Step 1: Prepare the soil. Pour potting mix into a bucket and add water until the soil feels like a damp sponge. Stir in a time-release organic fertilizer, such as Dynamite. For full-sun and shade boxes, add a moisture-retaining polymer, like Soil Moist. Cover drainage holes with coffee filters, then fill two-thirds of the box with the potting mix.
Step 2: Plant the box. Arrange plants, still in their pots, on top of the soil to approximate their positions. Gently tip them out of their containers. Start planting in the center of the box and work toward the sides, adding more soil around the roots as you go. The final soil level should be about an inch below the top of the box.
Step 3: Water lightly. Moisten the base of the plants to settle them into the soil and eliminate air pockets. Add more soil as needed. Place or hang the box beneath the window and water thoroughly until the drainage holes start to drip.
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If You Have a Sunny Window
What to Plant
Bright, showy flowers are at their best in a box that gets at least six hours of direct sunlight between 10 a.m. and 6 p.m. So go for reliable bloomers in arresting color combinations. In this box: Dusty Miller (Senecio cineraria Cirrus), Calibrachoa (Calibrachoa Superbells Red), Verbena (Verbena Sissinghurst), and Sweet-Potato Vine (Ipomoea batatas Margarita).
To add contrast, set the flowers against a backdrop of foliage in a variety of colors and textures.
When to Water
Daily, depending on rainfall and the season. To be safe, water when the soil feels dry an inch down.
How to Maintain
Add a balanced water-soluble fertilizer every two to three weeks for extra growth potential.
If you see spent blooms, pinch them off so the plants can flower more prolifically.
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If You Have a Shady Window
What to PlantLook for shade-happy plants with colorful leaves, like the four vivid varieties of coleus that fill this box (Solenostemon scutellarioides Kiwi Fern, Dark Star, Dappled Apple, and Dark Heart). Play with contrasts in texture and hue. Here, the ruffly maroon-and-coral Kiwi Fern anchors the middle of the box, offsetting the deep purple and apple green foliage surrounding it.
When to WaterDaily during the hottest summer days; the rest of the year, check every few days and water as soon as the soil is dry to an inch below the surface.
How to Maintain
Pinch off new flower spikes and stem tips every two weeks to keep plants looking lush and full.
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If You Have Limited Time to Garden
What to PlantSucculents thrive on neglect. They love to bask in the sun, and they won't dry out, because their fleshy leaves have a built-in water supply. Choose a visually varied composition of succulents with similar light and moisture requirements. In this box, small purple echevaria rosettes (Echeveria Perle von Nurnberg) echo the shape of their giant green aeonium cousins (Aeonium subplanum). Blue chalksticks (Senecio serpens) and green rattails (Crassula muscosa) create contrast, as does a trailing cape ivy (Senecio macroglossus Variegatus) and a black rose aeonium (Aeonium arboreum Zwartkop).
When to WaterInfrequently. Check the soil every two weeks, and reach for the watering can when the soil is completely dry.
How to MaintainMake sure to use a fast-draining, soilless potting mix designed for succulents and cacti.