Practical Organic Gardening: The No-Nonsense Guide to Growing Naturally (Cool Springs Press, 2017), by Mark Highland is a modern visual guide to growing organically. The book provides step-by-step photography and how-to projects so readers can take a hands-on look at updated popular gardening techniques. The following excerpt is from Chapter 10, "Organic Container Gardens."
Just as following the proper planting technique is important to ensure the health of in-ground plants, so it goes with container garden plants.
Consider Container Weight
When considering container options, don't forget the weight factor. Ceramic containers are much heavier than plastic, and once they are filled with soil they are even heavier. If potting large ceramic containers, place them empty in their final location before adding potting soil. One way to make containers lighter is to reduce the amount of soil added. For containers larger than 24 inches tall, you can place something in the bottom of the container to reduce the amount of soil needed. There are products specifically designed for this purpose, such as pot inserts that come in a variety of sizes. Even a 2- to 3-inch reduction in the amount of soil in the bottom of the pot will help reduce weight.
There are also planter movers that, like appliance movers, have straps that "hug" the pot and allow you to safely move it. The straps go over your shoulders and allow you to lift the pot with your legs and not your back. Always test the lift before putting the full weight of a pot on yourself, and ask a friend for help. If in doubt, leave the pot where it is until the season is over, then remove the soil before moving the pot to a new location.
You can also buy a base with locking wheels and place the container on it before filling with soil. Wheels allow you to move the container around easily. Don't forget to lock the wheels back in place when you're done moving so it doesn't run away. Wheeled bases also keep the pot off the deck or patio, which helps reduce the incidence of "pot stains" that inevitably occur when any container sits long enough on a deck or patio surface. These pot stains can be scrubbed or pressure-washed off a deck easily, but the staining can also be reduced by using "pot feet." There are many different manufacturers of pot feet, but they all function the same way, by elevating the pot slightly off the deck surface to minimize any staining. All potting soils have a tendency to stain slightly, as they are made from organic matter that is constantly breaking down.
Select the Right Potting Soil
Container gardens require potting soil, which is not the same as garden soil. Remember, garden soil consists of sand, silt, and clay. Potting soil, on the other hand, is actually a soilless mix with specific properties formulated to perform well in container gardens.
Containers do not thrive if you dig up soil from the backyard to use as your container soil. Not only will this soil have less air space, but it could also transfer pests or diseases into your container gardens. Look for potting soils made for outdoor use when shopping for your outdoor container gardens. Outdoor, all-purpose potting soils are designed to provide good drainage to avoid over-saturated containers. Indoor houseplant potting soils are designed to hold water a bit longer than outdoor soils, because indoor houseplants generally go much longer between watering. Comparatively, outdoor containers dry out faster and need to be watered several times per week during the growing season.
One of the drawbacks of a container garden is that they are less forgiving than gardens in the ground. This means that if you forget to water for a few days, your container gardens could dry up and be quite crispy by the time you get around to watering them. Fortunately, in most cases their beauty and joy outweigh the work of frequent watering.
To combat the frequent need for water, container gardens can be planted with potting soils that are formulated to hold moisture. Look for potting soils that contain ingredients with superior moisture-holding abilities, including compost, worm castings, and coconut husk fiber. Check potting soil labels closely, as some products have chemical polymer crystals added to absorb water, which are not organic.
What about adding gravel and pot shards? Some people swear by adding gravel or stone to the bottom of big, ornamental pots to increase drainage. Not only does this make the pots even heavier, but it also does not improve drainage. The soil above the gravel layer holds moisture longer than if there were no layer of gravel. By adding two distinct layers of materials — the layer of gravel and layer of soil — you create what is known as a perched water table and the upper soil layer must completely saturate before any drainage can occur from the soil layer down through the gravel layer. Plastic pots generally have enough drain holes in the bottom of the container to allow for good drainage.
Garden long enough and you'll accumulate many broken terracotta pots. These can be broken into shards that can be placed in the bottom of a container. Place one shard directly over the drain hole if planting in a new terracotta container (there is usually only one drain hole in terracotta containers). Ideally, the shard should curve over the drain hole to keep soil from blocking it and clogging up the drain hole. Place a couple others around it to make sure soil doesn't block things up. Larger pot shards work best.
How to Plant a Container Garden
- Select your container. Make sure it's clean and free of any debris.
- Assemble your plants for the container. Make sure the plants are watered well and not dry. Note which plant is in the largest-sized pot and how large that pot is, as this impacts the next step.
- Add enough soil to fill the container to the level where you can drop in your largest rootball so that the top of the rootball will be about 1/4- to 1/2-inch below the top of the pot.
- Remove that largest plant from the pot, and place it in the container. Add soil around the base of the plant's rootball just so the plant does not fall over.
- Repeat the process of adding soil until you have enough placed to support the filler plants and keep all the rootballs at the same height (about 1/4- to 1/2-inch below the top of the pot).
- Place the filler plants. Once they're added, fill in any gaps with soil so there are no empty pockets of air in-between plants.
- Add your spillers at the pot edges, making sure to line up the rootballs so they are at the same height as the rest of the plants.
- Fill in any remaining gaps with soil so the soil line is the same height across the entire container. Pay special attention to the edges to make sure soil surrounds the rootball of every plant.
- Pick up the planter about 1/2-inch off the ground, then drop it (gently) to the ground after all plants are in place. This helps settle the soil into place and improve soil to rootball contact.
- Move the container to the spot where it will live. Then water it well. If you water in before moving it, you just make the container heavier.
More from Practical Organic Gardening:
- Caring for a Container Garden
- Designing Your Container Garden
- Grow Houseplants Organically
- Organic Container Gardens
- The Right Container for Your Garden
- Cultural Considerations for a New Garden
Excerpted with permission from Practical Organic Gardening, by Mark Highland. Published by Cool Springs Press, © 2017.