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Whether you're growing them inside or out, potted plants add a great deal of visual appeal to your space. In order to keep them looking as beautiful as they did on the day you brought them home, you need to make sure you're meeting all of their needs. This includes understanding which size planter they need to thrive—as well knowing when they need to be repotted into something larger. Here, Tonya Barnett of FRESHCUTKY Cut Flower & Vegetable Garden, shares how to determine a plant's ideal pot size—plus, how to know when it's time to size up.
Consider the Roots
The reason why many varieties need larger pots has more to do with what's going on under the dirt, as opposed to above it. "Though different types of plants will have varying preferences in terms of pot size and needed space for the development of new roots, most grow well when pots are at least two inches larger in diameter than the plant," explains Barnett. "This allows ample room for growth to continue as the plant matures and becomes more established."
To ensure you've sized your pot correctly, you first need to know how to measure it; planters come in different shapes, and, therefore, are measured in different ways. "Round planters are most commonly sold by diameter, which refers to the distance measured across the top of the pot," Barnett says. "Though pots may have the same diameter, this does not necessarily mean that they are the same size." Pots which are measured in trade gallons, for example, will refer to the volume of soil which can be held.
Though sizing up is more common, you may find yourself looking for a smaller container if you have "overpotted" the plant, or transplanted it into a vessel that is too large. "Size selection of planting pots correlates directly to aeration and moisture within the planter," explains Barnett. Some of the risks you run into with overpotting is that larger containers can stay excessively wet for longer durations of time, causing root rot, yellow leaves, and even plant death. "To combat this issue, consider carefully downsizing into a smaller, more appropriately sized planter," she explains.
Almost all plants will need to be repotted at some point in their life cycle, so you'll want to familiarize yourself with the signs. "Growers may begin to notice that plants need to be watered much more frequently," she says. Also, if you check the drainage holes of your existing pot and notice roots are growing out of them, it's time to up-size. "How frequently plants need to be repotted will depend on the plant type, growth rate, and size," notes Barnett, adding that, in general, most plants will need to be transplanted into a new container once every two years.
For the best results, repot your plants in the springtime and move them into a container that is roughly two inches larger than their current one. "Make certain the container has ample drainage, and fill it with a high-quality potting soil," says Barnett. "Remove the plant from the old pot and gently loosen its roots before placing it into the new container." Once your plant is situated, she recommends covering the root ball with soil and watering it well.