Horticulture Principles and Practices

media hold water and make it available to the plants. Because of its physical structure,
rockwool will also improve water holding capacity when added to a soil-less media.
Saucers placed under the containers are also good for reducing watering frequency. On
the other hand, amendments such as coarse bark or perlite can be added to improve
drainage.
Homeowners will need to fertilize their container gardens. One teaspoon of a water
soluble 20–20–20 dissolved in one gallon of water applied every two weeks will supply
about 300 ppm N which is enough to keep the plants healthy. Or, an encapsulated, slow
release fertilizer can be sprinkled on the potting media surface. Slow release fertilizers
are sold at garden centers and one can follow the directions on the package. The fertility
is released from this type of fertilizer when the potting media is watered. When watering
with plain water or when applying soluble fertilizer, hold the watering can spout or
hose nozzle at the rim of the container and add water until some water leaks from the
drainage hole in the bottom. This should take a few minutes, so make certain that the
water is being soaked up by the entire root area and not just dripping down the inside
wall of the container and out. One way to check for this is to lift or tilt the container
enough to feel if it is getting heavier as it is being watered.
It is best to grow or purchase plant material for a container garden that is already
starting to flower or otherwise maturing in 4 to 6–inch size pots and then plant them
together in the final large container. Keep the plants in their pots and arrange them on top
FIGURE 6 The focal point lies deep in the center of this container
garden and is established by the radiating leaves and
emerging flower of eucomis ‘Bicolor’. Its unusual plant form and
hefty leaves also help to grab attention. A microclimate is formed
underneath the canopy of eucomis and coleus ‘Sedona’ to filter
light for the shade-loving plants below which include tatting fern,
huechera ‘Amber Waves’, ajuga ‘Black Scallop’, hosta ‘Fragrant
Bouquet’, impatiens ‘Infinity Salmon’ and streptocarpella
‘Conord Blue’ (clockwise). The terra cotta color of the 14 tall X
11.5 wide decorative container contributes to the blue and
orange complementary color harmony. Designed by Terri Starman
Photographed by Kristen Eixmann
FIGURE 7 Curcuma petiolata ‘Emperor’ (Siam Tulip) forms
the center, while Breynia, Japanese forest grass ‘Aurora’, and Japanese
painted fern serve as fillers. Caladium ‘Florida Sweetheart’
is the focal plant in the corner position and Lysimachia nummularia
is in two edge positions. The various plant species are compatible
for a shady location on the patio. Designed by Phil Campbell
Photographed by Terri Starman
356 Chapter 11 Growing Houseplants