Find out how to create beautiful window boxes that will complement your home's exterior. Get tips on choosing the container material, soil type and flower varieties. Learn how to attach the window boxes to the outside wall.
LESLIE: Window boxes are a great way to quickly dress up the front of your home and complement your home’s architectural style.
ROGER: Welcome to my window world.
TOM: You know, it seems that window boxes might be one of the fastest ways to add a bit of landscape  to your house without really having to dig out the shovels, right?
ROGER: It’s truly amazing to be able to fasten something to the house and the same day fill it with plants and have it look so nice.
TOM: It’s like sort of an instant result.
TOM: Now, when you’re trying to decide what kind of window box works best for you, what do you consider? Style of the house important?
ROGER: Always important to try to match the style of the house but also in my mind is durability. I want something that’s going to last a long time and not disappear on me in a year or two.
TOM: And do you think it looks best when you have a window box mounted as the same width of the window as opposed to just halfway or something?
ROGER: Yeah, I think it’s essential to line up with the edge of the windows. It just gives it a finished look like it was part of finished carpentry of the window.
LESLIE: Mm-hmm. So if you’ve got three windows that sort of sister each other side by side, you want one long box; you don’t want three individual guys.
ROGER: That’s what I do at my house; I run it the length of them.
LESLIE: Mm-hmm. Now, it’s got to be very important to think about how you mount these boxes because their weight is going to range, depending on how watered it is, what the weather is doing. So how do you know you’re getting a secure mount?
ROGER: If you have wood siding on your house, it’s pretty easy to anchor into the wood and be sure. If you want to, you can always find the studs. There are several ways to find studs. You can rent Tommy Silva and his knuckle and he’ll find it for you. But if you can find the studs or the structure, anchor it into that.
And it’s more essential that you do that in PVC because if you put a window box on it and it’s just held on by the PVC siding, there can be a lot of problems with that. Tommy did a great example of that on one of the shows we did. And he showed how to find it, drill it and mount a box in that fashion so that they’ll stay put.
TOM: Yeah, now, I saw that and I guess the technique was to drill through the siding with a slightly wider bit than you would need to hold the screw and then put lots of caulk around it, basically. So you don’t want to create any holes where the water will get behind the box and into the structure of the house.
ROGER: No. But you want a little oversize hole because vinyl is always moving. It moves more than wood and it has to have an area to move or it’ll crack.
TOM: Yeah, good point.
Now, you mentioned PVC is one of the materials for these boxes. Is that one of your favorites?
ROGER: It is because it stands the test of time. And it just will last forever. I’ve done plastic, I’ve done wood. The plastic tends to bulge if you fill it too much and the wood, over time unless you paint the inside, will rot.
LESLIE: Will rot.
TOM: And so many people think of PVC – are associated with plumbing pipes. But what we’re really talking about here is cellular PVC , which looks just like wood.
ROGER: You can’t tell the difference.
TOM: Absolutely not.
LESLIE: No. And it really stands up.
Now, when it comes to the soil that you’re going to fill in these window boxes, do you need a special type to be more absorptive or help the plants grow more? Because it’s such a confined space.
ROGER: Window boxes are the smallest space you’ll ever plant in, even smaller than big planters you use on the front of your house on the walkway, so you want to do everything you can. Use a good soil that has a lot of peat and vermiculite in it and also a soil that has a water-absorbent quality, those little polymers they put in that absorb the water when you water and then slowly release it as the soil dries out, so it buys you more time between waterings.
TOM: Now let’s talk a bit about the type of plants that work best in a window box, because it is hanging off your house and you’re featuring it. Are hanging vines and that sort of thing a good choice for that? Any favorites?
ROGER: You can have a ball with window boxes. I love putting a lot of hangers. One of my favorite is sweet potato vine.
LESLIE: I love them.
ROGER: It comes in a chartreuse and even a dark purple and that can be such a great color. And they’ll grow 3 to 6 feet and just hang all the way down to the ground.
Then I do fillers. I use a lot of colorful things. Even geraniums are great fillers. And then I usually put one big plant in the middle. It can be as simple as a grass or a dracaena, something to give me some real height, some drama in the middle of the box.
LESLIE: How much depth are you needing to create these little mini-gardens?
ROGER: You’re starting with small plants in small pots. So 4 to 6 inches is plenty.
TOM: And finally, let’s talk about watering. Very, very important. Any systems out there to make the watering process a bit easier?
ROGER: There are a lot of systems out there but the one we highlighted on one of our shows was a PVC planter box with a plastic system inside with cotton wicks that you filled and then the water wicked up into the soil. It was a great system.
TOM: Very cool. So you fill this pipe up with water and it wicks right out and keeps the soil moist and damp.
ROGER: Right. So you may have to water only once a week and that’s better than going there every day and trying to get water …
LESLIE: And it’s actually putting the water where you need it.
ROGER: Again, down in the roots.
TOM: Roger Cook, the landscape contractor on TV’s This Old House, great advice. Thanks for hanging out with us as we talk about hanging window boxes on your house.
ROGER: Well, I hope you enjoy your window box.
TOM: We will. Thanks, Roger.
LESLIE: Alright. Catch the current season of This Old House and Ask This Old House on PBS. For local listings and step-by-step videos on many common home improvement projects, visit ThisOldHouse.com.
TOM: And This Old House and Ask This Old House are brought to you by The Home Depot. More saving, more doing. That’s the power of The Home Depot.