How to plant more trees in your city
Turbocharge tree planting by giving away free trees.
Trees are crucial to making any neighborhood or city healthier and more pleasant. Some of the obvious benefits of trees include:
providing oxygen
removing harmful pollutants from the air
mitigating flooding by absorbing runoff from rain
creating a habitat for birds and other local wildlife
reducing noise
providing shade and lowering temperatures in the summer, and reducing “heat islands”
increasing property values
improving the physical beauty and comfort of the landscape
The impact of trees on the well-being of people is tremendous: research shows that people who spend more time around trees have improved moods, enhanced cognition, lower stress, and even less frequency of chronic diseases. Even further, a higher prevalence of trees has been associated with lower levels of crime: a 2001 study from the University of Illinois found that in Chicago area housing projects, “buildings surrounded by foliage saw 48 percent fewer property crimes, on average, and 56 percent fewer violent crimes than buildings with low levels of vegetation.”
It should not be a hard argument to convince anyone that trees are good and we need more of them. Of course the answer is to develop a program to plant more trees. But how do you do that? Read below to learn how to plant trees correctly, how to create a successful tree planting program, and most importantly how giving away free trees is the secret to turbocharging your tree planting.
How to plant trees correctly
Trees come in a variety of sizes, measured by the diameter of the trunk. Experts refer to this measurement as the “caliper” of tree: for example, a tree with a 2” diameter trunk has a 2” caliper. The tree roots are commonly referred to as the “root ball”. Farms and nurseries that grow trees might grow young trees directly in plastic pots ready for transport (trees that will be sold and planted before they “mature” or get too large for a person to carry) or else directly in the ground (trees that will be sold and replanted at a much larger size or caliper). Larger trees not in a pot will have the root ball covered in a burlap sack during transport.
To plant the tree, first find the right place: make sure it is far enough from obstructions or other infrastructure such as overhead wires, underground pipes, or nearby structures and buildings. Also make sure it is not too close to other trees- remember that as trees grow they expand up AND outward. If a tree is being planted along a sidewalk or street, make sure the hole in the concrete or asphalt is at least 4 feet by 4 feet, but ideally much larger. Trees need water, and concrete and asphalt limit the amount of water that can penetrate into the soil, and while the tree root ball may physically fit in a smaller hole, the ground needs surface area to absorb rain water. Remove as much of the burlap sack or any other protective materials before planting so the roots can grow outward and so that water and nutrients can reach them. Then dig a hole wide and deep enough to contain the entire root ball- obviously the roots need to all be under ground. Cover the top of the root ball with soil. Give the tree a deep soak of water and add fertilizer at planting and then at regular intervals. Different tree species need different amounts and frequencies of watering and fertilizing, so check with the nursery that supplied the tree to know exactly how to care for the tree.
The last step is to “stake” the new trees. Younger trees often have weaker trunks that are susceptible to breaking under even mildly windy conditions. To stake a tree, metal or wood poles are put into the ground next to a tree (on two or three sides) and the trunk is stabilized by tying the trunk to the stakes with wire or rope or string. This is usually only needed for about a year after planting/replanting. Make sure not to tie the tree so tight that the trunk is damaged.
Sometimes trees will come with a watering bag at the bottom of the tree when it is planted. The bags are meant to be filled with water and that water is meant to be released slowly into the soil. Bags are filled with a hose and not by rain water (only used during manual watering). Experts do not agree on if bags are helpful- sometimes bags can damage the trunk, but also why not just put water directly into the soil.
How to pick the right tree
Certain trees are more suitable for certain types of environments. For example, when planting in a more urban area filled with sidewalks and streets and buildings, select trees that have “taproots” or root systems that grow mostly down instead of outward in a way that might cause damage to nearby infrastructure. For example, Ginko trees have a large taproot that makes them suitable for tight spaces; maple trees on the other hand have very shallow and wide root systems which can damage nearby sidewalks, streets, buildings, and even underground sewer and water pipes. Urban environments can also expose trees to air and water pollution, not just from cars and trucks but also from pet waste and salt from snow storms and much more. Make sure you have a tree that can tolerate that type of environment. Here are a few common street trees that are great for urban environments:
Ginko: make sure to select male Ginkos as females produce foul smelling fruit
Honey Locust: very tolerant of air and soil/water pollution
Oak: some of these can grow very large so make sure they have enough space
Crabapple: beautiful white flowers in the spring but make sure to find the variety that does not produce fruit)
Palo Verde: unique green bark and yellow spring flowers; most often found in Arizona and the Southwest United States and Mexico
Maple: gorgeous and stately shape and stunning fall colors, but shallow and wide root systems will require more open areas
Avoid these trees at all costs:
Bradford pear: exceptionally weak branches that break and fall off in regular wind storms; also invasive and grows like a weed
Sweetgum: produces a large amount of “gumballs” (seed pods) that get very messy
Mulberry: produces allergy inducing pollen and a ton of purple fruit that birds love but that stains everything and also grows like weeds
Any tree that produces fruit (unless it will be on private property and you can properly maintain it)
Silver Maple: a variety of maple that has much weaker branches and much more invasive root systems
Cities usually have an approved street tree list and some even have banned certain trees from being planted (Bradford Pear and Mulberry are two commonly banned trees).
How to create a successful tree planting program
There is more to planting trees than simply digging some holes. Here’s the secret recipe:
effectively communicate the “why”. Tree planting does cost money, and someone somewhere has to approve this funding. If you can properly communicate the “why” from the above points, the decision makers will need little convincing. In addition to simply sharing this article with your city council, two additional ways to further demonstrate support for this are 1) resident feedback surveys asking what the city should prioritize (hopefully trees and the environment are high on that list), and 2) performing third party studies to show your city needs more trees (“tree canopy studies” are very common and it is likely your city has done one recently).
Set an ambitious yet reasonable and feasible goal. Find out how many trees you plant now every year (it might be zero, but probably not) and determine how many more you could reasonably plant if you had additional resources. Think big and aim for something ambitious, but not so much so that you set yourself up for failure.
Find out exactly what you need to plant more trees. Is it just a question of finding more money in the budget and buying more trees, or will you need to hire additional staff or contractors? Where will you plant them and do you have the space? The City might have land, but what about along state highways or on other state or County property? Do you have an airport, and if so is there space around that? Perhaps residents and other property owners be willing to plant them on private property (more on this below).
Find a vendor that can supply the most amount of trees at the lowest price. Pro tip: when going for volume, younger and smaller trees are not only less expensive but are much easier to plant. Although they will take some time to provide the full list of benefits above, younger trees catch up to older and more mature trees quite quickly and have a higher chance of survival than larger more mature trees.
Find a vendor that can plant a lot of trees. This sometimes is not the same as the vendor that supplies/grows the trees. Also make sure that vendor does two things in addition to planting trees:
waters your trees. Trees need water, particularly those that are newly planted. A common approach is for a tree planting vendor to water newly planted trees only if it doesn’t rain enough (for example if your city does not get a certain minimum amount of rain in a given week or month, the vendor will water each tree planted within the last 2 years).
provides a warranty to replace a tree if it dies within the first 2 years. 10-20% of newly planted trees will not survive for a lot of potential reasons (the stress of being replanted, not being planted correctly, not enough water, too hot during planting, etc). Without this warranty, you might have to spend your entire tree planting budget replacing the ones you just planted that did not survive.
Make sure you have a variety of different tree species. Also known as “biodiversity”, a variety of tree species will not only make your city look great but will also help mitigate any issues or diseases that affect any particular tree species. For example, the emerald ash borer beetle destroyed tens of millions of ash trees in North America, and dutch elm disease is a fungus that has killed millions of elm trees in North America and Europe. Imagine if a city only planted one of these types of trees- it might not have any trees left! Sometimes the best way to mitigate these issues is by having different types of trees that might not be as susceptible.
Plant trees in the spring and fall only. Trees planted during hot temperatures are more susceptible to shock and death because of the stress caused by the heat AND replanting. Fall/winter/spring planting is best while trees are dormant (all the leaves have fallen off the tree), but it may not be easy or possible at all to plant trees when the ground is frozen hard. Many cities with all four seasons will stick to plantings in spring and fall only, but warmer climates can also plant through the winter.
The secret ingredients for success
Hiring a tree planting contractor to plant a tree might cost you a few hundred dollars per tree (in addition to buying the tree in the first place). It costs nothing more to give them away or to make someone else do it. Here are four ways to do this:
Give away free trees to residents and property owners. This is by far the best way to plant more trees and get residents excited about doing it. So many people already want to plant trees, want to make their neighborhoods more beautiful and healthy, and most importantly want to participate in making their neighborhood and city a better place. And a tree in someone’s backyard has the same amount of benefit as a tree along a public street. In addition, every single person who plants a free tree will not only take care of it for you but also becomes a cheerleader for the program and for the city.
Require new development projects to plant trees. This is a simple change to the zoning code that would require new development projects of a minimum size and area to add new trees onto that property as a part of that new development. For example, a new multifamily building along a busy city street would be required to plant 1 tree every 15 feet along the sidewalk.
Require property owners to replace trees if they are cut down. If a new development project is seeking to cut down a large number of trees to make space for new structures to be built, require the project to plant new replacement trees (within reason) either on the property or somewhere else. Obviously this needs limitations and restrictions but generally replacing some amount of trees cut down with some amount of new trees is important to preserving tree canopy.
Create a Tree Trust Fund. If a property owner cannot comply with points 2 and 3 above (for example if space is limited on the property), the property owner could contribute a similar amount of cash to a trust fund that can then fund planting those same trees somewhere else and by somebody else. This “Tree Trust Fund” can be funded in other ways, including through local philanthropists or other types of grants. The key is that this trust fund creates a mechanism to raise money for tree planting outside of raising taxes.
How to create a free tree giveaway program
Think of your free tree giveaway events as a party with trees as the “gift bag”. Pick a location where you can stage a large area of trees where people can pull up cars directly to where the trees are stored. RSVPs are important in order to plan exactly how many trees to bring and how many people will be able to come get trees (assuming you have a limited supply of trees). An event website helps describe the “why” but also provides resources on how to care for trees. Pick trees to giveaway in accordance with what you learned above about picking the right tree- remember that smaller is better to make transporting and planting them easier. These giveaways can occur in spring and fall, ideally at exactly the right time to plant trees in your city (trees are not to be stored in a garage until the right time to plant). Also, as with every party, take lots of pictures and post them on social media!
How do you know if you are planting enough trees?
The most well resourced cities in the United States can plant thousands of trees a year. While City Manager of Kansas City, MO we set an ambitious yet achievable goal of planting 10,000 trees in 3 years (we ended up planting over 11,000!). One of the biggest rate limiting factors for planting new trees is finding space, and Kansas City is blessed to have a lot of land and a lot of space for more trees: gorgeous parks, wide boulevards with robust center medians, and lots of single family homes with big yards. Not every city has this type of tree planting opportunity!
Happy planting!
