How to Start and Maintain Your Own Window Box

Window boxes are a joy. They are easy to start and maintain. They provide the gardener with immediate satisfaction and bring a smile to neighbors and passersby. They provide gardeners with year-round pleasure. You can add or replace plants as the seasons change and create holiday themed boxes. 

Keep in mind that window boxes are not just limited to flowers; you can also grow vegetables, herbs and strawberries. You can also combine flowers with edibles.   To be on the safe side, combine herbs and vegetables with edible flowers.

Here is a short list of edible flower: Marigolds (Calendula), Carnations (Dianthus), Begonia (Begonia X tuberose or Begonia cucullata), snapdragons, garden salvia, petunias and nasturtium. 

Choosing Plants for the Window Box

The most important factor when choosing plants for a window box is the location of the box and amount of sunlight it will get. Plants have different sunlight requirements and need to be sited appropriately.

Plants are labeled “full sun," “partial sun," "partial shade” and “shade."   Full sun plants require at least 6 hours of direct sunlight per day including midday sun.  Partial sun or shade plants will not tolerate the midday sun and are best for a location that gets morning or afternoon sun.  Shade plants cannot tolerate direct sunlight.   

Follow these general guidelines: If your building faces south, choose full sun plants; if north choose, choose shade; and if east or west, choose partial sun or partial shade plants.    

Home and Garden Magazine offers over 35 plans for sun or shade window boxes. When shopping for plants read the labels; this will provide information on the plant’s light requirement and potential height and width. 

Choosing a Window Box

Commercially available window boxes come in a variety of shapes, sizes and materials; plastic, wood, vinyl, fiberglass coconut coir and metal.  Homemade boxes, (for the environmentally conscious) include recycling old coffee cans, water or soda bottles or old milk and juice cartons which can be painted and grouped together to make an attractive display. 

Smaller boxes as well as boxes made from wood, clay and coconut coir dry out more quickly than plastic boxes and will need more frequent watering.  Use self watering window boxes is you have a busy schedule and cannot commit to daily watering. 

While these boxes tend to cost up to 3 times as much as a basic box, you will appreciate them during the dog days of July and August when daily watering is a must.

Planting the Window Box

Most importantly, make sure your window box is securely mounted to the window sill and there is no risk of the box falling.  As a general guideline, place taller plants in the center and at the back of the box, shorter plants and trailer in the front and on the sides. 

1)    If soil is dry, water your plants and set them aside to drain.  Cover the drainage holes in the box with gravel or small rocks (you can find these at your garden center), then add a thin layer of newspaper

2)    Fill the window box half full with potting soil and water until soil is evenly moist. Remove the plants from their containers.  If the roots are matted or coiled gently tease them apart with your fingers.   Arrange in the box leaving two to four inches between plants.  Take a look at your design from inside your house and from the street.  Make any adjustments.  You may need to raise or lower the soil level depending on the size of the root ball. Remember to moisten any added soil.  The root ball of the plant should be at the same level it was in the container. When finished the soil level in the box should be one inch below the top of the box. 

3)    Once you have settled on a pleasing design fill in the soil between plants gently pressing the soil in place. Gently water plants until water leaks from the drainage holes.  A watering can with a shower head is best for the job.  Add more soil if necessary and water again.

Maintaining the Window Box

1)    Check the box regularly (daily in July and August) by inserting a finger about a half inch into the soil.  If the soil is dry, water it until water leaks from the drainage holes.

2)    Regularly remove dead flowers; this will speed up the process of the plant producing new flowers.  Some plants like petunias may need to be cut back periodically. If the shots look thin and straggly, cut back by half to encourage growth and more blooms.

3)    Fertilize your plants with liquid fertilizer following the instructions on the label.

4)    Enjoy!!!

As the summer fades, so will the plants.  In the fall replace summer annuals with mums, flowering cabbage or kale. Also tuck in a few bulbs (crocuses, narcissus or hyacinths) for early spring flowers.

For the Christmas season, plant a mini tree or other small evergreen; these plants can be re-potted in the spring and kept indoors in a sunny window until the following year. 

If you would like to learn more about designing, planting and maintaining window boxes the Brooklyn Botanical Gardens is hosting a class on May 14. I encourage all block associations to enter the Greenest Block in Brooklyn Contest -- lots of window boxes can be a big part of gaining points with the judges.

Over the past few years, Bedford-Stuyvesant blocks have continuously had a proud showing in this competition.  In 2008, nine of the 38 winners and/or honorable mentions were in Bedford-Stuyvesant.

Next article: "Growing and Creating Beautiful Container Gardens"