Whether your garden is big or small, indoors or outdoors, there is something special about growing trees in containers. Large container plants have a stature and design value that can transform your garden unlike any other plant.
Planting trees in pots doesn’t differ much from potting up any other container, with a few exceptions to consider. It is also a little more labor-intensive (it took me an embarrassing three hours to finish potting up my magnolia trees), but it is well worth it.
Follow these 13 tips to perfectly pot up your new tree, ready for long-term growth.
Choose The Right Tree
Select smaller trees suitable for urban gardens and container planting.
Before you start planting, you need to know what you will plant. Being confined to a small container isn’t a natural state for most trees, particularly those with large root systems that like to spread out.
While you can technically plant any tree in a container, choosing the right tree is best if you want it to grow well long-term. Choosing a massive tree with tough roots will eventually lead to stunted growth (or lack of fruit if you’re growing fruit trees).
Start with shorter trees suitable for urban gardens you know will be happy in a container for several years. If you have a particular tree in mind, look for dwarf cultivars that won’t grow as tall as others. For example, if you want to plant magnolias, it’s best to stick to shorter trees with a compact mature height rather than those that are happiest at over 50 feet high.
If you’re planting indoors, you also need to consider lighting conditions. Trees grow slowly as they are and will grow even slower if the light is not optimal. Stick to trees happy in bright indirect light (like ficuses) rather than trees that need a full day of sun to thrive.
Choose The Right Container
Pick the right container initially, prioritizing drainage for tree health and growth.
Next, think about what will house your chosen tree. Trees aren’t as easy to repot as smaller plants and don’t need repotting as often. It’s far easier to choose the perfect container from the start than to worry about having to repot in a year.
The most important consideration – as I always say – is drainage. No matter how pretty a decorative container is, it won’t be suitable for your tree if it doesn’t have drainage holes. You can try to keep the roots dry and water carefully, but it will negatively affect growth in the long run.
Your container should also be large enough to accommodate root growth. Consider the tree’s mature size and pick a container that will provide space for growth without going so large that the balance is off. If you want the tree to stay small, restrict the container size slightly, but not so much that it will quickly become rootbound.
To boost drainage, choose a material that will wick water away from the soil, like terracotta or fabric bags. Also, consider longevity when choosing your pot, especially if you’re planting a large, established tree that won’t need repotting for a while.
Pick The Right Location Before You Plant
Consider the weight and placement of your containers before planting.
The regular considerations of choosing a location (sunlight, wind) also apply to your containers. But there is another element to choosing a location you don’t want to forget – weight.
Potted trees in massive containers are usually quite heavy. If the pot is deep and made from dense materials, it can be almost impossible to move without the help of a trolley or several people.
That’s why it’s best to pick your location before planting. Move the pots around to ensure you’re happy with the position before filling them with soil to make them easier to move. Only once you’re sure can you start planting.
If you’re planting indoors, this can be tough to follow. It’s usually better to plant outdoors and move indoors to limit mess. But if you plan to go this route, ensure you have someone nearby to help out and only water once the pot is inside (saturated soil is far heavier than dry soil).
Raise The Pot
Elevate your pot slightly to enhance drainage and airflow.
After choosing the location, consider raising the pot off the ground slightly if you’re using a fully enclosed pot. Although this tip is optional, it will go a long way to improving drainage, preventing the holes at the bottom from getting blocked, and improving airflow.
The easiest solution is to purchase pot feet for your container, designed to raise pots off the ground. But you can use anything that is level and able to handle the weight of the container when the soil is wet.
For indoor trees, simplify your watering by adding a drip tray alongside your pot feet. This will catch any excess water that drains from the bottom, keeping your floor dry and limiting any need to move your pots back and forth to water.
Fill The Base
Consider filling the base with materials like empty bottles to lighten a tall container.
If you’ve chosen a very tall container, want to make the pot lighter, or save money on potting soil, you can fill the pot’s base with other materials before you fill it with soil.
Gardeners often recommend filling the base of pots with crocks or stones to stop soil from spilling out. But I’ve found that isn’t always necessary and can actually block drainage holes if you place them incorrectly. The exception is smaller plastic pots in windy areas. Placing stones at the bottom can help weigh down the container to prevent it from toppling over.
You can try a few other hacks for more shallow-rooted trees that won’t grow too deeply into tall containers. To take up space without weighing the pot down, fill the base with empty bottles or cut up pool noodles. Just ensure there is still enough soil above this layer to allow the roots to expand.
Pick The Right Soil
Add compost or perlite for better drainage and moisture retention.
Soil directly impacts root growth, influencing the health and growth of the entire tree. That’s why it’s vital to get soil choice right from the start, avoiding any issues with structure or growth down the line.
Avoid using only soil from your garden to pot up any trees. Garden soil is usually too dense for container plants and can carry weed seeds or, worse, pests and diseases to the container. Instead, look for high-quality potting soil with ingredients that retain moisture and drain well.
I also like to mix equal amounts of compost into the potting soil before planting. This isn’t 100% necessary, depending on the potting soil you’re using, but it does boost moisture retention and organic matter in the soil, improving structure.
As the soil dries out slower indoors than outdoors, indoor trees have slightly different requirements. Add a few handfuls of perlite or bark to your soil mix to boost drainage before planting. This will help prevent issues with root rot that can ultimately kill your tree if not controlled.
Mix In Slow-Release Fertilizer
Enhance tree growth with a slow-release fertilizer in the soil mix.
To give your trees an extra nutrient boost as they start, mix in some balanced slow-release fertilizer as you mix your soil. This is another optional step (especially if your chosen potting mix already has fertilizer mixed in), but it helps give your tree a better start.
It’s important not to overdo it on the fertilizer. Too much can end up harming growth rather than helping it by damaging the roots. Only use the amount recommended on the packaging and never more.
Slow-release fertilizers are designed to break down over time as you water, slowly adding nutrients to the soil. That means you won’t need to fertilize for several weeks or even months. Don’t use other fertilizers soon after planting, as this can burn the roots or cause a nutrient imbalance.
Lay Down Newspaper
Minimize cleanup by laying down newspaper before planting to catch spills and soil.
This tip applies to my fellow houseplant lovers who only have space to plant indoors. Even if you’re incredibly careful, some mess when planting a new tree is inevitable. Save yourself some cleaning time (particularly if you have carpets) by laying down newspaper before you start.
If you’re potting up a large tree, the easiest way to get it out of the pot or bag is to lay the tree on its side. If you do this on the floor on a sheet of newspaper, wrap that up after planting and throw it away or toss the soil outside. Also, invest in a big bucket to mix your soil to limit any spilling on the floor.
Tease The Roots
Loosen tangled roots gently before planting to encourage outward growth.
Once you pull the tree out of its current container or bag, you’ll probably see the roots wrapped around each other or taking the shape of the container at the bottom. If you plant your tree as is, these roots will likely continue to grow circularly around each other rather than deeper into the container, eventually stunting growth.
Loosen any tight roots with your fingers before you lower the tree into the pot. Pay attention to the roots on the sides as well as the bottom. This will allow them to grow outwards into the soil after planting.
Loosening the roots can be tough if the roots are very tight and the soil is dry. Don’t worry if some break off. While you should be as gentle as you can, a few broken roots won’t negatively affect the growth of the tree. They will appreciate some freedom to move.
Don’t Plant Too Deeply
When transplanting to a deep container, ensure the soil line matches the previous planting.
If you have a deep container, don’t make the mistake of placing the tree at the bottom and filling the gaps with soil. The soil line should remain the same in the previous container as in the new one, with all the excess soil sitting below the root ball.
If you plant your tree too deeply, you risk damaging the central trunk and causing rot. Since this structure is responsible for transporting water and nutrients to parts of the plant that need it, rot can be detrimental to overall health.
Fill the pot with soil so the soil line sits just below the pot’s rim. You should cover the top with a light layer of soil, but not so much that the stem is buried. The extra gap below the rim will stop any excess soil from spilling out when watering.
Stake If Needed
Install a stake close to the root ball to support young trees in windy conditions.
Young trees with weaker trunks may have trouble keeping themselves upright as they establish. This is even tougher when placed outdoors in windy conditions. Install a stake at planting time to help anchor your tree without growing askew or disturbing the roots.
Bury the stake into the close to the root ball, sitting upright. Then, tie the trunk to the stake so the tree sits upright, too. Use soft ties that will move as the tree grows rather than stiff ties that may cut into the trunk later.
After planting, firm the soil around the tree and water immediately to encourage root growth.
Press down around the tree’s base as soon as you’ve planted to firm it in place and remove any air pockets. Then, water immediately to saturate the roots and encourage the roots to grow deeper into the soil.
Exposure to the air is not something roots are used to (or particularly like). Watering soon after this exposure will limit issues with transplant shock that can slow growth. Water slowly and deeply to ensure all parts of the soil are saturated. Also, check the drainage holes at the bottom to ensure the soil drains quickly enough.
Since this is your first watering, you may need to do a few rounds to cover every inch of soil. Fill up the top and allow that water to absorb into the soil before filling again. After three or four times, you should see water starting to drip out the drainage holes.
Mulch helps retain soil moisture, especially in sunny areas or darker containers.
The final tip applies more to outdoor trees than indoor ones. If you’ve placed your tree in a full-sun area, the soil will dry out quickly throughout the day. If you have a darker-colored container, it will dry out even quicker.
One way to combat soil dryness and reduce your need for water is mulch. Apply a thick layer of mulch to the top of the soil, avoiding touching the stem. This mulch layer will keep water in the soil longer while regulating the soil temperature. Choose an organic mulch that will break down over time, improving soil health.
Potted trees have undeniable ornamental value both indoors and out. Follow these tips to pot up your tree perfectly, ensuring healthy growth for years.