Cleaning up a greenhouse or growing site or structure in an effort to start a biocontrol/IPM program of pest control is most easily done in a new or empty area. If the area’s not empty, though, the same techniques outlined in this page will need to be applied in a more directed and confined fashion so as not to disrupt the existing plant material. If it is possible, segregate or remove the plant material from the areas to be cleaned. A new indoor area, or one never having seen pesticides or pests, if the floor is dirt or gravel, should probably be treated in the same way an emptied one would be treated, though not as intensively, so a differentiation will not be made in that respect. I will discuss the differences regarding indoor and outdoor areas, though. I’ll start with indoors.
A greenhouse or growth chamber is perhaps the easiest type of area to prep as the entire space can be treated. Since we’re dealing with the Green Methods, I won’t offer the easy way out: I won’t suggest you bomb the structure with some fumigant or total-release aerosol, though that is an option. If it’s your option, do try to choose something with a short residual period which allow immediate implementation biological controls, unless downtime is not a factor you’re concerned with. My suggestions for cleanup will be more manual in nature. After all, that’s part of biocontrol and IPM. I’m a hands-on, tactile person not afraid to get my hands dirty, get down in the trenches and to do things the old fashioned way. And why should I be afraid? After all, hands-on techniques tend to be very thorough.
Starting at one end of the structure, remove by hand or flame-away any and all living materials. This includes weeds and grasses and such. Then disconnect all electrical power to the structure and hose everything down (be careful not to actually get water into any motor housings, furnace components etc.). With plain water you can do a lot of good work. Wash away the old and nasty (chemicals, petroleum oils, even dirt and dust), and expose the new and fresh. Start with a clean slate, so to speak. Now go back to the starting point. With a scrub brush and soap thoroughly clean everything: benches, fan blades and housings, horizontal air flow fans, potting and work areas, even concrete floors. (If you have dirt or gravel floors soak them with the soapy water you’re using. If you have a weed barrier fabric over a dirt floor you may choose to remove it and clean it separately, or even replace it with a new fabric after the cleaning process is complete, or simply pour the soapy water through the fabric.) Rinse again with plain water when you’re through. All this rinsing and cleaning might bring up the question of toxic runoff. Well, contain it if you can — which will probably be impossible — and remember, after this, hopefully, you will no longer be adding toxic substances which can lead to a runoff problem. Now, again starting at the beginning, re-clean the area with an approved disinfecting cleaner. There are several on the market designed for this purpose. Even a solution of water and ten percent bleach will work. Rinse again.
Now that all this cleaning is done and your hands are shriveled up like prunes, let the structure air out and thoroughly dry. Don’t worry about leaving it open as pests won’t be very attracted to it now that there’s nothing in it for them to eat. If you still have plant material in the structure, you’ll have to dry it out using your fans and the cleaning process will have to stop there. If it’s possible, in other words you don’t have plant material in the structure and you don’t have to start new material right away, the next step would to seal the structure as tightly as humanly possible, leaving the power disconnected (unless heating is needed to bring up the temperature inside the structure), and let the structure bake in the sun — though be careful to avoid melting plastics, especially the poly covering, because it can get very hot. After a week or two, if you’re in an area experiencing freezing temperatures, open up the structure as much as possible to allow the areas inside to solidly freeze (do winterize the plumbing and shut off the water before doing this). When sufficiently frozen, seal it up and let it bake in the sun again. This process can be repeated as often your schedule allows. It is very beneficial. And if you close shop every year and don’t overwinter plants, it is a strongly recommended annual practice.
If your greenhouse is always in an operational state, clean things up the best you can while working around your plant material. Bomb if you have to, using a product with the shortest residual period possible. Where water, elbow grease, heating and freezing was the ticket in the situation described in the paragraph above, chemicals and, better yet, time, will be your path to transition in this case. In any scenario, try to plan all of this ahead of time. I’ve often heard frustration from growers who have gotten their hearts and minds in the right frame and their desire is very strong, only to find out upon further questioning they had just cleaned things up by using a powerful chemical with a three month residual period. If it’s possible start a biocontrol/IPM program at the beginning of a season: new year, new plants, and a new attitude.
Obviously the indoors recommendations listed previously herein are best suited to a greenhouse or similar structure. Let’s say you’re an interiorscaper, though. Then, of course, you’ll have to make some major modifications to this plan. You can, however, still clean things the best you can (probably cleaning some of the plant material directly), including pots and planters. You may even opt to switch out some of the potted plants with pest-free ones, and this can be cheaper. The removed plants can then go into an area better suited for cleaning and pest control — if an area is available, that is. Soils and planting media may also benefit from a change over or sterilization. To sterilize the media, you’ll have to bake it in an oven for about half an hour at 140 to 160°F — the warmer and longer, the better. Fortunately for interiorscapers, cleaning of plant material is often an integral part of the plant care regimen so chemical residues tend to be less of a problem. Interiorscapers then, logically speaking, should be less vulnerable to certain problems which commonly affect greenhouse growers. This allows an easier, less problematic transition. However, as it pertains to the cleaning of media, interiorscapers may not have the options mentioned above.
In the great outdoors things are a little easier as rains and winds do a lot of the cleaning for you. No more rinse, soap and rinse again; you can skip all that. You may, however, opt to give your soils a break by switching field or garden areas as part of a rotation plan. If that is not possible, due to limited space or your soils have serious problems, a summertime solarization break — not my favorite choice, rotation is — may be necessary (this is best suited to small gardens and raised beds, though). To do this simply cover the areas to be treated with a good quality four-mil clear poly, cover the edges so it doesn’t blow away or allow heat to escape by mounding surrounding soils or rocks, bricks, etc., on top of those edges, and let it stay exposed to the sun for about a month. This process will kill soil pathogens, insects, weeds, etc., at least to depth of about four inches. If pests and diseases reside below this point, turn the soil over and repeat the process. Bear in mind before going through all this trouble, garden and field plots are fairly natural and don’t necessarily benefit a great deal by sterilization as this will negatively affect beneficial microbes, bacteria and even some good insects. Like I said, rotation, in my opinion, is a far superior method of allowing the problem area a well-deserved and necessary rest. To do this plant your primary crops somewhere else for two to three seasons. In the areas slotted for a rest period it is best to plant something which will enhance to soil and allow the area to build itself back up to its full strength. You can let the area be fallow, but cover crops like buckwheat, rye, oats, alfalfa and clover may help build soils back up to their former state. The latter two crops are my favorite, they are legumes which fix airborne nitrogen and send it below, and can be perennial. The other crops mentioned should be replanted annually. Grasses and sod should be avoided as they give nothing back and deplete the soil’s available nutrients — though they do reduce compaction.
A transition to biocontrol/IPM in outdoor areas should inherently be much simpler due to the more favorable and natural conditions, weather’s positive effects and the natural occurrence of good bugs. As you may or may not realize, most of the problems encountered by growers are related to the growers’ excessive tinkering with things. In other words: if it ain’t broke, don’t fix it. If things are not too far gone outdoors, it is best to wait a month then go directly into your new way of dealing with pests. If you haven’t been using chemicals with long residual periods and don’t have really terrible pest or disease problems, you don’t even have to wait before delving into the world of the Green Methods.
Now let’s move along to part three.