Window box planters are a great way to add visual interest and greenery to the exterior of your home. Placing flowering plants in window boxes instantly livens up the look of a home’s facade. Window boxes also allow you to garden even if you don’t have a yard. With just a few simple materials and some basic tools, you can easily build your own custom window box planter.

Choosing a Location for Your Window Box Planter

When deciding where to install your window box, consider the following factors:

Sunlight

Most plants require at least 6 hours of direct sunlight per day. Evaluate the light exposure around your home and select a location that receives ample sunlight. South-facing and west-facing windows are ideal. North-facing windows may not get enough light.

Box Size

Measure the width of the window where you plan to install the box. The box should be slightly narrower than the window width. Standard window box sizes range from 24-36 inches long. Make sure to account for the added width of brackets.

Window Type

Window boxes can be installed below almost any type of window. Boxes below first floor windows may need to be securely installed into the house siding. For second story windows, choose lightweight planter materials.

Visibility

Maximize curb appeal by installing window boxes in highly visible facades at the front of your home. Place boxes below eye-level to make plants the focal point.

Convenience

Consider accessibility for installing and maintaining the box. Placing boxes beneath windows allows easy access for watering and pruning plants.

How to Build a Window Box Planter

Building a window box is a straightforward woodworking project. Follow these steps:

Choose Your Materials

Use weather-resistant lumber like cedar or redwood to construct the box. Avoid treated lumber which can leach chemicals. For a lightweight box, use PVC vinyl boards or composite wood.

Cut the Boards to Size

Cut two boards measuring the exact width of your window for the front and back of the box. Then cut two boards to the desired length for the sides. Standard lengths are between 24-36″.

Assemble the Basic Box

Attach the front, back, and side boards using exterior wood screws. Be sure to pre-drill holes to prevent splitting. Use angled screws to reinforce corners.

Install a Bottom Panel

Cut a board to size to line the interior bottom. This will prevent soil from leaking. Use small finishing nails to attach.

Add Waterproof Lining (Optional)

For extra leak protection, line the inside of the box with a waterproof polyurethane membrane before installing the bottom panel.

Attach Exterior Cleats

Screw cleats along the back top edge to hang the weight of the box on the window frame. Extend cleats the full width to distribute weight.

Install Brackets

Attach sturdy L-brackets along the back side edges to anchor the box to the house siding. Use corrosion resistant brackets.

Apply Protective Finish

Paint or stain the exterior surfaces of the box. A finish protects against weathering and prevents the wood from rotting.

Drill Drainage Holes

Drill a row of holes into the bottom panel to allow excess water to drain out. This prevents soil from getting overly soggy.

Add Interior Dividers (Optional)

For a multi-celled box, cut divider panels from thin plywood. Glue and nail dividers into place along the bottom panel.

Your basic window box frame is now complete! Continue reading for tips on choosing soil, plants, and accessories to complete your window box garden.

Selecting the Right Soil

The soil filling your window box will provide essential nutrients for plants to thrive. Here are some tips for choosing the ideal soil:

• Use a commercial potting mix instead of garden soil which can compress and inhibit drainage. Potting mixes contain peat moss or coconut coir to retain moisture.
• Look for a mix blended for containers that is lightweight, dense, and porous. The mix should evenly balance water retention and drainage.
• Avoid regular potting soil which can become dense and waterlogged in a box. Opt for mixes with added perlite or vermiculite to improve drainage.
• Use a quality organic potting mix with decomposed bark or compost for nutrients. Pre-fertilized soil can provide an initial nutrient boost.
• For prolific flowering, choose a mix designed for vegetables and flowers. This provides more nutrition from organic compost.
• Read soil bag labels closely to assess ingredients and nutrient levels to pick the best option.
• To save money, make your own potting mix using peat moss, perlite or bark chips, and organic compost.

Choosing the Right Plants

Selecting plants suited to window boxes will help ensure gardening success. Consider the following when picking plants:

Sunlight Needs

Choose plants that can thrive in the sunlight exposure your window location receives. Pick sun-lovers for south-facing windows. For less light, choose shade-tolerant plants.

Plant Size

Look for compact, low-growing annuals and perennials that won’t outgrow the confines of a window box. Trailing or cascading plants also work well.

Watering Needs

Drought-tolerant plants suited to window box growing include petunias, geraniums, sedums, verbenas, and lysimachia. Avoid thirsty plants like impatiens.

Bloom Time

Mix early, mid, and late-blooming annuals together to provide color spring through fall. Combine perennials and ornamental grasses with annuals for multi-season interest.

Theme

Create a cohesive look by choosing plants with a similar color scheme, texture, or growth habit. Or, opt for mixed planters with contrasting shapes and colors.

Fragrance

Scented plants like sweet alyssum, nicotiana, basil, and jasmine add sensory appeal to your window boxes when breezes waft their fragrance indoors.

Top Plant Picks for Window Boxes

Here are some of the best options for flowering plants that thrive in window boxes:

• Petunias – Offer prolific blooms all season long in many colors. Grow well even in partial shade. Spreading types cascade attractively.
• Geraniums – Provide bright color and last through summer. Look for heat-resistant varieties. Zonal geraniums work well in full sun.
• Fuchsias – Trailing or upright types available. The dangling flowers tolerate partial shade. Protect from excessive hot sun.
• Impatiens – Shade-loving with flowers in many hues. Keep soil moist. New Guineas offer more sun tolerance.
• Nasturtiums – Trailing types light up boxes with edible bright yellow and orange blooms. Tolerant of partial shade and neglect.
• Lobelia – Low-growing plants blanket boxes in vibrant blue. Combine with white alyssum for contrast. Require some shade.
• Verbena – Vigorous, heat-loving plants flower prolifically in sunny boxes with little fuss. Withstand drought once established.
• alyssum – Delicate white flowers emit a light fragrance. Thrives even in partial shade and spreads to fill boxes. Tolerates some drought.
• Ivy – Trailing English ivy cascades attractively from boxes. Grows well even in shade and adds year-round greenery.

Caring for Plants in Window Boxes

Window boxes require a little extra care since plants are confined to a small space. Follow these tips:

• Water daily, even twice a day in hot weather. Check soil moisture frequently. Water when top inch is dry.
• Fertilize every 2-3 weeks during the growing season with a water-soluble plant food to replenish nutrients.
• Prune back wayward, overgrown stems to keep plants tidy and in bounds. Pinch off spent blooms to encourage new flowers.
• Weed occasionally to prevent competition. Shallow boxes allow easy access for quick weeding.
• Inspect for pests like aphids. Wash away with water or use organic insecticidal soap. Treat diseases with fungicides.
• Deadhead faded blooms to maintain a neat appearance and promote new blooms.
• As plants decline, replenish window boxes with fresh plants for continued color. Fertilize when replanting.

Accessorizing Your Window Boxes

Beyond plants, certain accessories can enhance the look of your window boxes:

Box Numbers

Stencil or attach metal numbers displaying your house’s address. Choose numbering that complements your home’s style.

Decorative Brackets

Upgrade plain metal brackets with more ornamental scrollwork brackets to accentuate your window boxes.

Finials

Adorn the front corners of your window boxes with decorative finial ornaments for a classic touch. Opt for finials to match your home.

Lattice

Hide unattractive foundation walls below the box with sections of crisscrossed lattice attached between brackets. Paint to coordinate.

Planter Boxes

Nestle coordinating ceramic or metal planter pots into window boxes alongside plants for more interest.

Solar Lights

Line your window box with small-scale solar path lights to create a magical glow at night. Use lights with warm white bulbs.

Flag Mounts

Install flag mounts on window boxes to display seasonal flags and banners. Ensure flags are sized appropriately.

Trellises and Arbors

Anchor miniature trellises at the back of window boxes to support vining plants. Small arbors can also frame the window.

Simple Window Box Design Ideas

Want to give your window boxes a themed makeover? Here are some quick and easy design concepts to try:

Monochromatic

For a soothing, cohesive look, plant window boxes using varieties of a single color like all white, pink, or blue. Add interest with flowering and foliage textures.

Bold Brights

Pack a visual punch with vividly colored flowers like red or orange geraniums, purple petunias, and yellow marigolds. Intersperse with silver foliage plants.

Patriotic

Show your national pride with red geraniums, white alyssum, and blue lobelia. Or stick to red, white, and blue accessories in a mixed flower box.

Sunny Yellow

Conjure up cheering sunshine with masses of yellow blooms from flowers like marigolds, million bells, trailing nasturtiums, and golden creeping Jenny.

Herb Garden

Maximize window box function by growing an assortment of handy culinary herbs like basil, oregano, thyme, sage, parsley, and chives.

Pink Paradise

Velvety pink flowers evoke femininity and romance. Try different hues and forms using petunias, million bells, verbenas, begonias, and pink polka dot plants.

Silver and Purple

Combine silvery foliage from plants like dusty miller, curly parsley, and artemisia with vivid purple flowers such as petunias, pansies, cleome, and ageratum.

Ornamental Edibles

Mix edible ornamentals like nasturtiums, pansies, calendula, kale, parsley, and chives to create a unique window box kitchen garden.

Succulents

For low maintenance, fill boxes with interesting succulents, cacti, and sedums which require little watering once established. Mix shapes, textures, and colors.

How to Maintain a Thriving Window Box Garden

A flourishing window box garden requires some simple maintenance. Follow these key tips to help your window boxes look their best all season:

Water 1-2 Times Per Day

Plants in window boxes dry out faster than in-ground plantings. Check soil moisture daily, and water boxes when the top inch of soil becomes dry. Water thoroughly until excess drains from the bottom. Plants may require watering twice on hot, dry days.

Fertilize Regularly

Replenish nutrients leached from frequent waterings and fuel plant growth by fertilizing every 2-3 weeks during the active growing season. Use a water-soluble plant food and follow label directions to avoid burning tender roots with excess fertilizer.

Prune Overgrown Stems

Removing overgrown, leggy stems keeps plants compact and tidy. Prune back wayward shoots using clean pruners. Pinch off spent blooms to promote continuous flowering. Pruning encourages full, bushy, compact growth.

Weed Boxes

Pluck emerging weeds to prevent them from crowding out desired plants. Shallow window box soil allows easy access for quick weed removal. Check boxes weekly and pull weeds when small before they spread.

Check for Pests and Diseases

Inspect plants regularly for common pests like aphids, thrips, and spider mites. Wash away small infestations with a strong spray of water. For larger issues, use organic pest control like neem oil or insecticidal soap sprays. Remove afflicted leaves or stems to control diseases. Fungicides and copper sprays also help prevent disease spread.

Deadhead Faded Blooms

Remove spent flowers by pinching or snipping them off stems. Doing so encourages plants to produce more buds and blooms. It also keeps your window boxes looking neat and freshly flowering. Deadhead plants like petunias, geraniums, and impatiens routinely.

Refresh Plantings

As annual plants decline in late summer, replace them with fresh plants to rejuvenate the look of your boxes. Pulling out leggy annuals provides space for cool weather plants like pansies and kale. Replenish soil nutrients by mixing in compost or fertilizer when replanting.

With consistent care, your window boxes will thrive all season long, adding an eye-catching boost of blossoming color to your home’s exterior.

Window Box Design Inspiration

Looking for window box design ideas to add more curb appeal and personality to your home’s facade? Here are some creative ways to dress up exterior window boxes:

Go Grand with Multiple Boxes

Line an entire row of windows on your home’s front with matching window boxes for a grand statement. Having multiples provides continuity. Or experiment mixing different sized boxes on larger windows.

Cascading Flowers

For a show-stopping look, plant window boxes with flowers and vines that cascade dramatically down the exterior walls. Petunias, lobelia, and creeping Jenny overflow attractively.

Unusual Containers

Instead of traditional wooden boxes, get creative by installing metal buckets, woven baskets, or galvanized stock tanks as unique planters. Line with plastic to prevent leaking.

Mix Shapes and Sizes

Plant a collection of window boxes in varying lengths and designs. Combine rectangular boxes with half-rounded bay window boxes for an eclectic mix. Vary hanging heights for interest.

Contrasting Colors

Paint your exterior window boxes in a color that contrasts your home siding to make them really stand out. For example, use white boxes against a black or blue home.

Pick a Theme

Give window boxes a cohesive look by choosing a theme and selecting plants and accessories that complement it. Botanical, nautical, Tuscan, modern, rustic themes work well.

Light them Up

Use enclosed solar-powered LED strip lights to softly illuminate your window boxes at night. Conceal lights at the base or along the sides. Glowing boxes add magical ambiance.

Go Vertical

In addition to standard horizontal window boxes, also try incorporating vertical gardens going up and down on either side of windows for a modern, sleek statement.

Frame with Greenery

Flank outer edges of window boxes withtrailing ivy, ferns, or ornamental grasses. Spiller plants will frame and soften the boxes while also concealing hardware.

Unexpected Heights

Vary window box placement by installing some near the top of windows and others lower down to add architectural interest. Mix and match heights.

With some creativity, you can transform your exterior window boxes into stunning garden showpieces that enhance your home’s beauty and showcase your unique personal style.

Common Window Box Issues and Solutions

Window box gardening comes with a unique set of challenges. Here are some common window box problems and tips to resolve them:

Issue: Soil pulling away from sides

Solution: Before filling, line boxes with landscaping fabric to cover drainage holes. This keeps soil from escaping while still allowing drainage.

Issue: Plants wilting from inadequate watering

Solution: Check soil daily. Water whenever top inch is dry. Consider self-watering boxes or drip irrigation to maintain consistent moisture.

Issue: Water overflowing from drainage holes

Solution: Add more perlite, gravel or bark chips to soil to improve drainage. Drill extra drainage holes if needed. Let boxes dry out between waterings.

Issue: Plants dying from too much moisture

Solution: Avoid overwatering. Improve drainage by mixing peat moss into soil. Replace water-retaining soil with better-draining potting mix.

Issue: Plants stunted due to compacted soil

Solution: Aerate soil monthly with a small trowel or fork. Top dress annually with fresh potting mix to refresh nutrients and texture.

Issue: Faded blooms due to lack of sun exposure

Solution: For proper sunlight, only grow plants suited to the light levels your window orientation receives. Move sun-loving plants to a new location.

Issue: Leaning plants from strong wind gusts

Solution: Provide wind protection using screening or latticework. Stake tall plants to add support. Avoid large-leafed and fragile plants in windy areas.

Issue: Rotting wood from excessive moisture

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