it to remain at about two to three inches tall. This also helps the grass to choke out any weeds that might try to grow up through it.
  • Weed control. Annual weeds, such as crabgrass, grow from seed each spring. A well-timed application of preemergence herbicide to stop them from growing is called for at this time of the year. A good guideline is to spread the preemergence herbicide as forsythia blooms in your area start to drop.
  • Fertilization. Feeding your lawn at least couple of times a year is a must. One fertilization in the spring and one again in the fall is the minimum requirement to maintain a healthy lawn. 


Lawn grubs. If lawn grubs are an issue in your lawn, prevent further damage by applying a grub-control product that continues to work throughout the season. The best time to do this is while doing lawn maintenance activities in early June.

July Through September

  • Summer lawn maintenance. Summer is about mowing, watering, and pest control. Stay on top of mowing for a healthy lawn.
  • 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. 
  • Mowing. Mow once a week, removing no more than one-third of the height of the grass to avoid stressing it. Mow regularly to prevent weed seed spread.
  • Letting your lawn go dormant. 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. 


  • Weed control. Most perennial lawn weeds are more easily killed in the fall. Treat them with a broadleaf herbicide or pull them by hand.
  • Fertilization. If you only fertilize as part of your lawn maintenance once a year, fall is the best time to do it. In fact, your lawn will appreciate a light application of fertilizer in early autumn and again in late autumn.


  • Fertilization. When rains begin, fertilize with natural organic or slow release formulations. 
  • Lawn renovation. Late in the month, begin fall renovation including thatching and aerating if you were unable to do it in the spring. Rake and overseed bare spots, or install new seed or sod lawns.
  • Irrigation. As the cool weather begins, you can reduce the amount of lawn watering. Eventually, when the weather becomes cool enough and the fall rains start, you can stop watering and shut off  your irrigation system if you have one. Before winter, drain your irrigation system to prevent it from freezing.
  • Late-September Through Early November
  • Overseed bare spots. When the weather begins to cool down from the summer heat, yet while the grass is still growing, and the fall rains begin is an excellent time to overseed bare or thin spots in your yard. Fall is the best time of the year to reseed bare are of your lawn, while spring is the second best time.


  • Fertilization. Late in the month, apply winter fertilizer which is vital to maintain healthy turf. 
  • Mowing. Continuing mowing as needed while the grass is still growing if conditions are not excessively wet and cold.


  • Fertilization. Apply winter fertilizer if you forgot to fertilize your lawn the fall.  
  • Rake leaves. What more can be said about this?

December Through March

  • Perform mower maintenance. This is a good time to take your mower to repair shop for some annual engine maintenance and blade sharpening. Do it in the winter when the repair shops are not busy and to avoid the spring rush so that you will be ready to mow your grass in the spring.
  • Other lawn care. Avoid walking on extremely soggy or heavily frost-covered lawns to avoid damage to your grass.

May in the Garden—A To Do List

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, your garden, that you have been given the privilege of borrowing for a time. It is our hope that the following to-do list will help you to do just that.

Nathan, the Treevangelist, urges you to treat your spot on this planet like your own personal Garden of Eden. May it become your personal paradise. This is your divinely mandated responsibility.  Your trees, shrubs, flowers and the wildlife in your yard will pay you back as they express their smiling appreciation to you and yours by radiating their love, joy and beauty bursting forth with vibrant and verdant life. Below is a to-do list to help fulfill this mission.

Despite the fact that last month was our driest on record, the April showers that did not happen still brought forth May flowers. The cycles of nature are amazingly irrepressible. At this time of the year, nature puts on her finest adornments to regale the pollinators with tasty enticements to ensure the survival of the species. The most dour personality is sure to have their spirits lifted just by stepping outside and imbibing in the bright blue of the sky, the multiple shades of green and crimson foliage, along with the fascinating and captivating array of floral colors. Get outdoors and immerse yourself in it all—get intoxicated with the sights and fragrances along with the sounds of the mellifluous  birds. For a moment, let’s forget about the craziness of the world around us and say a prayer of thankfulness that sanity, consistency and predictable order still prevails in the garden. This can be great solace to the  wearied soul, to be sure!

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, our Facebook page at and our main website at 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 the Treevangelist

Tree and Shrub Care

  • 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.
Coast pine with new growth showing male pines and pollen.
  • Pine tree pruning. Don’t do major pruning of pine trees during the growing season, since this attracts sequoia pitch moth infestation.
  • 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.
  • Prune fast growing ornamental shrubs that are beginning to look shabby. You may need to prune them again in the early summer for a more neat and manicured look. 
  • Reparative pruning. Repair winter damaged to trees and shrubs.
  • 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.
Close up of a pink Rhododendron Flower
  • Rhododendrons. Remove old blooms (called “dead heading”). Though it  looks better aesthetically to remove the dead blooms, it doesn’t hurt the plants to leave them on.
  • Water trees and shrubs as necessary, even before the summer heat starts. This geographical region has entered a period of erratic rain patterns, so even during the typically consistent rainy winter and spring seasons, due to the long periods of dry weather, some tree and shrubs will need extra water. Vigilance is the key. Watch your plants for signs of drought stress, and then give them a drink of water as needed.

Plant Health Care

Good News Tree Service, Inc. provides full plant health care services as listed below.

  • Apple scab on ornamental crabapple and fruiting apple trees. The first visible symptoms occur on leaves in spring as pale, yellowish, water-soaked spots the size of a pinhead. These enlarge, becoming darker and smoky in appearance, later taking on an olive shade and ultimately a brownish black color. Spots may be any shape but are frequently circular. Young infections often show a radiating spread of fungal tissue through the leaf, and such areas later appear as irregular, brown-colored infections. Diseased leaves can be curled and distorted and often drop early. This fungal disease can also move into the fruit to produce a scabby effect, hence the name “apple scab.” Several fungicidal sprays are required to control this disease just prior to flowering and after flowering. 
  • Arborvitae Twig Blight: Spray in the spring and early summer when new growth starts at two week intervals. 
  • Bronze Birch Borer: Begin treating in mid-May through June. This is the only time of year that this beetle can be effectively controlled.
  • Cherry Leaf Spot: Spray cherry trees for leaf spot. Apply first spray at petal fall and two weeks later.
  • Cherry Tree Brown Rot Blossom Blight (Monilinia fructicola):Make 3 foliar applications starting at bud break and at 14 day intervals.
  • Coryneum Blight (Shot Hole Fungus) or Cherry Leaf Spot: This leaf blight affects ornamental and flowering cherry, plum and prune trees. Spray at petal fall, shuck fall and two weeks later.
  • Deep Root Fertilization: Trees and ornamental shrubs—deep root fertilize to promote lush, healthy-looking and vigorous crown growth. Urban soils tend to lacking in many of the nutrients that trees and shrubs need to survive. Many are malnourished or are starving to death, which is why they don’t look radiantly healthy are struggling with pest issues. Deep root fertilization helps to promote healthy-looking and pest-resistant trees and shrubs. The best time of the year to do this is in the spring and fall.
Red twigged Dogwood in bloom
  • Dogwood Anthracnose: Spraying with a fungicide at bud break and continue at 10 to 14 day intervals. 
  • Lawns: Fertilize lawns.
  • Leaf Blights: Spray trees and shrubs for fungal leaf diseases (e.g. powdery mildew, leaf blights, dogwood anthracnose, needle blights, etc.).
  • 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.
  • Photinia Leaf Spot: Spray with a fungicide as new shoots are developing at 30 day intervals.
  • Pine Dothistroma Needle Blight: Apply fungicide at just before bud break and a few weeks later according.
    Powdery Mildew: Apply a fungicides as soon as symptoms appear. Best efficacy occurs if used before symptoms appear. Use fungicide at 7 to 14 day intervals, or more often if conditions warrant it. If a plant is known to have had powdery mildew previously,  apply as buds start to open.
Photo of Japanese Maple leaves
  • Spider mites will start to become active as the weather warms. Systemic insecticides are available against this pest.
  • Tent Caterpillar: Apply systemic pesticide for season-long control.
  • Verticillium Wilt: Soil drench in the spring. Maples are especially susceptible to this fungal root disease as are cherries and plums.
  • Willow Twig Blight (scab): Apply two or three applications beginning when new leaves first appear at 10 to 14 day intervals.

Elsewhere in the Garden

Close up photo of a Hosta plant with variegated leaves.
  • Put slug bait around your flowers and tender perennials like primroses and hostas. 
  • 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.
  • Continue planting annual and perennial flowers.
  • Cut English ivy off of the base of trees. (This can be done any time of the year.)
Nuthatch bird in bird feeder
  • Feed the birds. Don’t stop feeding the birds even during the spring and summer seasons. Why? Even though we’re now past the winter season and there is more food available for the birds, having these feathery friends frequent your garden serves several purposes. First, they bring life and excitement to your backyard by turning it into a bird sanctuary. Second, your singing friends 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.
  • Start making plans for your vegetable garden. Once the soil has dried out, you can begin working it for planting our veggies. Usually this will occur in late April or early May and sometimes later depending on the weather. The earlier you plant, the sooner you’ll be feeding on delicious veggies from your own garden! 
  • This is a good time of the year to plant trees and shrubs. 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.
  • 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.
  • Fertilize your ornamental shrubs with a slow release fertilizer. If the shrubs have a layer of barkdust or other mulch around them, rake the mulch away and apply the fertilize to the bare dirt, so that it actually reaches the plant’s root zone.
  • Plant new lawns. Fertilize your lawn. Aerate and dethatch.

Care of Roses

  • Dealing with rose 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!