Let it Breathe!

---

During the winter months we do our best to button up the high tunnel nice and tight and cover the plants with row covers to give as much protection from the cold as possible. Funny enough the flip side to all this effort is that is can be equally detrimental to the crops we are trying to protect. Inside the sealed up tunnel and underneath those blankets resides the perfect conditions for an outbreak of disease- most notably fungi and mildew. The combination of high humidity and stagnant air coupled with spikes of warmth on sunny days is just what these less-than-beneficial microorganisms need to multiply. What a catch-22 eh?

Ironically, one of the best things we can do to pre-emptively to avoid disease issues is remove the very covers being used to protect the plants. In addition, opening the peak vents of the tunnel is the best way to relieve some of the humidity and allow for some cross ventilation, i.e. bring in some fresh air. The ideal kind of days we are looking for are when the sun is out and the inside temps are above 50 degrees. If sunny days are few and far between, take advantage of those warm spells (if there are any) where outside temps are above 32 degrees.  The last few week have been ideal for ventilation with some sunny days and even temps in the upper 30's. I have removed the covers and three times thus far since Christmas. I will open and close the peak vents daily but leave the row covers off until the weather forecast shows daytime temps dropping below 32 degrees again. Some commercial growers in Northern climates are even going so far as to leave their peak vents cracked all winter. The jury is still out on how much or how little to ventilate during the heart of winter. The main thing is to at least make a point of doing so at least once or twice during the months of January and February.

-Todd

---