As we head towards the end of the season, it is time to start thinking about the cleanout process. Throwing out the old and preparing for the new is one of the most important components to protected production.
While this is going to look different for those in soil-based systems compared to those who are set up hydroponically, there are some key messages below that can be adapted for any producer. For those who are growing in soil, producers should consider removing plastic on spaces that are not being used for production. The lack of rainwater coming onto your tunnel soils will result in the accumulation of salts in the soil if left unchecked. One of the best ways to tackle this is to allow the snow and rain that come with the winter to run through the soil. Come growing season, this will allow for better uptake and use of supplemented nutrients, and less stress caused by buildup over time. Plastic removal can be a pain, so even doing so every few years is going to be hugely beneficial where it is not feasible to do more regularly. For more information on soil salinity in high tunnels, check out this fact sheet!
Here are a few key parts to your end-of season wrap-up:
- Removing ALL organic matter from the greenhouse, and greenhouse vacinity
- dried up leaves, old soil, dirty pots and growing supplies are perfect hiding spots for pests and disease to overwinter. Its important that you eliminate as much potential habitat and food source as possible
- Don't hesitate to do this in stages. Clean out the big stuff, and come back a second and third time to get rid of the bits and pieces that were not picked up the first few times. Vacuums and leaf blowers can be excellent tools for capturing/collecting small organic bits that seem to escape the grasps of a broom
- Do not leave piles of plant material or old soil next to your greenhouse. As much as these serve as habits inside the production space, they will do the exact same thing outside. No matter how well the inside is cleaned, if you have a major source of insects just steps away from the greenhouse...there will be problems
- Collect all old growing supplies from the year, and remove from the space for cleaning. Pots, carrier trays, pruners, clips, support stakes/string etc. should be dealt with to reduce pathogen and pest load into the new production cycle. Pots, carrier trays and pruners can all be sterilized and re-used, but be aware of the cleaning agent used here - some are going to cause more harm than good! Wooden stakes, while tempting to re-use these, cannot properly be sterilized because they are highly porous. Disease transfer from year to year from re-using stakes is possible.
- Consider swapping out ground cover! While this isn't something typically tackled on a yearly basis, following a heavy disease year it can be worth considering getting a new cover put over the ground. If you are considering this, remove the old cover before going forward with suds and sanitizer! That way your ground layer will be scrubbed back to a base layer of clean, and you can be confident that nothing is hiding out in tiny cracks and crevices throughout the old ground cover.
- Suds up the space
- Giving all growing surfaces a soapy scrub is going to grab hold of any bacterial, viral and fungal agents that are still in the space and wash them away.
- The best strategy for washing a greenhouse is to start at the top and work down - and this includes your ceiling! Failure to wash the top of the grow space creates a disease bank that can literally rain down on your future crop.
- Once you have applied your soap, give the production space a thorough rinse and allow it to air dry
- Once you have allowed the space to airdry after cleaning, it is time to bring in the big guns- Sanitizer! There are a lot of sanitizers on the market to chose from, but they do have a few things in common:
- Contact time is important. Different products have different required contact times in order to be effective. Be sure to check what the required contact time is for your product of choice, and do your best to adhere by that. Otherwise there is no guarantee that the product will sterilize to the degree that you are hoping for
- Organic matter will de-activate sterilizing agents. Any of those leaves or soil bits that got left behind will actually render your product useless.
- Consider how corrosive your cleaning agent is. Bleach is effective, but does impact the longevity of growing equipment, both for plastics and other materials.
- TEMPERATURE. Sanitizer efficacies significantly decrease at lower temperatures. While it is difficult to justify heating a protected space for cleanout, it is a key factor in maximizing your product efficacy.
Posted by: Talia Plaskett
