We built this indoor "garden" in our office as a prank for one of our employees who was out for a stint. It was only meant to be temporary, however we have all grown a liking to it.
We ended up planting English Ivy with some Winter Creeper mixed in. Also we used some Miracle Grow planting soil.
However, the problem is it has seemed to develop little flies in and around the soil/plants.
Is there anything we can spray the plants with in order to reduce these flies?
I believe they are springtails. The definitive identification is whether they fly. If they jump around when the soil is watered: springtails. If they fly into your face or to the window: fungus gnats. If they are white and fly when disturbed they are whitefly.
While the first two are annoying control can be as simple as keeping things dryer. Whitefly are another matter and control can best be accomplished by physically removing the plants they are living on. You don't really want to be spraying anything in your office where everyone works. Even soap and water leave a film on items located close by if it is sprayed on.
I agree that the set up you have appears to lack drainage or an appropriate depth of soil. I don't think you have a viable set up for the long run.
Although I really like indoor plants, in my honest opinion, they have no way to prevent pests.
Most pests are attracted by wet environments. If your soil is constantly wet, I bet there will be flies. If the soil contains organic substance, there will be other bugs too.
I can't see if you have a tray under the container. If there isn't a tray to hold the excess water, you can't release the excess water. And if there is a tray, you should remove the water from it regularly.
Second, you may review your soil. You should buy soil that comes in a loose shape, instead of a black soil block. For example, I always use the following kind of soil if I don't want bugs in my soil:
It is free of bugs and it contains a fair amount of perlite and vermiculite, which helps to improve drainage. Thus it is good to prevent fly-like creatures. If you don't know which type of soil should you buy in the shop, you can check the soil made for African Violets. They have higher standards to regulate the property of the soil. Check this.
Lastly, I don't recommend using such a big container because it is harder to maintain. You may consider using individual pots.
If it looks like these, then it's whitefly.
We've always had good luck with a very simple method of control for whiteflies - just move the plants outside for a few days. Whiteflies don't like sun, wind, rain - they like indoors. Also, there are a lot of things outdoors that like whiteflies - ants, ladybugs, etc. I don't know if an outdoor excursion is feasible in your case, with this big oddly-shaped tray.
Whiteflies will eventually spread to every other plant in the room -maybe even to other rooms, too.
You can also slow them down with insecticidal soap which is relatively non-toxic. If you and your co-workers don't care about toxicity (?!), you might also consider systemic granules, which is probably the most reliable control.
The gnats eat fungus which develops in overly moist soil. Get rid of the fungus, get rid of the gnats. Get some neem oil and spray the soil wit a solution of it. Subsequently, try to water the plants less to cut down on the moisture level at the surface.
get some or bum some cigarettes. sprinkle tobacco on the soil. when you water the nicotine will kill the flies and eggs.
