Coles County Yard and Garden

Coles County Yard and Garden

Water for our Plants & Garden Questions for Indoor Plants

This column was written by Marsha Overton, Coles County Master Gardener.

You know the easier our lives are supposed to be the more complicated they seem. Take water for instance. We no longer have to go to the well with buckets to retrieve this precious thing. Instead all we have to do is turn on the faucet. (I must admit I never had to go to the well....and I am very glad I didn't.) For those of you who have heard, you should leave your tap water out for 24 hours so the fluoride and chlorine can dissipate before watering your plants. I wasn't really sure why they used these two additives together when discussing tap water for plants, but they do. After checking this out a little further I came up with some interesting facts.

First of all, fluoride does not dissipate and probably is not harmful to our plants. Also, chlorine hasn't proven to be a problem at all, according to a propagation manager at one our state botanical gardens. Very likely, the reason chlorine rarely causes trouble in the tap water used for plants, is that in the course of moving through the municipal system, most of it volatilizes, that is, escapes into the air in the form of gas. Chlorine just doesn't remain long, which is why it has to be added repeatedly to swimming pools. That said, please take note–some municipalities add heavier doses of chlorine, or add them closer to the end user. So, it is suggested to let your nose be your guide. If you smell chlorine go ahead and age the water–it won't hurt and besides it really is best to have lukewarm water for watering.

While I am on the subject of water, I thought I would take it a couple of steps further concerning "softened water" and "recycled water". The things that make water hard are minerals like calcium and magnesium. Water softeners remove these minerals (which plants like) by exchanging them for the sodium part of the salt (sodium chloride) that is found in the softener. Not enough sodium goes into the water to affect its taste, but there is much more than would be there naturally.

Sodium is a very active chemical. It also exchanges places with the potassium in plants cells, which is necessary for dozens of cell enzyme functions. When potassium is replaced by sodium, these functions can't happen and the plant can die. Different species have different tolerances, but eventually the sodium build-up will get to all but those that grow naturally at the seashore.

Now about "recycled water" for our plants. I am talking about water that is removed from the air by a dehumidifier. This sounds like a great idea. In fact, some indoor gardeners have suggested to "broadcast" the water. But according to several manufacturers of dehumidifiers, they do not advise re-using the water from these machines for anything. One reason for not using the water is that if you use a solvent to clean your dehumidifier then these cleaners could contain some chemicals harmful to plants.

If you want to use the water then use it on a plant to experiment only. And just to be on the safe side, do not use the water on anything you plan to eat. Well, I hope I have shed a little more light on the subject of water. I guess what kind of water to use on your plants is a lot like wondering about certain foods to eat. If in doubt, then throw it out.


Q) Can you address the question of fertilizing houseplants? Should I fertilize year-round? If so, how often? A) This question could have a lot of answers, to say the least. Fertilizing houseplants is like watering houseplants. There is no general rule, except that the average houseplant is more in danger of getting too much than getting too little. The best course if to watch each plant for changes that will signal its needs. Is it trying to put out new leaves? Do you see a suggestion of flower buds? Or is it just sitting there looking green? Plants are hungrier when they are in active growth or preparing to bloom than they are when they are resting. Unlike people, they won't automatically get bigger just because you feed them more. Most foliage houseplants do keep slowly making leaves and getting larger as long as they stay alive, but very little fertilizer is required to maintain this status quo. In spite of all this, many indoor gardeners do successfully simplify life by using a very small amount of fertilizer each time they water. Q) The tops of my houseplant pots are coated with a crust. Is this harmful? A) What you are seeing is a buildup of salts from chemical fertilizers. Although this is not harmful in itself, leaves touching the salt-coated portions will rot and fall off. The easiest way to dissolve salts from containers is to soak the pots for about 15 minutes in warm water. To prevent damage from future build-up, coat the rims with melted wax. And regularly water plants generously enough so that excessive salts are flushed out the drainage holes.

Q) I'd like to use soil from my garden for my houseplants. Will this be O.K. or do I need to do something to this soil? A) As a rule, garden soil is not practical for houseplants or seedlings because it contains insects and the pathogens that afflict plants. If you do not want to buy a commercial potting mix, which is already free of these problems, you can try pasteurizing your garden soil. To do this, sift the garden soil through your fingers to remove pebbles and twigs. Then pour it into a deep baking pan and add enough water to wet it completely. Stir thoroughly so the water is uniformly distributed. Pre-heat an oven to 180 degrees and heat the soil mixture for about 45 minutes. The procedure will kill soil-borne insects and diseases. After the soil cools, it can be prepared for houseplants: combine equal parts of soil, sand or perlite, and composted leaf mold or peat moss.

Personally, I would not go through all of this for potting soil for my houseplants. There are several different brands of good potting soil mix.

Just remember, the heavier the bag does not mean better potting soil. I always thought the heavier the bag the better it was. Right? Well, wrong. Just like bigger is not always better, neither is heavier. You can really feel a difference in the texture of the soil, also. It actually filtered down through plants right away. After talking about all this repotting, I think I might even be in the mood the repot some of my houseplants. How about you???

If you need other houseplant information, check out the Coles County Extension website at: The Horticulture and Environment icon has a link to Houseplants that will answer additional questions.

Emerald Ash Borer Teleconference

Emerald Ash Borer appears likely to eliminate all of the ash trees in North America. In many Illinois towns and cities, 20-30% of all of the trees are ashes. The beetle was first found in Illinois in 2006 in Kane and Cook Counties in northeastern Illinois. Coles County will host a teleconference with Phil Nixon, Extension Entomologist with University of Illinois Extension, to present the latest information on Emerald Ash Borer and show how to distinguish EAB from other borers that attack Ash species. Mark your calendars for Tuesday, February 13, 2007 at 1:00 p.m. To register call the Coles County Extension Office by Friday, February 9. There is a charge of $2 to cover hand-outs.

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