This post is mostly for amateur plant murderers like myself who hope to someday become semi-pro plant nurturers.
In most climates wherein the winters require indoor heating, the air inside a home or office often becomes so dry that tender and tropical houseplants turn do nothing but whine all winter. This is (hopefully) why my palms and boston ferns -which look so good during the Chicago summers- look like crap when they come indoors for winter. In your tropicals, you too may notice the soil drying out faster, the edges of your plants turning brown, leaves turning dry and crispy or dropping off altogether, plants wilting sadly, or even outbreaks of pests that love dry conditions such as the dreaded spider-mite. Lack of humidity can be expediently solved by moving your plants and your own frozen, miserable ass to southern California post haste. If this is out of the question (as it is for me) then you might try humidifiers, pebble-trays, and collecting your plants into drip-trays.
Problem: You have no humidifiers, pebble-trays, drip-trays, or $ to spend on said items.
Answer: Fear not! Get that leftover takeout from the fridge and finish eating it while you read.
Perhaps you are like me; you love houseplants but find yourself too strapped for cash or just too lazy to grab a few plastic drip-trays from your local greenhouse when you are waiting at the register, even though they're only sixty cents or something. Maybe you don't even buy greenhouse plants and you simply make your own home garden from cuttings and collected seed (which is awesome, and please send me pictures). In any case, if you don't have drip-trays, then when you water your plants, soiled water leaks out everywhere. I have this problem all the time. See this photo:
No drip-tray here (this is an Aloe "Harlanii", by the way, an amazing variegated cultivar that I picked up at Ted's Greenhouse in Tinley Park, IL). The water will run right through the drainage holes as per common sense. A proper pot must have drainage holes at the bottom to release extra water and thus prevent root rot (there is also some debate as to whether plastic pots are ever a suitable substitute for unglazed ceramic, but that's another subject). Oftentimes, to improve a plant's aesthetic, plastic pots are placed within attractive glazed pots (cache pots), which serves a second function by providing a safe space for water to leak from the primary pot. A drip-tray can be used in place of a cache pot, or to simply protect the inside of the cache pot from soil. Furthermore, grouping several plants together on a drip-tray will allow them to share their humidity.
Caveat: never allow houseplants to sit in standing water, in a group or otherwise. When you water your plants, empty the drip-trays of any remaining water after about ten minutes. Leaving it in there will not help with humidity; it may in point of fact over-saturate the soil and cause the roots to rot. Also, use filtered water in this situation whenever possible. More on how to filter water inexpensively at home will follow in future posts.
For plants that need extra humidity (small palms, ficus benjamina, etc.) a drip-tray can be converted into a pebble-tray. It's easy. You know that gravel driveway a few blocks from your apartment? Or that lava-rock landscaping outside the library? Go steal a bunch of that stuff and wash it in hot water. Put it in your trays. Pour some water over it (not enough to cover it completely or your pot will be sitting in it, which we know is bad). Place your pot on top of the rocks. As the water evaporates in the indoor heat, the plant will take it right up through its leaves as humidity.
For plants that need extra extra humidity (most ferns) unfortunately you're really going to need a humidifier. I myself have three... yes three... which run 24 hours a day. I also keep three radiator humidifiers constantly filled. If you don't want to buy a humidifier, don't fret. People chuck those bad boys away on craigslist.org all the time. Just check the free section. The super ultra mondo tender tropicals such as the maidenhair ferns or club mosses are just not meant for traditional indoor culture, because they often require humidity in excess of 50%. You don't want to grow them; they are spoiled, tantrum-throwing, suicidal bastards. If you just can't resist them (like me), you'll either need a terrarium or a misting schedule. Both of these require their own posts... misting in particular can be anywhere from useless to harmful unless conditions are right.
So, back to the pebble-trays and drip-trays. Are you done eating your takeout? You know, those leftover chicken kebabs from that awesome Turkish place that you suspect has a cockroach problem? Don't think about that, now or ever. Just give in to those amazing kebabs and save the container. Perhaps your layout looks like mine:
As you can see, something is rotten in the state of Denmark, as they say. If I had to guess, I'd say it's the economy, my bachelor of arts degree, and possibly that can of chocolate frosting on the middle shelf that I keep meaning to throw away (it's kind of a substitute for peanut butter... right?). Other items include a cold mug of coffee, a handle of gin, my leftovers, and a can of cat food. It's prescription stuff for the cats, I swear. We have not gone totally Grey Gardens around here.
Anyway! Get that leftover tray and give it a little wash! Don't go nuts... this is garbage we're washing, after all, and probably conserving fresh water is more important than recycling. Just get the food and soap out... neither of those things would be great for your plant to absorb.
Ta da! Both the lid and bottom can be a drip-tray or pebble-tray. Use them underneath plants to catch run off, or fill with pebbles and group plants inside of them to increase humidity. In the above photo I have my succulents grouped in a tray. These plants don't require enough humidity to warrant pebbles, but grouping them will make watering a lot easier. And finally:
Fill the foil bottoms with water and put them on your radiators to serve as little humidifiers! This is an old trick of course, but your plants will be thrilled by your ingenuity nonetheless. You'll be surprised at how much water will evaporate from these trays every day. You need not use filtered water in this instance; tap is fine. The foil will get hot, but it won't catch fire, I swear. Alternatives to this that I have tried are metal bread pans and pie pans, but using leftover containers allows me to keep my kitchen items in the kitchen. Also, salt buildup from tap water can be difficult to remove from kitchen pans.
I hope this was helpful, and will allow you to keep something alive and happy!