The Houseplant Guide: WATER (TheMondayGarden.com)

Eco-gardening is at its best in The Monday Garden
March 7, 2004, Issue 102

The Houseplant Guide: WATER

Happy Spring! This week, the birds sang the spring song, and the tree branches lost the winter gray, so regardless of the calendar, it�s spring. Another sign of spring is Kevin�s orchid blooming in my living room window (see Issue 53 )

picture: Behind Kevin�s orchid is a young coralberry in training, a blond Boston fern, and a peace lily (spathiphyllum).

As all faithful �Monday Garden� readers know, over-watering is the number one houseplant killer and under-watering is number two. When it comes to air and water, it�s easier to be an air-breathing human or a water-breathing fish than a plant. Plants need to breathe BOTH air and water through their roots. When too wet for too long, plant roots drown like a human. When too dry, they shrivel up like a fish.

Picture: rock found in Stamford area in my bookshelves, top view

This issue is about watering houseplants but since this is a pro-choice-in-life-style publication, I�m also including a water-less rock garden.

WHEN TO WATER: Here�s the easy part: start with the idea that most plants want to be watered really well when they�re watered. If you don�t wet all of the soil, the roots won�t spread out. So you need to see water coming out the bottom of the pot (or dunk the whole pot in a bucket) BUT you can�t let the plant sit in water. Humans can go 2 to 3 minutes under water; plant roots don�t like over 15 to 30 minutes. The easiest way to get it right is to put pebbles or other drainage material under the pot so the water which drains out isn�t touching the bottom of the pot.

Now, here�s the tricky part: when to water next? Some plants, like Kevin�s orchid and the Boston fern should get nearly dried out between waterings; others like the coralberry and the peace lily, need to stay �evenly moist�. Other than cacti in winter, few plants should go more than a week without watering. And other than bonsai, few should be watered more than twice a week. So check new plants daily. If it dries out too quickly, move it into a slightly larger pot. If the plant�s not ready for watering in a week, either your pot�s too big or it�s not draining properly; either way, the roots will rot from the excess water.

The other tricky part: how can you tell the plant�s dry enough? �Evenly moist� plants should be watered once the soil surface looks dry; �pretty dry� plants should be watered when the soil�s dry down an inch or so depending on pot size. �Very dry� means almost the whole pot. Stick your finger down in the soil or use a water meter. You can also get to know the difference in weight of your pots when they�re dry.

WATCH THE LEAVES

� DROOPING OR SHRIVELING means not enough water is getting to the leaves, either because the plant needs water or the roots are damaged.

� BROWN TIPS mean dead root tips � could be too small a pot or not enough water (spider plants like it this way). Also could be chemical poisoning (see below).

� YELLOW LEAVES can be too much or too little water, or natural aging (if it�s the bottom leaves), so you need to think through the plant and what you�re doing. (If it�s a pathos, yellow is probably over watering.)

WATERING TOOLS

I�ve tried most houseplant watering devices on the market and the good news is cheap and simple works best. Better yet, so does recycling. For larger plants, use a recycled gallon water or milk jug. For medium size, a used water bottle with a �sipping top� is prefect to keep the drips off the furniture but deliver the water fast. For tiny plants, try a needle-nose squeeze bottle from the beauty supply store. You need a long-spouted watering can only if there�s a long reach to get to the plant or if it makes you feel good.

CHEMICALS

If a plant�s slowly declining for no good reason, chances are it�s being chemically poisoned by chlorine, wrong-PH water, or fertilizer build up.

� Many plants are sensitive to the chlorine in tap water so leave the water out overnight.

� Other than flowering plants known to need a lot of fertilizer (e.g abutilon); limit fertilizer to once a month or once a quarter. Dilute twice the recommended amount and don�t use during dormancy.

� Test your water�s PH with a cheap kit from the pet fish store. Most houseplants like medium or slightly acid PH. A drop or two of vinegar will increase acidity.

� My city water contains enough minerals to turn the white laundry gray, so I use filtered water for the more delicate plants.

(If the plant�s near a gas stove, it could be gas poisoning. African violets, e.g., hate gas.)

EMERGENCY FIRST AID

UNDER-WATERING: If the plant is in a severe faint, submerge the whole plant in cool water, and leave it under water until the leaves perk up. If the plant�s too big to submerge, mist the leaves and wrap them in plastic. This can be overnight if necessary; but if the plant�s not looking significantly bettering the A.M., it�s a goner. Try to save cuttings.

OVER-WATERING: Turn the plant out of the pot, wrap the root ball in a towel, and let it drain overnight. If the roots are severely damaged, start over with whatever cuttings you can salvage.

CHEMICAL PIOSONING: If you suspect mild chemical poisoning, repot (gently) with fresh soil. Chemical salt build-up from fertilizers and hard water can be counteracted a bit by submerging the pot in fresh water for a half-hour every few months. Let dry before watering again. Severe chemical poisoning (e.g accidentally doubling the fertilizer) is fatal.

picture: from my plant collection. Marantas (pray plant family) hate chlorine and need to be watered less when dormant. They love water directly on their leaves; it deters spider mites and improves the color.