How & Why to Plant Trees in Your Sustainable Landscape
When I was twelve years old, the ten of us lived in a four bedroom house with a small camphor tree across the sidewalk and a big pepper tree in our patio. I discovered I could climb the pepper tree to reach the roof of our house, or I could climb the vines on the other side of the house and walk over the roof to the shade of the pepper tree. Alternatively, if I needed to be within reach of someone calling me, I would just climb the camphor tree by the sidewalk with a good book and stretch out on one of its limbs.
This taught me how valuable it is to have trees somewhere in your yard for that and many other reasons: birds, flowers, fruits, shade, swings, tree houses and more. This article will show you how to choose trees, how to take care of them, how they benefit us, and why it's more important to plant native trees in a sustainable landscape than exotic ones.
Sustainable Landscape Design & Benefits
The main goals of a sustainable landscape are to conserve water and energy, reduce waste, decrease runoff, and provide food and shelter for native fauna. In addition, you'll want your landscape to be beautiful.
Trees can help with many of these things, including providing shelter, shade, food for humans and critters and, if they're native, conserving water in irrigation. They can replace lawns, which will also save you a lot of water.
In addition to planting and watering them properly, one way to keep native trees healthy is to install companion plants that help provide protection from insects and increase the kind of nutrients in the soil that the tree needs. The life that surrounds and protects a tree in its natural habitat - flora (plants) and fauna (animals) - is called a "biome."
Native Tree Biome
Researchers studying the biome of the ironwood tree in Arizona's Sonoran desert discovered that the tree has a way of actually choosing the plants that grow around it, creating subtle chemical changes in the soil and smell of the air to attract the right plants and birds (bringing plant seeds). The plants that surround each tree each provide a different benefit - attracting beneficial insects or discouraging harmful ones, providing extra nutrition in the soil that the tree needs, or attracting bees that help fertilize its fruits.
If this is true of other trees, too, then discovering what a particular species' natural biome is, and planting it in your yard, could help the tree grow healthy. You could plant either the native variety of companion plants or cultivars made for landscaping (or a combination).
In California we have burgeoning flocks of wild parrots. These parrots are thriving, not because of native trees, but because of the exotic tropical trees that Californians have planted over the years. It's the tropical trees that provide the right fruits and nuts for parrots to eat, and give them their favorite roosting places, otherwise they would have died out long ago. It also guarantees that they won't be a threat to local fauna . . . unless humans plant only exotic trees and let the native ones die out.
California's native biomes are primarily fir and pine in the mountains; redwood, cypress, and oak in the coastal areas; and dry willow and Joshua trees in the desert. There are other native trees as well, but these provide the primary biomes.
California Oak Biome:
- Under Oaks | Mostly Natives Nursery
When development occurs in oak woodlands the native flora is often disturbed and needs to be restored. There are a few simple rules that should be kept in mind when doing this in order to maintain the health of your oak tree.
Finding the Right Native Tree For You
Whichever type of tree you choose to plant, for its survival it's important to choose one that fits the nature of your landscape. So the first step is to examine your yard to determine how much sun it gets, how much wind, how much water, and when each event occurs during the day and year.
Then you need to look at the space you have for a tree to grow, including physical structures and hardscape on the ground, any major pipes under the ground, and any wires stretching across your yard in the air. This will tell you the maximum size a tree's roots and crown can be.
To find an indigenous tree of that size and with those weather requirements, go hiking in the hills nearby to see what's there. Or go to a native nursery in your area, specifications in hand, and ask them.
To find out what the tree's biome is (whether a new one you're planting or one already in your yard), search online for articles like that linked above. Better yet, while you're hiking in the hills, find your tree and look to see what grows around it. Take photos of the leaves and flowers of each plant, then take those to your nursery and ask them to help you identify them. Nursery assistants can also help you to identify garden hybrids of those plants. Once you've chosen what you want in your yard, it's time to figure out where exactly it will go.
Choosing a Location to Plant
Here are essential questions to ask when choosing the best place to plant your tree.
- Which part of your yard provides the same sunlight, soil, water, and shade conditions needed by the tree you've chosen?
- Can you permanently modify any less-than-ideal condition? The goal is to make it as easy as possible for the tree to take care of itself.
- If the whole yard is pretty amenable, then what is the major service you want that tree to provide?
- Shade for the house? Plant it on the west or south side.
- Catching runoff? Plant it downhill of the lawn in a dry patch of its own.
- To build a swing or treehouse when it's big enough? Plant it in the backyard and find a way, other than grass, to cushion any falls.
Be careful with grass near trees (unless grass thrives naturally in your locality). If you have to irrigate, you'll most likely cause problems for the tree. Trees like to be watered "deep and rare," not every day. Nor do they like to have water on their trunks - it softens the bark and lets insects eat their way through.
Preparing the Site & Planting Your Tree
Choose your time for planting carefully. In most locations, fall is best, when the weather is beginning to cool. Make sure you water your tree while in its container, so it doesn't start dying before you plant it.
The best way to plant your tree is to create a little hill with a wide trough surrounding it. That way you can fill the trough with water when the tree needs it, and the water can sink down without rotting the trunk. Here's how:
- Dig a deep, wide hole - a little deeper than you estimate the roots will be, once they've straightened out, and about twice as wide as the tree's container. Make a little mound in the middle of the hole for the tree roots to sit on and spread out around.
- Fill the hole with water and leave it to soak in overnight, then repeat. If your soil has a lot of clay in it, check the sides to make sure they're not slick. If they are, break them up a little with a forked tool. You want the sides to be loose enough that roots can penetrate and grow sideways.
- Next take your tree out of the container, removing any tape and stakes. With a helper holding the tree, gently separate and straighten the roots. As your helper lowers the tree into the hole, guide the roots down and spread them out around the little mound. (You don't want them wrapped around each other, because when they grow they'll choke each other off.) Check to see that the tree is standing straight.
- Now fill the hole with the same dirt you took out. Then lift the tree slightly as you press down the dirt with your hands or feet (lightly). You want the base of the tree to be just a little above the ground and the soil to be soft, rather than compressed. Do not add amended soil. This will weaken, rather than strengthen the tree, especially if it's a native one.
- Now measure three feet out from the tree (if it's a small one––further, if it's a big one), and dig a shallow trench in a big circle around the tree. Use the soil you dig out to build a wall (berm) on the outside to keep water inside the trench. Push any extra soil toward the tree to create a little hill that the tree sits upon.
- Once the berm is completed, you can fill the circular trench with water and let it sit until absorbed. Roots grow toward water, so as they sense it coming from the outside circle they'll grow in that direction, thereby creating a nice wide, stable root system. This is how you'll water from now on.
- Finish by mulching the area between the tree and the berm to prevent water from evaporating from the soil too quickly. Keep the mulch away from the tree trunk.
From now on you should water the tree about once a week, then once a month until the tree is established. As the berm wears away and the tree gets bigger, you'll want to build another berm further away from the tree. At some point, you might even want to replace the berm with a decorative stone wall.
After a year or so you shouldn't need to water the tree at all. By then the tree should also be benefitting your landscape.
Your Tree Planting Skills
Have you ever tried planting a tree?
How a Tree Helps Your Landscape
As your tree grows, you'll start to see the benefits of your local hillsides begin to apply to your own landscape as well. The crown of your tree will provide a home for songbirds you love to hear. Its flowers will provide beauty. Its fruits (including nuts) will provide food for animals and maybe humans. Its leaves will provide shade for your house and any sun-sensitive plants you position beneath them. Fallen leaves and twigs will provide material for your compost pile.
The trunk of the tree and its broader branches will provide a great place for kids, cats, and squirrels to climb. And the thicker branches are great for hanging swings or hammocks. The bark can be peeled off by kids curious about insects that live under it, providing an interesting learning opportunity. Interlacing roots will keep your garden soil absorbent, just as they do out in the wild.
Trees block wind, so if you have heavy winds in your area, it's a good idea to plant a variety of trees in a small grouping, so they hold each other up. And healthy trees cool the air. They counteract the "heat island effect" of sidewalks or asphalt roads in your neighborhood, making an otherwise hot area much more pleasant to live in.
One last recommendation. If your area is fire prone, as it is in Southern California, some native trees will have evolved to resist or survive fires exceptionally well. Look for them, since they can help protect your landscape from wildfires too.
If your area is prone to tornadoes or floods or any other kind of natural weather extreme, there will be trees and shrubs that have adapted to protect themselves better than most in that habitat. These can provide special boons to your landscape, if you plant them under the conditions they are used to.
Plant the tree's biome, as well, creating your own beautiful natural wilderness, and watch your tree and its attendant birds, insects, and wildlife thrive. Good luck and have fun!
This video shows the basic steps in planting a tree, as well as additional steps if your tree comes in a container. It's a good way to get an overview.
Additional helpful links:
- Sustainable Urban Landscapes | University of Minnesota Extension
Trees and turfgrass are commonly planted together in today's landscapes. However, they tend to be incompatible and interfere with one another, above ground and below.
- Tree Islands: Planting Around Your Lawn Tree
Lawns and trees don't mix very well. If you want the space under your tree to be planted, consider local ground covers or wild herbs.