Posted by Brent Wilson on 8/13/2016 to Flower Gardening
Flower gardening in containers is perfect for the person who wants to have a flower garden but has limited time or space. Container flower gardens are great for adding interest and color to patios, porches, decks, steps, walkways, pool areas, and other outdoor spaces, and are convenient because they can be moved from one location to another.
Selecting A Container
The first thing you'll want to do is select a container that fits the setting it will be placed in, and one that will compliment the beauty of the plants it will contain without stealing the show.
Size matters. Match the size of the container to the size of the space you intend to set it. Unless your arranging several different size containers together in a grouping, you wouldn't want to put a tiny little pot on a huge back deck or patio. And you wouldn't want to put a gigantic pot on a small porch or balcony.
You'll also want to choose a container that will accommodate and match the mature size of the plant(s). Otherwise, if you put large-growing plants in a small container, the roots of your plant(s) will run out of room to grow, causing them to start declining long before the season is over. Too, a large growing plant in a small pot will require more frequent watering as the plant(s) grow, especially during the summer.
Color and style matters. Pick a color of pot that goes well with the colors of the plant(s) you intend to grow in it. Also consider the other plants and structural elements in the surrounding area. Pick a style of pot that matches the style of your home or space. If you live in a 1930's brick bungalow ultra modern pots with flashy bright colors might not be the best choice. Many nursery & garden centers offer a wide variety of containers to choose from, but just about anything you can find that holds soil and drains well is a potential container for a flower garden.
Drainage is all important. Make sure the pot you select has drain holes or are constructed of a material in which you can drill drain holes if necessary. Most clay and concrete pots provide excellent drainage and also allow air movement through the pot. That being said, clay pots are porous so the soil in them tends to dry out more rapidly than plastic and glazed ceramic pots.
Season of use. Keep in mind that non-glazed or waterproof-coated clay and concrete pots are porous and will absorb and hold water. This isn't a problem during the summer but during winter and freezing temperatures the water freezes and expands, which can potentially crack these types of pots. during the winter they will absorb water. So, during winter it's best to use pots made from materials that won't absorb water.
Most annual flowers growing in containers appreciate a moist but well-drained soil. Constantly soggy soil will often cause root rot or other harmful or deadly plant diseases. Therefore, we recommend using a high quality professional potting mix, not a cheap-grade potting soil. That being said, if you're growing fast growing annual plants that are known to drink more water and appreciate a heavier and more moist soil, you can thoroughly mix the potting mix and the potting soil at a 50/50 ratio for use in your container garden. Avoid using any native soil from your landscape as it doesn't drain good and aeration is very poor.
Basically speaking, when choosing plants to grow in your container flower garden, select ones that will grow grow best in the environment where the container will be placed.
If your container will be viewed from all sides, situate taller plants towards the center and lower growing or trailing plants around the edges. If your container will be placed against a wall, plant the taller varieties towards the back.
How much sun? Most of the plants you purchase to grow in your container garden will come with a plant tag that shows its light requirements. "Full Sun" means 6 to 8 hours or more of direct sunlight during the day. "Part Shade" means about 6 to 8 hours of shade or heavily filtered sun per day. "Shade" usually means all day shade or dappled shade, however most annual flowers that like shade, such as impatiens, will tolerate some sun in the early to mid-morning hours.
Pots situated on the east side of a home will usually receive shade in the afternoon, which means shade or part shade plants will work best. Pots situated on the west side of the home (with no trees or other structures to block the sun) will receive the hot afternoon sun, which means full sun plants will work best. Pots situated on the north or south side of a home will often receive full, all-day sun.
When combining a variety of plants in one container or grouping several pots in the same location, select plants that have similar growing requirements. Obviously, sun-loving and shade-loving plants are not very compatible unless the sun-lovers serve as an umbrella for the shade-lovers.
How much wind? If the site where your container garden sits is exposed to high wind, consider using lower growing plants.
Flower and foliage color. Annual plants come in an endless array of foliage and flower colors. When choosing flower colors you can go with a monochromatic theme using shades of the same color, or you can mix things up. When going with two or more colors consider choosing complimentary colors as shown in the color wheel below.
A color wheel is a diagramatic way of showing relationships between colors. Colors on the right side of the wheel are warm. Colors on the left side are cool. Colors adjacent to one another are analogous (similar). Opposite colors are complementary.
Color can be used to visually change distance perspective and to set a certain mood.
Warm colors express action. Light tints, such as red, orange, yellow and white, advance an object or area toward the observer. These colors and tints placed near the foundation of a house would make the house appear closer to the street.
Cool colors are restful. Deep shades like blue, green, purple and black recede and can be used to make the house appear farther from the street.
Habit of growth. Trailing or cascading plants are perfect for hanging baskets or to cascade over the edges of containers or pots. Upright and taller plants make good backgrounds or center pieces.
Plant spacing. When planting annual flowers in containers they will often be spaced closer together than when planting in garden beds. As a rule, twice as many plants can be used in a container as in a garden bed of equal space. So if your planting tag suggests a 12" spacing, space 6" in a container.
Step-By-Step Planting Instructions
Before filling your container with soil, we recommend lining the bottom with shade cloth or a porous landscape fabric. This will keep the drain holes from becoming stopped up with soil.
STEP 2 (Optional)
If you are working with a large, tall pot, and are planting it with smaller growing plants, you can place a pot upside-down in your container to conserve on soil.
Next, fill your container with the soil mix. Fill to the top of the container and then tamp so that the soil level is about an inch below the rim. If you want, mix in a slow- or timed-release flower fertilize with the soil at this time. Follow instructions on the product label for application rates.
Remove your plant(s) from their nursery containers.
Use one hand to pull back some soil in your container and the other to set a plant in the hole so that the top of the rootball is 1-inch below the rim of the container. Continue this process with any additional plants.
If you did not add fertilizer to the soil mix, fertilize with a slow-release release flower food or a water-soluble fertilizer. I prefer slow-release granular fertilizers.
Water thoroughly until water starts to drain from the holes in the bottom of the container. Add more potting mix and adjust plants if necessary if settling occurs during watering.
Step 7 (Optional)
Apply a 1/2" layer of wood chips or sphagnum moss to soil surface to help conserve moisture.
Care Tips Thereafter
Watering. Water requirements vary considerably based upon the type of plant(s), the soil mix that was used, the type of container, the amount of sun the garden will receive, and weather conditions.
Regardless of these factors, container gardens should be checked daily for water needs. Some plants, such as New Guniea Impatiens, drink a lot more water than others. These might require watering twice a day during the hottest parts of summer. Others, such as purslane or portulaca might require watering only once or twice a week, even in the hottest weather.
The best method for checking soil moisture is the finger test. When the top 2 inches of soil is dry it's time to provide some water. Water deeply until excess water flows from the drain holes in the bottom of the container. Then wait until the soil dries out a bit before watering again.
Fertilization. Annual plants growing in containers will have less soil to draw essential nutrients from and more frequent watering will leach fertilizers from the soil. This means they will require more food than those grown in garden beds.
When feeding plants growing in container gardens, I like slow-release granular fertilizers best because there's no mixing and they release a small amount of fertilizer every time the plant is watered. Some slow-release fertilizers last for an entire season while others might last a couple months or more. Other folks like using water soluble fertilizers which are applied much more frequently throughout the growing season. The choice is yours. Follow instructions and application rates on product label.
Deadheading. Some annual flowers are self-cleaning while others will benefit from deadheading (the removal of spent flowers.) Deadheading is a simple task which takes a few minutes. If you've never dead-headed before here's how go about it:
First, keep a watchful eye on your flowering plants, paying close attention to blooms that are past their best. Once a flower has started to fade remove it from the plant with a quick snip from your pruners, or nip the flower off with your thumb and forefinger if stems are soft enough. When deadheading, try to remove just the spent flower leaving the new buds beneath intact.
Pruning. During the growing season, remove damaged or dried leaves to keep the plants tidy and healthy. When trailing plants, such as petunias and verbenas, become long and leggy during summer you can rejuvenate the plant by cutting the stems back by half or more their length. Make sure there are some leaves or leaf buds on the remaining portion of the stem. Plants that have been cut back hard will not require as much water until newe growth has emerged.
In the Wilson Bros Gardens, we plant over 100 containers with annual flowers every season. We also grow a lot of small trees, such as Japanese maples, and mid-size shrubs in larger containers in the garden. We often use spreading annuals such as million bells (Calibrachoa) as a soil cover in these.
Below are some of my favorite annual plants.
Warm Season Annuals For Full Sun or Part Sun
Begonias (sun tolerant varieties)
Euphorbia 'Diamond Frost'
Licorice Plant (Helichrysum)
Juncus Grass / Rush
Million Bells (Calibrachoa)
Papyrus / Umbrella Palm
Sweet Potato Vines
Warm Season Annuals for Shade to Mostly Shade
Begonias (shade varieties)
Coleus (sun or shade varieties)
Fiber Optic Grass
Ivy (many varieties)
Juncus Grass / Rush
Oxalis / Shamrock
Spike Moss Selaginella
Sweet Potato Vine
Persian Shield (Strobilanthes)
Cool Season Annual Plants for Container Gardening
Juncus Grass / Rush
Cast Iron Plant
Dwarf Alberta Spruce - great as centerpiece and for holiday decorating
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