If you are anything like me, you’ve spent loads of money on cute planters only to find out that they were wrong for the plants you bought them for. Here are some guidelines for choosing the perfect pot for your flowers.
Every container needs drainage holes.
Most pots you can buy at your local nursery already have holes drilled into them, but there are some that don’t. When that happens you need to drill them yourself. I like to use a ⅞” drill bit for larger size holes. If water doesn’t drain out properly then the roots can rot sitting in all that water.
Each container material has a specific porosity.
How porous the pot is tells you how well it holds water, which we will get to in a moment. Bottom line, what your container is made of matters.
Generally, planters and containers are made from these materials:
Terra-cotta
Unglazed clay
Wood
Unsealed Concrete
Fabric
Glazed clay
Metal
Plastic
Molded fiberglass
Sealed concrete
Terra-cotta, unglazed clay, unsealed concrete, fabric, and wood are porous materials that allow water to seep through the walls. This can be very helpful if you live in a wet climate since the porous material will help water drain out. These pots can also be used for drought-tolerant plants who don’t love their roots sitting in damp soil for an extended period of time.
Glazed clay, metal, plastic, sealed concrete, and molded fiberglass hold water in since they aren’t porous. Plants who like to drink and gardens in hotter climates are perfect for containers that are non-porous.
I did not understand the importance of porosity when I first started out with container gardening, and since terra-cotta had the right “look” for what I first wanted to do, I bought four terra-cotta containers and placed some viola and pansies in each one. I’d seen pictures in gardening books of such a setup and wanted to emulate it.
The problem was I lived in Southern California and not wet England. Many of my favorite gardens are located in England and the climate couldn’t be more different than the one I live in. Unfortunately for me, terra-cotta wicked the water away from my thirsty plants. I couldn’t water them enough and they died. The next year, I switched my pots out to faux terra-cotta, made out of plastic, and my plants were much happier.
The size of your container will depend on your plant's growth habit.
You’ve all heard the adage that size doesn’t matter but, in this instance, the size of the mature plant matters greatly.
If the growth pattern of the plant indicates it will be large, you need to get a container that is on the larger side. The rule of thumb is to get a container that is 2”-4” wider and deeper than the nursery container you bought it in. If the container is too small, the plant will eventually become root bound, i.e. the roots will circle the inside of the container and become tangled with no more room to grow, and the container can tip over.
Conversely, you can’t put a small plant in a too-large container thinking it will want the extra room for its roots, especially if it will not grow to a big size. In this instance, the larger container will hold the water longer since there is so much more soil, and your plants’ roots can rot.
Roses are a perfect example of this size requirement. When you first get own root roses, they tend to be first year plants and are tiny. I put them in 3 gallon pots for the first year. In their second year, they've been moved up to 7 gallon pots that are super deep so their roots can stretch down. In the third year I will take them up to 10 gallons for more room.
You must take into account your climate when buying pots.
All of the containers made of porous materials have a tendency to expand when temperatures go below freezing. This expansion can cause cracks. The recommendation is to take the pots inside your garage or your home when the temperature gets that cold. This seems like a lot of trouble and back-breaking work to me, so consider this when shopping for containers. Personally, I’d stick with the non-porous materials in climates that get a lot of snow.
The weight of your container matters.
Especially if you’re anything like me and are constantly moving pots around. A lot of my architecture friends love the aesthetic of concrete planters but they are so heavy that once you get the soil, fertilizer, and plants in there you won’t be able to move it anywhere else. That’s a big problem for me in my tiny garden. And in hot climates like mine, concrete can heat up and bake the roots. No thank you for that.
Taking all the above into consideration, all of my pots are plastic and fabric for my Los Angeles tiny garden. The plastic does heat up in the summer, but my plants get plenty of water to make up for that. I’m playing around with the idea of introducing terra-cotta back into my garden for the salvias I have planted since they are drought tolerant and don’t like having their feet wet. The one downside is I do have to change out the plastic pots every 2-3 years because they eventually crack from the constant heat and UV light. But they are cost-effective, so this works for me. And since they are so lightweight, I can upcycle them or use them elsewhere in the garden.