Happy Easter, everyone! We’re nine weeks to our last frost, just one more week away from when we really start getting busy with the growing season! If you’re planning to grow from seed this season, the point of no return will soon be upon us!
We should have covered this topic earlier in the season, but we’re just now getting around to it here! Better late than never! And that is if you’re working with modern, high power LED’s, let’s talk about how we “dial them in.”
The gist is that today’s high power LED’s are extremely powerful, like they can fry plants powerful. This is actually good for us since it allow us to use them quite differently than the less powerful lights of year’s past. The general goal with them is to raise them up a fair bit above the plants and allow them to cover a larger physical footprint.
The way we figure out the right height with them is by using a lux meter app on our phone. This allows us to generally measure the strength of the lighting. We generally aim for about 20,000 lux at the seedling’s height, right under the under the light. For our lights, that’s right about 24 inches above the seedlings. This will generally ensure our smallest plants will get at least that, and usually a bit less as they spread out from beneath the center of the light. With the lights we use, we can usually get about a 3×3 space covered with fully adequate light strength.
In case you’re curious about how this compares to something like compact fluorescent bulbs, even a large CFL fixture (e.g. 6 bulbs) might produce half that amount of light literally right under the bulbs. This is one of the biggest reasons for our upgrade to high power LED. We can cover more physical space with less overall power usage AND get better light quality overall. The end result is quality, compact garden starts that rivals commercial quality in every way. The power savings shifting to LED was enough to pay for the upgrade within three short years for us!
We rarely change the height of our lights through the indoor growing season. As the plants grow, we let them grow into the more powerful light. They are bigger at that point and can thus handle it. A nice sunny day will measure like 60,000-80,000 lux (or even more) on your phone, so we have quite a bit of light strength to work with. The only time we might consider raising our lights is if the plants get super tall (e.g. tomatoes) and we might raise one light a little bit just so they aren’t growing right into our lights.
We’ve got our first temporary grow table set up for the season! In most years, we have to set up two of these as we need them. This is how we handle the inevitable expansion of our bustling indoor garden and handle the constant unfolding of our up-potted plants!
