3 Reasons to Plant in Containers

Containers can be stylish garden fixtures in their own right, irrespective of what they hold. Aesthetically, adding plants in pots adds another layer of interest and depth to the landscape with the varying heights they offer. Pots and containers offer many advantages over planting in the ground. They allow you to have a great amount of control over soil type, nutrients, and drainage. They can be portable, provide easy access, and rein in aggressive plants.  

Portable Perennials

Citrus trees can be grown in pots and brought inside when the weather cools.

The cold winters and hot, dry summers of the Inland Northwest really limit our available plant palette. Making your plants portable, however, can open up new possibilities. Growing non-hardy plants like citrus in pots allows you to bring them inside for the winter to protect them from freezing temperatures. Tender succulents, tropical plants, and other favorites from southern climates can be planted in containers and enjoyed outdoors during our warm months. After a summer outdoors, they can be transitioned to houseplants for the winter. Similarly, plants that are stressed by our long, hot, sunny summer days can be moved to more sheltered, shady locations at the peak of summer. For ultimate portability, choose lightweight plastic pots and a well-drained potting mix. If you love the look of ceramic and terra cotta pots, consider planting in a plastic insert for the best of both worlds.

Accessible Annuals

Canna lilies in a carved ceramic pot add a tropical flair to this lakeside landscape.

For annual plants that are only going to last one growing season, it can feel like a lot of work to get down and plant them in the ground for a few months’ beauty. Planting annuals in pots, however, can lessen that burden. Depending on the size of the pot, it can be lifted onto a counter or provide substantial height itself, making it easier on the body. Potting soil is also usually easier to work than native soils, which can be compacted or full of clay or rocks. It’s simple to customize soil conditions for specific plants, adjusting the nutrients, acidity, and organic matter in each container according to the plants’ needs. When the growing season is over, empty pots can be put away until spring rather than leaving bare swaths of dirt, or decorative containers can be left in place to serve as winter interest.

Reined-in Roots

Small trees like curly willow can be grown in containers to control their roots.

Most gardeners have had to deal with aggressive plants with spreading root systems and know the work involved in containing or eliminating them. Planting these troublesome species in containers can be a great solution to include them in your garden with less risk. Many plants in the mint family are well-known for their rhizomatic growth, so pots and planters are an excellent way to enjoy their aromatic foliage and flower spikes without running afoul of their root systems (they can, of course, still spread by seed). And if you simply must have extremely invasive species like bamboo or horsetail in your garden, containers are the only way to responsibly grow them.

It’s not just perennials that make good container plants, however. Small trees can be maintained in planters, both for visual interest and to prevent unwanted habits. Trees that sucker or invade sewer and irrigation lines, like willows, sumacs, or aspens, can be enjoyed in a planter instead. If you’re up to it, root pruning every couple years can help to ensure the vitality and longevity of your potted tree.

10 Steps to Successfully Plant a Tree

Trees are a great addition to any landscape. They raise property values, decrease respiratory diseases, lower cooling bills, reduce stormwater runoff, provide wildlife food and habitat—the list goes on and on. If you want to capture some of these benefits for yourself, there are ten steps to follow when planting a tree to ensure it will thrive and grow for years to come.

1. Locate Utilities

The last thing you want to do when planting a tree is accidentally damaging underground utilities. Call 811 before you do any digging to have your local providers come out to locate and mark any utilities on your property. Also consider overhead utilities—don’t plant a tree that will reach 40’ tall underneath your electrical service drop or other supply lines.

Dig a hole three times as wide as the tree's root ball and just deep enough for the trunk flare to sit at the finished surface of the soil.

2. Identify the Trunk Flare

The trunk flare is the point at which the tree trunk transitions to the root system. The trunk flare should sit right at the surface of the earth after the tree is planted. Burying a tree too deeply can suffocate the tree, create problems with fungus and pests, and lead to a poorly developed root system. Most species of trees have a clear curve leading to the roots, but for those without, the trunk flare should be considered to be the point above the highest root on the trunk. Trees from the nursery sometimes have their trunk flares buried too deep, so some excavation might be necessary.

3. Dig a Wide Hole

A tree’s roots travel outward much more than they do downward. Dig a hole three times as wide as the root ball, but only as deep as the bottom of the root ball to the trunk flare. After you backfill the hole, the roots will have wide ring of uncompacted soil to grow into.

4. Remove the Tree Container

Whether it’s a plastic pot, burlap, or wire mesh and plastic, remove any material containing the root ball. For very large balled and burlap trees, it may be difficult to remove the entire covering. In that case, cut the metal cage to remove the sides and remove as much burlap as possible. The roots will grow laterally and should not be constrained by the remaining material.

It is especially important, however, to remove any synthetic twine or burlap, as these materials will not degrade underground and will strangle the growing tree. Twine around the trunk can rapidly girdle the tree, cutting off its transport of water, air, and nutrients, and leading to the decline and death of the tree.

Container-grown trees may have circling roots or other root problems. Making few vertical slices and spreading out the roots as much as possible will help the roots grow naturally and vigorously.

5. Place the Tree in the Hole

After preparing the root ball, place the tree in the hole so that the trunk flare will sit a couple inches above ground level. It is better to have the root flare a bit too high than for it to be buried. This will also allow for some settling of the tree in the soil. Spread the roots out in the hole as much as possible.

6. Straighten the Tree

After the tree is settled in its hole, view the tree from several directions to make sure the trunk is straight and vertical. Add soil underneath the root ball to support the tree as necessary. For multi-stemmed trees, consider where the tree will be viewed from and focus on the overall balance of the branches from those points.

7. Fill the Hole

When the tree has been positioned well, start backfilling the hole gently, making sure not to damage the roots. To help settle the soil evenly, fill the hole a few inches at a time, soaking the soil with water as you go. This will eliminate air pockets in the soil, which can dry out roots and settle unexpectedly in the future.

8. Stake the Tree if Necessary

Not only do most trees do not need staking after they’re planted, it can be detrimental to their overall vigor. On windy sites, however, or if the tree is in a location that could see damage from lawnmowers or vandalism, protective staking may be warranted. If staking is considered necessary, make sure to remove the stakes within the first year of growth to avoid long-term damage to the tree.

Apply two to four inches of mulch around the tree, avoiding the trunk itself.

9. Mulch Around the Base

Mulch protects your tree in a variety of ways. It holds in moisture, reduces competition from weeds, moderates soil temperature, prevents damage from string trimmers or lawn mowers, and simply looks better than bare dirt. Adding two to four inches of mulch, whether it’s shredded bark, pine straw, compost, or any other organic material, will greatly improve the health of your new tree. Ensure that the mulch is kept a couple inches away from the trunk of the tree to prevent issues with rot or pests that could arise from the retained moisture.

10. Keep Providing Care

Putting the tree in the ground isn’t the end of the journey. Because of the disturbance to the root system, many newly-transplanted trees undergo transplant shock. The first few weeks after planting are an especially important time to nurture the tree. In the Spokane climate, regular watering will be the most important thing to do to protect your tree. A new tree needs approximately five gallons of water per week for every inch of trunk diameter, and a slow, deep watering with a drip system is much better than dumping a bucket of water around the tree and calling it a day.

Keep an eye out for pests and root suckers, but otherwise keep maintenance to a minimum. Pruning should be kept to a minimum for the first few years and performed only to establish the form of the tree. Similarly, fertilizer should be avoided unless soil tests show a serious nutrient deficiency, as the salts in them can interfere with a young tree’s ability to take in water. Hand-pull any weeds that appear around the tree to avoid inadvertently damaging it.

The older a tree gets, the better it can withstand drought, disease, and neglect. Putting in time now will allow you to reap the rewards of having a mature tree in your landscape.

Adapted from the International Society of Arboriculture tree planting guidelines: http://www.treesaregood.com/treeowner/plantingatree.aspx