You should clean all or your benches, tools, (reused) pots, even irrigation lines if you have and use such equipment. It all helps.
That time of the year is here for many of you. You’re getting into the greenhouse, starting to thaw things out. You’ll be starting plants and greening the place up soon if I haven’t waited too long to write this. And hopefully my timing is good, because before you green up, be sure to clean-up. I know, I know, you are cleaning, or plan to, but I’m not talking about just organizing, sweeping, and hauling out last year’s big debris. I mean a deep cleaning, one with pest control in mind. A little prep now can pay off throughout the season.
That was Sooo Last Year
If you still have dirty pots and flats lying around from last year you need to clean all of that up. This should have been done right through the season whenever the need arose. I know, I know, it was busy. Anyway, if it needs to be done now, it needs to be done now. While you’re all it, remove any and all remaining plant debris, weeds, and spilled media. All of this material can harbor pests, weeds, pathogens, fungal spores, algae, and more. The greenhouse should be relatively empty now so do be thorough. Very thorough. You won’t get it all, but you’re not yet done, either.
Scrape Away a Layer
The floor catches it all, so the floor must be cleaned.
Concrete Floors
If you have a concrete floor in your greenhouse you’re lucky — if it’s in good shape and has good drainage, that is. You can wash it with a concrete floor cleaner, scrub it with a stiff brush, you can even power-wash it. Then you can seal it to lock out the coming season’s onslaught of everything that will fall on it. If you have cracks, there are fillers you can buy to take care of them, since you’re on a roll. But if you don’t have concrete, clean-up will be a little more difficult. It’s still doable, though, enough so to affect a change and make a difference, and quite necessary.
Dirt, Stone Dust, or Sand Floors
If you have some sort of small particle friable material like packed dirt, stone dust, or sand, you can scrape away a thin layer and actually remove it from the greenhouse. (With some planning you can have clean replacement material standing by.) Doing this will potentially remove a number of overwintering pests that moved inside at the end of the season or are year ‘round residents. This is a great solution, but only for small particle materials.
Gravel or Stone
Larger materials like gravel or stone will require a different strategy. Some clean-up, in the corners and edges, will be somewhat possible with a vacuum (with hardware cloth or something over the nozzle to prevent sucking up larger materials). The more effort you put into it, the more you’ll get out of it. Of course the option exists, as it does with the less expensive small particle materials, to literally remove a layer, but this is a more expensive and more difficult option. Moreover, unless you remove all of the gravel (and you will want to do this once or twice decade anyway), it’s not very effective. Too much will stuff fall down below the layer removed and onto the underlying weed fabric, dirt, or sand layer. Gravel and stone floors can be difficult. I don’t recommend them.
Greenhouse Cleaning Products
You should clean all or your benches, tools, (reused) pots, even irrigation lines if you have and use such equipment. It all helps. This should remove any plant pathogens that were carried over from the past season. There are a number of products available. First there are quaternary ammonium compounds. Green-Shield is one such product. Then there are hydrogen dioxides like ZeroTol and Oxidate — the latter is approved by the Organic Materials Review Institute (OMRI) [1]. There are also chlorine dioxides like Selectrocide. Lastly there is chlorine bleach and alcohol (fire danger). Organic growers will only be able to use an approved hydrogen dioxide, as mentioned above, and maybe isopropyl alcohol. Check with your certifying authority.
What’s Next?
Once everything has been cleaned up… if you have a concrete floor, you’re ready to go, if you have a friable material or stone or gravel, you might want to treat with the predatory soil-dwelling Hypoaspis miles mite or perhaps the rove beetle Atheta coriaria. These predators will stick around for a while, find anything edible that was missed, and be on the lookout for anything that might be a meal in the future. They’re a great investment. And who knows, you may see them for sale at a discount on this site soon (hint-hint).
This Season
If you’re one of those who is just getting around to getting rid of last year’s big chunks, this year clean up as you go. If you do, you will benefit not only from running a clean operation, but you can also do a big clean-up at season’s end, while it’s still warm for many growers. And if it’s still warm, you might be able to do a greenhouse bake-out. This is worth doing if you can.
Resource: Some of the information in this article was derived from the U-Mass Fact Sheet: Cleaning and Disinfecting the Greenhouse.
Hypos On Sale - GreenMethods.com responds:
Posted: February 1st, 2008 at 6:35 pm →
[…] We hinted in our “Clean Up Before You Green Up” blog post that this special was coming and we weren’t leading you down a primrose path. The sale is now: Our famous predatory mite, Hypoaspis miles, is now on sale at a significant savings below our already low price so this is a great time to stock up, but this sale won’t last for ever. This special is good through Feb. 8, 2008. […]