We are finally outdoors! Our first round of plants are fully hardened off and survived their first evening in our greenhouse! Low temperatures hit 27 degrees Fahrenheit last night, but our heating systems worked wonderfully!
We will introduce our heating systems in more depth tomorrow, but this is always a monumental point in our garden’s transition every year. It’s kind of the point where our gardening season starts to become “real” and we can really start to see things come together.
It’s really important for us to communicate that our greenhouse can maintain minimum low temperatures through heating. If you can’t do this with your greenhouse, putting your plants out this early can be really, really risky. You might note that it feels like the tropics during the day in there. That’s not what’s important. What’s critical is overnight, where temperatures can equalize with ambient outdoor air. You can still get frost in the greenhouse!
Once we have our plants in the greenhouse, we really start to keep an eye on our overnight low temperatures. While we are generally expecting reasonable overnight lows in the 20’s up to our last frost, if temps dive way down into single digits, we will very likely bring our plants back inside. We aren’t really interested in exploring the absolute limits of our heating! If its insufficient against say, 5 degrees Fahrenheit, learning that limit could mean total loss of our plants!
This transition has also meant that we’ve been able to shut off two of our indoor grow lights for now. This is effectively the cost tradeoff that we’re looking at. While heating does have a direct cost, we’ll talk about why this makes sense for us.
For example, last night, our heating cost us about 3.98 kilowatt hours, or roughly $1.31. Our grow lights, in comparison, use about 2.8 kilowatt hours per day, or about 92 cents. At this very moment, yes, we’re spending more on heating than lighting. But, that scale very quickly tips as we get more plants into our greenhouse. What will generally happen is our heating costs will lower as temperatures rise, as will our indoor grow light costs since we’ll need less of them.
It’s been important for us to really look at the economics of this, given our high electrical costs and garden’s scale. The electrical load of all our grow lights running simultaneously is nearly 800 watts, or about $3.70 per day. Shaving kilowatt hours means real savings on our electrical bill, which is all ready hard enough to swallow this time of year!
We’re super thrilled that we’re marching closer and closer to gardening season. This weekend brings us to six weeks to last frost, so we’re getting ever so close!
