Grow your own mosquito repellent

[Guest guest]

Grow your own mosquito repellent

 

The news is full of horror stories, including the spread of the West

Nile Virus by mosquitoes. At the same time, a news item landed on my

desk that seems to promise a simple, natural way to fend off the

little buggers.

 

Last year, several members of the Iowa State University Department of

Entomology presented the results of a study on common catnip. Among

their conclusions was the fact that an essential oil in catnip is 10

times more effective at repelling mosquitoes than potent chemicals

such as DEET.

 

DEET is currently the most common active ingredient in commercial

mosquito and bug repellents. Unfortunately, many studies indicate

that DEET is also a dangerous chemical for humans, especially

children. A study carried out at Duke University Medical Center

revealed that DEET can cause brain-cell death and may trigger

behavioral changes indicative of neurological damage in rats after

frequent or prolonged use.

 

In an effort to find a safer alternative, the scientists investigated

several plant essential oils that were commonly recommended as insect

repellents by organic gardeners. Catnip ranks high on the list of

natural bug-busters and evidently with good reason. In the Iowa

study, the researchers noted that small doses of catnip oil were at

least as effective at repelling mosquitoes as 10 times larger doses

of DEET (which was used at typical recommended application rates for

commercial products).

 

While the researchers don't know why mosquitoes don't like catnip

oil, they do know a good thing when they see it. Recently, the Iowa

State University Research Foundation applied for a patent for the use

of catnip essential oils as compounds. Within a few years, we'll

probably see many safe, non-toxic mosquito repellents on the market.

 

In the meantime, why not grow some mosquito repellent of your own? If

you have a sunny, well-drained patch of lean garden soil, try

planting some catnip. The plant you need is a perennial herb called

Nepeta cataria. Closely related to ornamental catmint, or Nepeta

faassenii (or N. mussinii), catnip is generally grown as a cat-

pleasing or medicinal tea herb rather than for its looks.

 

Catnip is far from ugly, but its gentle blue flowers are definitely

out-produced by its masses of softly hairy, gray-green foliage. Like

most herbs, it prefers well-drained soil and plenty of sunlight. If

you garden on heavy clay, you may succeed better with catnip and

other herbs if you give them a mounded bed or grow them on a slope to

improve winter drainage.

 

The first year you plant catnip, you may need to water it a time or

two, especially if next summer is as hot and dry as this one has

been. However, fall-planted herbs, including catnip, often need very

little water the following summer. Fall and winter rains can help

plants create deep, strong root systems that increase the natural

drought resistance of catnip and many other herbs.

 

Don't feed your fall-planted herbs, but do mix some compost into

their planting soil. A mix of half compost, half native soil is

usually just right. Top off the soil with a light blanket of compost

(2-3 inches) to help feed those actively growing roots through the

cool months.

 

Even in spring, don't feed your herbs with anything but compost, or

at most a mild all-purpose organic fertilizer such as Whitney Farms 5-

5-5. Adding too much fertilizer can cause lush overgrowth in many

herbs, leading to dilute or low-quality essential oil production. In

some cases, herbs such as creeping thymes can be killed by commercial

fertilizers, so when in doubt, use only a very mild fertilizer and

apply it at half the suggested application rate.

 

This summer, I experimented with making both catnip vinegar spritzers

and catnip infused oils. Both did a fine job of keeping mosquitoes

and no-see-ums at bay during our warm summer evenings. If you would

like to try this yourself, here are the simple recipes I used:

 

 

CATNIP MOSQUITO SPRITZ

MAKES ABOUT 3 CUPS

 

2 cups catnip, stemmed

3-4 cups mild rice vinegar

 

Rinse herbs, roll lightly with a rolling pin, then place them in a

clean quart jar and cover with vinegar. Seal jar and store in a dark

cupboard for two weeks.

 

Shake jar lightly every day or so for two weeks. Strain into a clean

jar, seal and refrigerate for up to 6 months unused.

 

To use, spritz on exposed skin and around outdoor dining area.

 

CATNIP AND ROSEMARY MOSQUITO CHASING OIL

MAKES ABOUT 2 CUPS.

 

2 cups catnip, stemmed

1 cup rosemary, cut in 6-inch sprigs

2 cups grapeseed oil or any light body-care oil

 

Roll herbs lightly with a rolling pin and pack into a clean jar.

Cover with oil, seal jar and place in a cool, dark cupboard for two

weeks.

 

Shake jar lightly every day or so for two weeks. Strain into a clean

jar, seal and refrigerate for up to 8 months unused.

 

To use, rub on exposed skin.

 

Ann Lovejoy, a free-lance garden and food writer, can be reached via

mail at: 9010 Miller Road N.E., Bainbridge Island, WA 98110. Her

latest books are " Ann Lovejoy's Organic Design School: A Guide to

Creating Your Own Beautiful, Easy-Care Garden " (Rodale, 280 pages,

$35) and " The Sage Garden: Flower and Foliage for Health and Beauty "

(Chronicle Books, 144 pages, $17.95).