The key is to use a webcam and a time-lapse video program. I used Timelapse and I highly suggest it. It’s free and easy to use, and you can control a lot of variables. Timelapse is no longer supported by its programmer, but he gave me permission to share the link to the download, which is hosted in my Dropbox. I also bought a USB webcam for our laptop from Amazon. My original camera was not high quality,but it did the work. I ended up getting a Logitech C920 Webcam for other work, and that’s what I used to shoot the video in this post.
I put the webcam in a second-story window and set up the time lapse. I set it to start early in the morning and let it run all day. This works best when you are out of the house and don’t need to use a computer all day!
This is a phenomenal way to see exactly how many hours of sunlight a spot in your yard will receive. Take a look at the video I shot here and then I’ll explain how to interpret it.
A time-lapse is made by taking a photo at a specific interval (I do a half minute) and then stitching together those hundreds of photos taken throughout a day. Here’s how I calculate the exact time that a spot of dirt gets.
The TimeLapse program stitches the photos together at 15 photos per second of video. We know that the camera takes a photo every thirty seconds.Therefore, one second of video time represents 7.5 minutes of actual time. And here’s another easy thing – eight seconds is an hour of real time (60/7.5=8).
I make note of the time in the video when the sunlight first hits a spot. Let’s say that’s at 0:18 of the video. The light stays on it until 0:41. Twenty-three seconds have passed. Since every eight seconds make up an hour, this means that I’m just shy of three hours of sunlight. Practically, that means that I’m on the lower end of what “half sun” means on a packet of seeds.
With my cold frame (that box you see on the left side of the video), It has sunlight from the beginning of the video (9:15am) to 0:41 in, when the house starts to shade it. That means it has a little over five hours of sunlight on it. Not great, but I’ll take that kind of sunlight in the winter. I fretted about where to put it, but it’s hard to find another spot that gets more than five hours at this time. You can test that, too – start the video, put your mouse pointer on the spot and see how long it is in full sun.
The light patterns in your yard will change during the year. I try to take a video every two months or so. Leaves on trees make a significant difference, as does the height of the sun. When you do this, you will probably find winter gardening spots that are bathed in light once the leaves have fallen. Perfect for a cold frame!
This is the only foolproof way to see how many actual hours of sun a space in your yard will get. Take the guesswork out of where to plant expensive flowers and trees by making a simple time-lapse. Plus, they’re mesmerizing to watch.