Petunia Window Boxes

Craving vibrant colors for your windows? Look no further than petunias! This post explores the beauty and ease of planting petunias in window boxes with the addition of trailing sweet potato vine. Learn key tips for about planting techniques, and ongoing care to ensure a cascade of blooms that will transform your home's exterior all season long.

How to plant your window flower boxes

Not sure how to take care of your petunias when they start getting long and leggy? Here is the info you need in the post called Pinching Back your Petunias.

Preparing the window box

Make sure there are drainage holes at the bottom of the planter.   Plants don't do well if their roots stay soggy.  If the roots are wet all the time and don't dry between watering, they can suffer from root rot. If you have a window box attached to the house, use a liner to protect the wooden boxes from damage.  In this example today, there are plastic window box pots that get inserted and then there is also a plastic liner to protect the wood from damage from all the water.

The bottom of the plastic planter container is lined with plastic so that the water doesn't run out and damage the wooden planter boxes.  The planters need to be watered about once a day (twice during those hot days).  Don't plant petunia flower boxes if you can't commit to the regular watering!!

Removing old soil and adding new

Each spring, about ⅓ of the soil from the previous year is taken out and replaced.  There were some seriously strong recommendations for Miracle Grow potting soil with moisture control (I love the stuff too!!). When you have window boxes, make sure you use potting oil (not top soil, or ground soil etc.). It does make a difference.

Fertilizing

And the magic to make these beautiful window boxes grow so beautifully?  These petunia and sweet potato vine window box plants get watered in with a weak mixture of Miracle Grow after they are planted.  After that, they get fertilized roughly every second week (diluted to ½ of the manufacturer's recommendation).  There isn't a lot of soil in the containers and the plants need all the help they can get!

Do I plant traditional thriller, filler, and spiller plants?

The thriller, filler and spiller plant formula is a traditional combination of plants that looks great in a planter. If these terms are a mystery to you, I've described them in detail in my post called
31 Outdoor Planters for Ideas and Inspiration
If the window box is under a window, I often don't put in a tall thriller type plant. In some cases the window box looks better when the plants and flowers are the same height across the planter and flowers or interesting leafy plants trail down.  In this example the petunias and potato vine will grow to roughly the same height and will trail down the window frame.

Watering

Plan to water daily! When it's hot and sunny, you may have to water twice daily. Often the plants start to droop. Stick your finger a couple of inches into the soil and if it's dry, you need to water.

It often takes a couple of weeks for the plants to establish themselves.

Then they thrive! You will definitely know when they are happy!!

Yes, I think I love the idea of a built-in window box under my front windows.  Hmmmm, I'll have a long winter to give it some thought!

As promised, here is the window box planter a little later in the summer!  Didn't it fill in nicely?  I love the bright pink petunia and the spikey green sweet potato vine.  Such a bright and fun contrast in colors!

Later in the summer, here is a whole-house view of the house with a beautiful window planter box under most windows. I love this look and think it has a European flair. Petunias have such long seasonal blooms that they last the whole summer and even into the fall. Unfortunately, a hard frost marks the end of the season for these guys!

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**Originally published June 2015.