Every plant parent wants their new plant to thrive. How can a container make a difference? What factors should you consider when choosing a pot? Why does the container materials matter?
We presented all of these questions and more to Amanda Lander.
Amanda is an enthusiastic gardener with experience gardening in two very different climates. She has a passion for all things green and growing, especially native plants and their many uses. She tries and tests all she learns and loves to share that practical, proven knowledge with others
Amanda, why does pot size matter?
The size of your pot matters mainly because of something called the perched water table. This is the level at which the soil’s ability to suck water upward matches the downward pull of gravity.
Different types of plants have different water requirements. The perched water table affects our ability as gardeners to meet those specific needs successfully. Choosing a pot of the right size decreases the chances of root rot or binding and allows for the efficient use of nutrients.
Why is it bad to use a pot that’s too big?
It’s a bad idea to use a pot that’s too big because plants require a balanced air-to-water ratio for healthy growth. If there is too much empty soil in a pot, it can take too long to dry out after watering, increasing the risk of root rot. If underwatered, the excessive amount of soil will remain too dry.
Extra space at the surface of an oversized pot can become infested with weeds, fungus, or pests and is unattractive. An unnecessarily large container can take up valuable space in the garden and disturb its visual appeal.
Should I consider root size?
You should consider root size when choosing a pot because the roots directly affect plant health. A pot that is too small will cause a plant to go root-bound which will stunt growth. Some plants have long taproots that require a taller pot than those with more shallow surface roots.
Ideal Pot Sizes for Your Plants
Choosing a pot the correct size for your specific plant may seem like a complicated science, but it doesn’t need to be. Consider the examples below to get a feel for the best ways to use pots of different sizes.
What plants are best for 10 inch pots?
A 10 inch pot is best for small fruits and herbs or up to 3 annuals. Examples include:
- Strawberries
- Parsley
- Mint
- Marigolds
- Zinnias
- Gerbera Daisies
What plants are best for 14 inch pots?
Consider large herbs, leafy vegetables, or 3-4 annuals when choosing a 14 inch pot. Examples include:
- Pea plants
- Bush beans (small varieties)
- Lavender
- Rosemary
- Spinach
- Leaf lettuce
- Dahlias
What plants are best for 18 inch pots?
An 18 inch pot is best for a miniature garden containing a mix of herbs or annuals, a large vegetable, or a small fruit tree. Examples include:
- Broccoli
- Tomato plant
- Blueberry bush
- Dwarf citrus tree
- Rhododendron
What plants are best for 24 inch pots?
24 inch pots are ideal for evergreen shrubs, dwarf trees, and sprawling vegetables. Examples include:
- Cucumber
- Squash
- Hydrangea
- Blue Pacific Juniper
- Dwarf Peach tree
What plants are best for 30 inch pots?
A 30 inch pot is a good choice for large plants and small trees. There is usually little danger of a planter this size being knocked over if kept outside, even in windy locations. Examples of plants to keep in 30 inch pots include:
- Rhubarb
- Pumpkin
- Plum tree
- Ficus
How can I choose the right drainage for my plant?
To choose the right drainage for your plant, read the tag or search the internet to learn its water requirements. Try to mimic the natural environment of each plant.
For instance, try out this pot for a prayer plant which retains water to maintain moist but not soggy soil. This pot for a fiddle leaf fig provides ample drainage so the soil dries out between soakings as it would in its natural habitat. The best pot for a spider plant retains sufficient moisture but drains excess water.
How should I choose the planter shape?
You should choose the planter shape based on your plant’s needs and location. Remember the perched water table when choosing a pot for your specific plants. For example, ferns will thrive in shorter pots where the perched water table keeps the soil evenly moist, but cacti will fare better in tall pots that dry out more quickly.
Planters that will be kept outside need to be stable. Pots with a rounded or tapered bottom are easy to knock or blow over.
Should I use square or rectangular pots?
Choosing a square pot for new starts can reduce the likelihood of circling roots and increase the success of transplants. Watering square pots in a group is more efficient than watering round pots because less water is lost between pot edges. Groups of plants can use the available nutrients in a rectangular planter more efficiently than a round one.
The real benefit of square or rectangular planters is decor-related. They can conform to a modern or minimalist aesthetic both indoors and outdoors. You need not feel limited though, as this shape is very versatile.
Pots with straight edges are easier to arrange in tight spaces. You can line them up to form rows or hedges. Because they have a defined front and back, plant groupings can be arranged attractively.
How should I choose the planter material?
You need to consider the location, size, looks, and the plant (or plants) it will contain when choosing the material of a pot. Just like patio versus bedroom furniture, different materials are better suited for outdoor or indoor use. Use the lists below to help you decide which pot material will be best for the needs and location of your new plant.
Ceramic / Glazed Pots
- Many attractive designs
- Retain moisture well
- Usually only one drainage hole
- Retain heat- can damage sensitive plants but benefits others
- Chip easily
- Prone to cracking when soil freezes
- Heavy
Plastic Pots
- Usually inexpensive
- Lightweight
- Usually have more drainage holes
- Easy to drill additional drainage holes
- heat andcool quickly tominimize root damage in hot weather.
- Generally, last only a few seasons
- Dry and crack with age and weather
Terra Cotta / Clay Pots
- Dry out quickly (porous)
- Take up water quickly
- Inexpensive
- Widely available
- Only one drainage hole
- Outside may stain from salts and minerals in water or soil
Concrete Pots
- Heavy- won’t blow over easily
- Available in larger sizes
- Good insulation which can protect plants/soil from temperature extremes
- Porous- may need to be sealed for water retention
- Lime may need to be rinsed out before planting
Wood Pots
- Usually lightweight
- Attractive
- Provide good soil insulation against too much heat
- Easy to DIY to exact specifications
- Require painting or sealing to prevent rotting
- Will eventually rot and splinter (especially the bottom- elevate to improve air circulation)
- redwood/cedar are rot-resistant
- Used pots can be added to compost
- May attract pests
Grow bags
- Excellent drainage
- Lightweight
- Easy to re-pot
- Easy to store after the growing season or move to a new location
- Generally considered temporary
- Not very attractive
When is the best time to re-pot?
The best time to re-pot your plants is when they’re dormant or growth slows. Every year or 2 transfer your plant into a pot 1-2 inches bigger than the current one to encourage healthy growth. Do not wait until the roots start to show through the drainage holes or the plant appears sick.
Where can I buy pots online?
You can purchase planters online at specialty garden suppliers such as
…or at hardware or department stores including
Summary
Choosing a pot that’s just right for your new plant is an easy task if you keep in mind the simple lessons we’ve learned.
- Take advantage of the perched water table to make watering easier.
- Research the water requirements of each plant to ensure your pot provides the proper drainage.
- Avoid pots that are too big and “pot up” every 1-2 years
- Choose a pot deep enough for the roots.
- Consider the location and drainage needs of your new plant when choosing the shape and material of a pot.
Enjoy your healthy plants in their appropriate planters!
We asked Amanda a few other questions you might find interesting: