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Container gardening is a great solution for those of us in apartments, rented homes, and small spaces.
Even for those with larger gardens, it creates an opportunity for additional plants on the porch or other space where gardening would be difficult, year-round indoor gardening, and keeping certain overly enthusiastic plants like mints from taking over your yard.
But picking the right planter or container can be challenging. Different plants have different needs, and many options exist, both in stores and online.
So how can you choose the right planter? Read on to find out.
Factors to Consider
There are 7 main factors to consider when determining the correct planter size – size, material, drainage, source, purpose, lifespan, and location. Let's look at these more closely.
Jump to a factor: Size | Material | Drainage | Source | Purpose | Lifespan | Location
1. Size
The depth of your container is vitally important. We include container size in each of our gardening facts articles such as these for the minimum container sizes of lettuce and carrots, and we always include the depth.
If a container is not deep enough, the plant's roots will not have room to grow. This can lead to a root-bound plant, stunted or severely slowed growth, lack of fruiting, much higher watering demands, and even plant death.
If you cannot find information about the appropriate container depth for a plant, the best formula is to determine the plant's maximum root length and add 1 inch. So a plant with an 9-inch root would need a container that is a minimum of 10 inches deep.
Some plants have a long, skinny taproot (or even multiple long, skinny roots) with the ability to wrap around, so they may tolerate a shallower container, especially if it is wide. But many plants experience negative symptoms if they run out of room or even get too close to the edge of the planter, and their roots do not wrap around. So it is best not to expect the plant to be fine in a smaller-than-appropriate container.
Some plants have the capacity to adapt to the size of their container such as peppermint and other mint family members like lavender. Peppermint roots can be anywhere from 2 inches to 2 feet deep, depending on age, growing conditions, and size of the container or other growing space. This is why the minimum container depth is only 4 inches, although using a larger container will result in a larger peppermint plant. Some gardeners have even had success with a mint bathtub!
For certain plants, the container also needs to be a certain width. Some examples of this are strawberries, cauliflower, and aloe vera. These plants need space to spread out and sit on the soil. Otherwise they will become cramped, which may result in a stressed plant, smaller produce, and lower production.
If a plant requires a certain container width, we include that in our minimum container size recommendation in its gardening facts article as well.
Most container size recommendations are based on planting 1 individual plant unless stated otherwise. (For example, in the container size for onions section, we mention that a 5-gallon planter can hold 6-8 onions.) If you are planting multiple plants, be sure to allow enough depth and width to do so. Consult your seed packet for spacing information.
When deciding what size planter to use, be sure to include any companion plants in your calculations.
For example, if you are growing lettuce and carrots together, you would go with the recommended container depth for the carrots, not the lettuce. Most lettuces have very thin, fairly shallow roots. So as long as you have allowed enough space between plants for each carrot and lettuce plant to spread out sufficiently, lettuce's roots do not really factor into the equation.
On the other hand, if you are planting kale and leeks together, you may notice that while both of these plants can tolerate an 8-inch container, kale prefers 12 inches or more. It is less productive in a smaller container, even though an 8-to-11-inch planter does not harm the plant. Knowing this, you may want to opt for a minimum of 12 inches. Even better, since you know these plants have longer roots, you may consider an even deeper container or one that has a higher total capacity like a 5- or 10-gallon planter.
Finally, be sure to measure the size of the space where your planter will sit before you decide on the size of your planter and what you will plant in it. If your windowsill is only 3 inches wide, you don't want a planter that is 5 inches wide unless you have a creative workaround or want to find a new spot for it! The same applies to porches, low spots, and most other places that would house a planter.
2. Material
The main materials used in traditional planters are ceramic, plastic, glass, and metal.
Ceramic planters are made of clay. They include terracotta, stoneware, porcelain, and others. Ceramic planters have a long history of use, and most ceramics are unlikely to leach harmful substances into your soil. On the other hand, they tend to be heavier and more expensive.
Plastic containers are accessible and affordable. Most are lightweight as well. Ready-to-use plastic planters can be found at major retailers like Target and Amazon. There are also several DIY options such as yogurt containers, milk jugs, buckets, and more.
The main concern with planting produce and herbs in plastic planters is the risk of harmful substances leaching into your soil and, in turn, your food. When selecting a plastic planter, be sure to choose a food-grade plastic – Plastic #2, #4, or #5. All other plastics are prone to leaching BPA, styrene, and/or other substances, depending on the number.
Glass planters are leach-free options that are visually appealing. They make it easy to monitor the state of your soil and your plant's roots. Like ceramic planters, they tend to be heavier. Unfortunately, hardly any glass planters have drainage holes, so you will need to make them yourself.
Metal containers are another reasonable option, although there are concerns about harmful leaching with metal containers as well. If you are using an antique metal planter, be sure it does not have lead paint.
3. Drainage
Adequate drainage is required for any planter. If a planter does not have enough drainage, when you water your plants, the water will stay in the planter. This will cause your plant's roots to be waterlogged, which can lead to poor plant health.
As mentioned above, most glass containers do not have drainage holes. Some metal and ceramic planters also do not have drainage holes. Although most plastic planters have at least 1 drainage hole, they do not always have enough holes or large enough holes.
If your planter does not have sufficient drainage, you will need to create it. Here are the 2 ways I have used in the past:
- Drill holes in the bottom of the container. I use this drill myself.
- Hammer a nail into the bottom of the container and then remove the nail once it has made a hole. Repeat this a few times in different places until you have enough holes. I used this method during my first year of gardening since I was using mostly store-bought planters and didn't have my drill yet.
With either of these methods, watch carefully to make sure your planter material does not crack. If the crack is deep enough that soil can fall out, that can create a different problem altogether!
4. Source
The next factor is the source, or where your planter comes from.
Many nurseries stock planters, though they may have a smaller selection and are often more expensive than other source. Of course, this varies by nursery.
Many national and regional retail chains sell planters as well. In my experience, this is usually the most economical option. Here are a few places I have found them in the past:
- Target
- Fred Meyer
- Walmart
- Home Depot
- Lowe's
Finally, some online retailers like Amazon also stock planters, many of them year-round. This is an advantage over nurseries and in-store retail, most of which only sell them seasonally.
So, for example, you could get these 7.5-inch-deep windowsill planters in November and grow peppermint, lettuce, thyme, spinach, and more all winter long!
If you have the skills and equipment, you can make your own ceramic planters. Just be sure to create drainage holes, as described in the Drainage section above.
5. Purpose
Your selection also depends on the purpose your container will serve. Here are a few questions to ask yourself:
Will this be used for seed starting?
If so, most likely, you will want to use a much shallower container than you would if you were either direct-sowing the seeds or transplanting an existing plant. I personally use either a covered egg carton or seed-starting trays. Burpee has a range of tray sizes like these 16-cell trays and these 72-cell trays that have been used and loved by gardeners for decades.
Will I be transplanting or repotting my plant later, or will it stay in this container?
If you plan to transplant or repot your plant in the future, you may be able to use a smaller pot initially. For example, as noted in the Size section, most mints survive in 4-inch-deep containers without an issue, but they will eventually become root-bound. Although they may not die when they become root-bound like other plants do, the mint plant will remain a small plant. On the other hand, if you eventually transplant the mint to a 10-inch container, it will grow much larger, especially if the new container is also wider.
Another example would be fruit trees such as cherry trees. Because mature cherry trees' roots spread about 40 feet in all directions, we do not recommend them for container gardeners in general. See the Container Size section of the Growing Cherries article here. But it takes time for them to grow that large. A 5-gallon bucket may suffice for a first-year plant, and a 15-gallon planter may be sufficient for a second-year plant. This knowledge can come in handy if you are waiting to move to a new piece of land or waiting to clear a space for your young cherry tree or other fruit tree.
Will this be an indoor or outdoor planter?
Although most planters can handle either one, outdoor planters will face harsher conditions like hotter and more direct sun, stronger wind, more water, and more. This makes it especially important to choose a sturdy planter for outdoor plants, while you may be able to get away with a thinner or more fragile planter for indoor plants.
Will this planter stay in one place, or will it be moved?
Maybe you are trying your hand at overwintering tomatoes or calendula indoors. Maybe you move your planters around your yard based on the sunlight at different times of the day or other conditions. Maybe you are planning to move homes during the growing season.
Whatever the case, if you plan to move your planter, be sure to take the weight into consideration. Do not make the planter too heavy to carry. This may mean choosing a lighter material like plastic or a light metal. It may also affect the size of the planter and, therefore, the plants that you grow.
When deciding about the weight and movability of a planter, it is best to assume that the plant and its container will be holding some water by the time you move them. Although you should ensure that your soil is well-draining, it will almost always hold on to a little of the water, and your plant's roots may swell and hold onto some water as well.
These are not issues if your planter will stay in one place. If you are concerned about the appearance of your planter though, be aware that staying in one place means that the sun will beat down on the same part of the planter, day after day, and this may cause fading or discoloration.
6. Lifespan
Lifespan, or how long the plant will live, is also a factor in container selection. Consider whether the plants in the container are annual, biennial, or perennial and, if perennial, how many years they are expected to live.
Lifespan can influence other factors mentioned here such as the material, location, and size of the planter, among other things.
7. Location
We touched on this earlier in the Purpose section, but whether your planter will be indoors or outdoors should inform your choice about the material and weight of the container. There are many types of locations within those 2 categories though.
For example, you may want your indoor planter to be, more specifically, on the windowsill. So you would choose a windowsill planter like the one I mentioned earlier. (Here it is again in case you missed it.)
But most windowsill planters are not deeper than 7 inches or so, as taller planters could become top-heavy and fall over. So if you want to grow a plant that needs 5 gallons of space like marshmallow or cauliflower, you would not have them on a windowsill.
Be sure that your plants get enough sun. Indoors, this means that they should be as close to a window as possible or that you should use a grow light. In some cases, you may need both a grow light and a window, especially if the window is north- or northeast-facing or if you are growing during the winter in a northern latitude like Maine, Minnesota, or the Pacific Northwest. These are the grow lights I use, and I have been very happy with them.
Outdoors, it means being sure to place your planter in the correct sun condition for the plant(s) inside it. For example, in most areas, bell peppers need to be in full sun, and chard needs to be in part shade to full shade conditions. Be sure to take anticipated rain, wind, and other conditions into consideration as well as any known regional variations.
As noted in the Size section, be sure that the container and the place it will sit on have compatible sizes.
And that about wraps it up! Just to review, when choosing a planter for your container garden, be sure to consider all the factors:
Feel free to revisit this article anytime you need to, pin it for later, and get the free printable summary via email below! Happy growing!
Read More
Check out these articles about plants that are commonly grown in containers:
- Growing Basil: Quick Facts
- Growing Chamomile: Quick Facts
- Growing Cucumbers: Quick Facts
- Growing Green Beans: Quick Facts
- Growing Lemon Balm: Quick Facts
- Growing Lettuce: Quick Facts
- Growing Mizuna: Quick Facts
- Growing Oregano: Quick Facts
- Growing Peppermint: Quick Facts
- Growing Strawberries: Quick Facts
- Growing Spinach: Quick Facts
- Growing Tomatoes: Quick Facts