Tree Planting & Care
Our Top Five Tips for Tree Care and Planting
- Plant a tree in a space it will thrive and where is has room is grow.
- Fall, once the rain returns, is the best time to plant.
- Establish trees by watering them two times per week in the summer months for the first five years, to help them survive.
- Mulch is a useful tool to help provide nutrients, reduce weeds, and add more water to the soil.
- Mature trees need care and can benefit from supplemental watering during the hottest days.
If you are planting and caring for trees in neighborhoods– in residential yards and along streets at home, school, work, or other shared neighborhood spaces–read on for details on the practices we recommend.
A well-placed tree can help conserve energy, provide a visual screen, and provide years of beauty. However, a tree placed in the wrong place can be harmful and potentially expensive! The small tree you plant today will someday grow tall, and its roots will be as expansive as the tree's branches. Make sure you select a location with adequate room to grow above and below ground. Consider surrounding trees and structures, how much light your site gets, and what its soils are like.
If you have the space, consider planting large and evergreen tree species first, especially conifers! Research has shown that large trees provide Seattle with the most benefits. Because evergreens hold their needles and leaves through the winter rainy season, they reduce the most stormwater runoff and provide many other benefits for wildlife and people.
Watch our webinar for more information. Ultimately, choosing the right tree for the right place can make our urban forest more resilient as Seattle grows denser and its climate changes.
Fall is the best time of year to plant a tree in Seattle. Trees planted in October-February benefit from our fall and winter rains, developing a stronger root system that helps trees survive the hot, dry summer. Watch a video of our Planting and Care webinar to learn about the best methods for helping trees grow strong and healthy.
Before you plant a tree, call 811 or submit an online dig ticket at least two days before planting. Make sure to plant your tree at least five feet away from any marked utility lines. Note: your sewer line will not be marked by calling 811. Use the Side Sewer Cards and Maps tool to locate your side sewer line and stay at least five feet away. You don’t need a permit to plant a tree in your yard, but you do need a permit from SDOT to plant a tree in the planting strip or right of way.
When you’re ready to plant, follow these best practices to give your tree its best start in life:
- Remove the tree from the pot. Gently roll the pot from side to side on the ground then slowly slide the pot away from the roots. Be sure to carry/move the tree by holding the pot, not the tree's trunk.
- Locate the trunk flare and remove any soil piled on top. The trunk flare is the area where the first major roots extend out from the trunk. Try not to confuse the trunk flare with the graft point, which sits directly above the trunk flare. Once planted, the trunk flare should sit just above the top of the soil.
- Examine the roots. Roots that are circling should be redirected to grow out into the soil. If this is not possible, it is better to cut a root than to allow it to continue growing in a circular fashion. If you cannot separate the roots and the roots are circling around the edges of the container, cut an X across the bottom of the root ball and then four vertical slices along the sides of the root ball with your sharp-edged trowel or hori hori.
- Dig a shallow, wide planting hole. Dig the hole only as deep as the root ball and about two to three times as wide. Do not loosen the soil at the bottom of the hole, which will cause the tree to sink over time. If you are removing turf, knock any loose soil off of the turf and into the soil pile for re-filling.
- Remove any bamboo stakes or tags still attached to the tree. These will not help support your new tree and will harm your tree down the road.
- Place your tree into the hole and orient. Think about where you want the main branches to point. Be sure the trunk flare is above ground. A buried trunk flare will rot over time, impacting the health and safety of your tree.
- Fill in the hole using the soil from the hole you dug and pack in firmly. Do not put amendments such as fertilizers and compost in the hole. These can harm your tree. Amending is best done with a thin layer of compost as a top dressing.
- Water your tree. Give your new tree 15 gallons of water to ease the roots into their new home and help remove excess air pockets.
- Mulch. Spread two to three inches of arborist wood chips around the base of your tree, keeping it about a hand’s width away from your new tree.
- Stake your tree only if the tree cannot remain straight without support. If you do stake, place your ties at the lowest point on the trunk where the tree can be held upright. This will let the trunk move with the wind and grow stronger. Use broad, flexible ties and keep the ties loose on the trunk to avoid damage to the trunk. Remove stakes after one year.
Watering
The most important best practice to follow is watering. All new trees should be watered with 15-20 gallons of water twice a week for the first five summers after planting. This watering window usually starts in mid-May and extends through October. Water within a foot of the trunk and allow it to soak deep into the soil so that the water reaches the tree’s roots.
The most efficient way to water is to fill a 15-20 gallon watering bag twice per week. All participants of the Trees for Neighborhoods Planting Program will receive a free watering bag for every tree. Another efficient way to water is to use three, five-gallon buckets that have five-eight small holes in the bottom (use a drill or a hammer and nail to create the holes). Space the buckets evenly around your tree and fill with water twice weekly. Watering with a hose is best done as a slow trickle left on for about 30 minutes, preferably in the evening or morning.
Mulching
Mulching trees helps keep the weeds away, saves water, provides nutrients, cools the soil, and protects the trunk from lawnmower damage. Apply a three- to four-inch-thick layer of wood chip mulch in a doughnut shape around trees. Mulch should not be touching the tree trunk and should be kept a hands-distance away. Check out our video for further mulching instructions.
To Stake or Not to Stake
Most young trees to do not need stakes; only stake a tree if necessary to hold it upright. Be sure stakes do not rub against the trunk or branches, causing wounds which can lead to infection and tree death.
Please remove any bamboo stakes attached directly to the tree before planting. If you need to stake your tree, stakes should be placed at the edge of the planting hole. If stakes are attached too close, the tree will likely flop over as soon as you remove the stake. The goal is to keep the tree upright but still allow it to move in the wind. This helps the tree to develop strength to hold itself up over time.
When you’re ready to attach the straps, start low on the tree and gently move up the trunk until the tree straightens out. That is where you will attach the straps. Check the stakes and straps every season and adjust as needed to support the tree as it grows. Remove stakes after one to two years.
Pruning
Prune young deciduous trees (that drop their leaves in the winter) to create a strong structure and remove any dead, damaged, and diseased branches. Pruning a young tree is much easier and less costly than pruning a mature tree in the future. Poor pruning techniques, such as removing the top of a tree can seriously damage your tree and make it less safe. An arborist certified by the International Society of Arboriculture can provide expert tree pruning. If you plan to prune yourself attend a pruning workshop offered for free to all Trees for Neighborhoods planting participants. Pruning street tree branches larger than two inches in diameter requires a permit from SDOT.
Protect the Trunk and Root Zone
Remember to always protect trees from damage at the trunk (from things like lawnmowers and string trimmers) and the critical root zone. The critical root zone is the area extending from the trunk directly under the trees canopy where the most important roots are for nutrient and water uptake. Mulching around your mature trees locks in moisture and prevents weeds. Grass competes with trees by absorbing water and nutrients from the soil. Most tree roots are within the top two feet of soil and can be damaged by any activity that disturbs the soil.
Water on the Hottest Days
Even well-established trees need water in our hot, dry summer months. Water slowly, mornings and evenings, and make sure you water in the root zone and not the trunk.
Remove Aggressive Plants
English ivy is a common aggressive plant that can strangle your tree. Protect your tree by removing ivy using the example in this video.