How to Install a Window Box (aka window flower box)

Window boxes. They're beautiful, but they can also be a pain to have installed properly. Often times it's better to have a professional carpenter or installer do it for you. But for the do-it-yourselfer, below is a blueprint for helping you to figure out the best way to install a window box planter.

There are multiple considerations to take in when planning your installation: (1) How much weight can it support? (2) Is it mounting to brick, rock, or siding? (3) What type of material is your box made from? (4) How large is the box? (5) Will additional support brackets be used?

Because most window box planters are designed to hold a significant amount of weight, it is usually a good idea to mount the window box to the house with the most secure fasteners availble. Sometimes, these will be provided by the manufacturer. However, oftentimes, this may not be the case, especially if you have decided to build your own window box.

One of the most secure forms of fasteners is a 3/8" lag bolt with a 2" washer that goes directly through the back end of the box. This is usually the preferred method for wooden window boxes and rot free PVC window boxes, but not fiberglass. Most planters usually measure about 10" tall and 10" deep and a good rule of thumb is about one lag bolt for every 18" of box length. However, larger planters will need a multitude of lag bolts anchored securely into the houses exterior to ensure that they are secured safely.

These are the steps you will need to follow when hanging your window box.

1. Measure and mark the center of your box and measure and mark the center of the window where you will be hanging it
2. Drill 3/4" holes in the back of your box spaced approximately 18 inches apart.
3. Have someone help you hold the box up centered underneath the window and mark with a pencil on the house through the 3/4" holes. Take the box down and set it aside.
4. Now, you are ready to predrill some holes into your house to receive the lag bolts that will be holding up your window box. If your house is brick, you will want to use an expandable lead anchor shield that can receive a 3/8" lag bolt. Usually, a 5/8" lead anchor will do the trick. This means you will need to predrill a 5/8" hole exactly where you have marked with your pencil. For brick and rock, you will need to use a hammer drill. Most 24-V screw guns can perform a hammer action, otherwise you may need to rent a hammer drill from your local area. Drill over marked areas making sure to drill deep enough to receive the lag bolt. Siding and/or stucco will not require a hammer action drill and a standard 14-V drill should be able to do the trick.
5. Tap the lead anchor into the wall with a hammer.
6. Have someone help you hold the box up centered and now you are ready to insert the lag bolt and washer through each hole of the box and into the receiving lag bolts that are hammered into the wall.
7. Tighten each lag bolt about 90% and remember to use a level then tighten the remainder until washers grab tightly against the back of the box.
8. Viola, you're done.