Growing Trees In Containers
Planting trees in containers is becoming more popular, especially in landscapes with little or no outside space. You don’t need a large piece of property to grow a tree. If you have a porch, patio, or balcony, you can grow a tree in large container. Container-grown trees can be used to frame entryways or to provide interesting focal points. They are well suited to small spaces in the landscape such as patios and decks and can be used alongside other container-grown plantings as well.
Choosing a Container for Your Tree
Trees can be planted in regular, moveable containers as well as in large, permanent planters. Containers and planters for landscape trees are available in numerous styles, shapes, and colors. Containers should always complement their surroundings as well as the trees that are placed in them. The container should be large enough to accommodate the tree. Therefore, the mature size of the tree should be considered in order to choose a container with adequate space to accommodate both the growing tree and its roots. Containers should also be as wide as they are high in order to provide the best possible insulation to the roots.
The overall weight of a container is important too, and this should be taken into consideration as well. Not only is the weight of the container itself a factor, but take into account how much weight the soil, tree, and water will add to it, especially if the container will be used in areas such as balconies or rooftops, where structural weight capacity may be an issue.
- Clay pots are heavier than plastic, but are more stable in windy conditions, especially with larger trees.
- Terracotta pots provide weight for stability but should be frost resistant.
- Lightweight plastic pots are ideal if plants require moving or if they are located on balconies.
- Larger, heavier containers or planters can be used for trees that will remain as permanent fixtures year round.
Drainage is another important factor when choosing a container. Always check the bottoms of containers to ensure that there are ample drainage holes for excess water.
Using the Right Soil for Your Container Tree
Soil is very important to the health of trees. The soil should maintain sufficient aeration and drainage while retaining suitable amounts of moisture. Good container soil retains adequate levels of water without becoming waterlogged. Do not use soil directly from the garden or surrounding landscape. Regular soil may not drain well in containers and could be more prone to weeds, insects, and diseases. Instead, use soil-based compost. This is widely available at nurseries and garden supply centers, or you can make your own using premium potting soil and amending it with compost, sand, and perlite.
Caring for a container-grown tree is different from a tree growing in the landscape. They are more prone to drying out; therefore, container-grown trees need regular and thorough watering. Container-grown trees should be supplemented annually with slow-release fertilizer or use a liquid feed at regular intervals. Refresh the soil each spring by removing the loose, dry topsoil and replacing it with fresh, compost-enriched soil.
Tree roots in containers may also die during summer if the soil temperature becomes too hot, exceeding air temperatures. The heat from pavement can quickly cause the soil in containers to become excessively hot, burning the roots and drying out the soil. Windy conditions can also dry out container-grown trees. Therefore, containers should be placed in a sheltered location to protect the trees from extreme temperatures and wind.
Selecting a Tree to Grow in a Container
The greatest challenge in selecting trees for containers is in choosing those that are hardy enough to withstand extremes in temperature and can establish roots in a limited amount of soil. Temperature is one of the major determining factors. When trees are in the ground, the soil actually shields them from extremely cold temperatures. Tree roots are less cold hardy than the rest of the tree. As a result, the roots of trees that are planted in containers may die when temperatures drop below freezing. When the soil freezes, the roots cannot absorb water.
Choosing a suitable tree for a potted environment varies depending on its overall size, growing requirements, and location. Naturally, if the mature size of a tree falls on the small side, it is better suited for container growing. Smaller species and dwarf varieties are good candidates for containers. Trees that will remain situated in permanent locations should be chosen for their year-round appearance, size, and maintenance requirements.
Evergreens and nearly any other dwarf conifer can be grown in containers. Good choices include:
Deciduous trees like Japanese maple, star magnolia, river birch, crepe myrtle, and many types of fruit trees also do well in containers.
Maintaining the Size of Your Container Tree
Trees should also be compatible to their container as well as their surroundings. Since the size of a tree is usually proportional to the size of its root system, containers, in most cases, will restrict its ultimate size. However, if a tree does begin to outgrow its container, there are options.
You can prune the roots back and replant it into the same container or transplant it in another location. Root pruning is a similar technique to bonsai and will help to keep the tree small. Remove the tree from its container, tease out and trim the roots, and then repot.
Rather than having to resort to the intense task of root pruning, you should consider transplanting the tree to a larger container or if space permits, within the landscape. Tender evergreen or citrus trees should be moved indoors for overwintering. Protect the tree roots from winter cold by keeping the container in a protected area or use an insulating material specifically designed for containers during the coldest months.
Planting trees in containers is becoming more popular, especially in landscapes with little or no outside space. Find tips for growing trees in containers with information found in this article.
The Basics of Growing Trees and Shrubs in Pots
Whether you are limited on space, growing plants that don’t usually survive your local weather or just looking to create focal points, container trees and shrubs can be a lovely addition to your landscape. There are some considerations that you will need to remember to help them stay happy and healthy.
Research to Determine What Trees and Shrubs Are Best
One big mistake that some gardeners make is falling in love with a plant online or at a nursery and whisking it home with nary a thought as to whether it will work in your garden. This is especially true when you are trying to place a tree or shrub in a container. The cute little sapling that you spied at the garden center can turn into a tree that is over 100 feet tall.
The basics that you should check out for potential candidates include:
- Preferred hardiness zones
- Height and width at maturity
- Light and water requirements
- Potential for litter
Use Dwarf Cultivars as Available
You are asking a lot of a tree or shrub when you place it into a container. The roots have far less space to work with and can naturally become crowded. When you choose dwarf cultivars and species that are naturally on the smaller size, it is easier for them to adapt to the limited area presented. This is especially important when you are working with fruit trees since they will need extra energy to produce fruit and you want a good root base.
Choose Your Pot Size Carefully
Picking the right size of the container for your tree or shrub can be a bit tricky at first. You do not want one that is too small, of course, as this will leave little room for root growth and it is likely to become rootbound and struggle or die. Since it is a large plant, you might naturally think to place it in a very large container so it will have room even when it is fully grown.
You can run into problems if the pot is too large for the plant’s current size. When soil present is abundant and not enough roots to take up the water, it can retain moisture for too long and cause root rots that can ultimately kill the plant.
For best results, plan on moving up in 2” increments every couple of years until it reaches maturity. Repot sooner if you notice roots escaping from the drainage holes. If it is rootbound when you change containers, perform root pruning by using a box cutter or other sharp instrument to score along the sides of the root ball and remove the mass of roots. This will stimulate new root growth and keep the plant healthier.
Drainage is Essential
Even if you have the correct size of the container, you can run into root rot and other problems if there are not enough drainage openings present. Check your pot and use a drill to create more as needed.
Protect the Roots in Freezing Weather
Many trees and shrubs have adapted for survival through the harsh conditions present during winter. Growth slows, and the plant goes into dormancy. The roots are protected by the ground surrounding them, and the temperatures are at least a little higher than in the air.
In a container, there is a lot less buffer present for the roots. It is much easier for the soil to freeze completely and cause damage. Options are to bring the plant inside, bury it in the ground or place it somewhere like a garage or basement. If you choose to bury them, add mulch on top for extra protection and leave a space around the trunk to prevent insect and disease damage.
Don’t Forget to Harden Off Your Plants
If you are trying to grow plants in containers so that you can bring them inside when the temperatures drop, take it slow when you reintroduce them to the outdoors in the following spring. This process is called hardening off and is an essential step in protecting your trees and shrubs from harm.
Imagine that you are used to sitting quietly on a couch while listening to classical music. One day you are drifting off into a nap, but suddenly are jolted awake as someone throws you into the front row of a rock concert. This is the sort of experience that a plant will be subjected to if you do not harden it off first and let it adjust. Outdoor conditions are harsher than indoors since the light is magnitudes brighter, environmental conditions like drought, salt and wind are present, and insects or diseases are more likely to strike.
Instead, start by carting your plant outside for an hour or so for a couple of days. Gradually increase the length of time it stays outside over two weeks. After that, it is ready to spend the growing season in your landscape.
The basics of how to grow trees and shrubs in pots, so if you move, you can take your garden wherever you want.