How to Grow Beautiful Flowers in Window Boxes

Fill window boxes with quality potting mix, choose flowers suited to your light conditions, and water regularly while ensuring proper drainage for vibrant blooms all season long.

1. Pick the Perfect Container. Select a box that's at least 8 inches deep and has drainage holes. Plastic boxes retain moisture better, while wooden boxes provide better insulation. Metal boxes heat up quickly and may cook plant roots in direct sun. Make sure your box is proportional to your window - it should be roughly two-thirds the width of your window for the best look.
2. Prevent Root Rot Now. Place a layer of gravel, broken pottery, or drainage stones in the bottom of your box. This prevents water from sitting around the roots and causing rot. If your box doesn't have drainage holes, drill several half-inch holes every 6 inches along the bottom. Without proper drainage, even drought-tolerant plants will fail.
3. Lay the Foundation Right. Use a high-quality potting mix designed for containers, never garden soil. Garden soil becomes too heavy and doesn't drain well in containers. Fill the box to within 2 inches of the rim, leaving space for watering. Mix in some slow-release fertilizer granules according to package directions to feed your flowers throughout the growing season.
4. Match Plants to Light. Choose flowers based on your window's light conditions. For full sun (6+ hours), try petunias, marigolds, or geraniums. For partial sun (3-6 hours), consider impatiens, begonias, or coleus. For shade, go with caladiums or torenia. Pick a mix of upright plants for the center and trailing varieties like ivy geraniums or bacopa for the edges.
5. Create Instant Fullness. Space plants closer together than you would in garden beds since window boxes are meant to look full immediately. Place plants about 4-6 inches apart, alternating heights and colors for visual interest. Plant trailing varieties along the front edge so they can spill over attractively.
6. Master Daily Watering. Window boxes dry out faster than garden beds, especially in windy or sunny locations. Check soil moisture daily by sticking your finger into the soil. Water when the top inch feels dry, usually every day or two in summer. Water slowly and thoroughly until you see water draining from the bottom holes.
7. Keep Blooms Coming All Summer. Deadhead spent flowers weekly to encourage continuous blooming. Pinch or cut off faded blooms just above the next set of leaves or buds. Feed with liquid fertilizer every two weeks since frequent watering washes nutrients from the soil. Replace any plants that decline or finish their bloom cycle with fresh ones to keep boxes looking vibrant.