On April 26th, we were finally able to move our plants out of the house and down to our high tunnel. Each year this is always an exciting time for us. It’s rewarding to see all the plants ready to move on to the next step. We started many of our plants on March 16th, so the earliest ones spent about 6 weeks in our plant stands. The night we moved them was a beautiful evening with a full moon. We waited until evening, once the strong winds from earlier in the day had died down.
There are many benefits to moving them outside, but one of the nicest things for us is that our living room seems much bigger with the plant stands gone! Using our high tunnel for this purpose offers many benefits. I will outline some of those below.
The lighting is better once plants move to our high tunnel
The natural light that floods our high tunnel is much better than anything we can give them artificially. We see quite a bit of growth once they move to this environment, as it gives them ideal light for optimal development. They thrive here much more than they would under grow lights. In addition, we save money on our electricity bill once we shut off the grow lights.
We begin to give our plants liquid fertilizer around this time. This post explains the type of fertilizer we use that has worked well for many years. We typically wait to apply this until the plants are outside because we use a sprayer and it would be messy indoors.
Available heat units are better in the high tunnel
The heat units in our high tunnel are difficult to duplicate in the house, and we wouldn’t want to as they would be too warm to live in comfortably. It is advised to not let temperatures in a high tunnel get above 90 degrees. However, sometimes it gets warmer in ours for a short time and the tomato and pepper seedlings seem to do fine. Once the temperature rises much above 100 degrees it can start to cause them stress, so we try not to let that happen for very long.
Our goal each day is to open the doors to lower the temperatures before the plants get too hot. We keep a close eye on this, as we see major temperature shifts very quickly once the sun comes up. Temperatures can go from near freezing over 100 degrees in a just a few hours on a spring day. Therefore, it is important to watch the temperatures closely.
Different plant species react differently to warmer temperatures as well. You wouldn’t want to put a cool weather plant in a high tunnel and allow the temperature to rise very high if you want them to do well. Our peppers, tomatoes, and basil like the higher temperatures much better than say, a spinach or broccoli plant would.
It’s easier to harden off our plants in the high tunnel
Plants must be hardened before they can be transplanted in the ground. For us, this is much easier to do in a high tunnel than putting them directly outside in the open air because we have so many plants. We began to prepare them for this stage while they were in our house. We kept a fan running near them to give them enough of a breeze to begin strengthening their stems. Once they are in the high tunnel, depending on how much wind we have on a given day, we can open the doors a little or all the way. We can also choose to only open one door instead of both on either end.
This takes a few weeks and we start slowly. As the plants adapt, we gradually increase the amount of wind the plants are exposed to. After a few weeks we can open the doors on both ends and it creates a wind tunnel. This keeps the plants cooler and allows the stems to get stronger. Soon they will be ready to go in the ground.
We have only hardened our plants off in our high tunnel, but this is an excellent article on how to harden them directly outside.
We move our plants in cold temperatures
This is probably the most frustrating thing about moving our plants to our high tunnel in the spring. It is not heated so we must move them (or cover them) if the temperatures are too cold. We have done both, depending on how cold it will get overnight. We can get by with covering them if the temperature isn’t going to drop too low. It’s not worth taking a chance with covering them if we are in a freeze warning. Andrew puts all the plants on pallets. This makes them much easier to move to a more sheltered area if needed.
This is all just part of the unpredictable Spring temperatures in Iowa, but the benefits the high tunnel offers our plants makes it worth having to move them on occasion if it gets too cold for them.
