Thursday, March 26, 2015

Winter Houseplant Woes

~ Jessica S. Herwick
When the weather makes outdoor gardening impossible, like many of you out there, I keep a small selection of edibles and ornamentals in the bay window of my Manayunk apartment, where I also cluster my kitchen herbs and houseplants to survive the winter. Indoor gardening requires a slightly different point of view.  You don’t have to worry about pests like squashbugs, finding their way into your zucchini patch.  But, there are a few stealthy intruders out there that can survive happily in both your outside and indoor garden projects, like mites, aphids and whiteflies – and if those whiteflies find their way into your houseplants, you don’t have the benefit of natural predators like birds swooping in to snack on the insects.  The management is all up to you. 

It happens to the best of us.  No matter how diligently you prepare your indoor garden, even the best of practices cannot prevent Mother Nature from creeping in and having her way one hundred percent of the time.  Especially inside.  I follow most of the basic preventative practices when growing indoors. Water less.  The plants aren’t as thirsty and the dry soil helps prevent a number of pests, molds and fungi from setting in. Feed less, and more naturally.  Avoid tap water.  Mist plants.  Keep an eye out for invaders.  Put out traps before you see a pest.  Most importantly, keep careful watch over your favorites!  Somehow, these insects and arachnids know which plants you hold most dear.  This year, they chose my 28-month-long project, the avocados I’ve been growing from discarded seed.  I have raised several and they function happily as houseplants, filtering the stuffy apartment air and keeping me occupied during snowstorms.
I thought my precautionary tasks had proven successful and was basking in my pest-free glory… until I saw the holes, the small ½” holes peeking through the soil surface of my largest and oldest of the avocado collection.  The holes were too perfect to have appeared as a result of watering, and I hadn’t been sticking my fingers in the soil, although that’s how it looked.  The plant stood strong, no visible signs of stress or damage.  I scratched my head, snapped a photo for future research, and went on about my task – being sure to pinch off the soil surface holes, hoping to force the pest to reemerge by closing off the tunnels. I should've known better, done more.  But I didn't, and I paid the price.
Two days later I had to pack up and leave town for a week.  The pest most definitely returned in my absence.  Arriving back home 6 days later, the holes were back and the avocado had been stripped.  EVERY SINGLE LEAF had either fallen or been clipped off.  This meant war.  I removed the plant in its entirety from the container to reveal dozens of well-fed beetle grubs enjoying the tender roots of what was a thriving 2 year old avocado sapling just a week ago.

Suddenly everything made sense! 

Remembering the Japanese Beetle, who made its way into my apartment back in August, I knew I'd been defeated.  I didn’t kill it because I’m a softie, and try not to kill every bug that intrudes in my home.  I didn’t chase it outside again, because I didn’t want to send a Japanese Beetle into my back yard garden, or my lawn to breed.  Instead, I chose to endure her buzzing and kept her captive in my entryway.  Little did I know that this perspicacious little beetle was cozying up under my avocado tree to lay her eggs, but the proof was in the larva.  Oh, so many larva!  I'm sorry, Mama Beetle.  I plucked them out and fed them to the birds. 

After a good rinsing, a new pot and some freshly purchased premixed potting medium, the avocado is now replanted and starting to show new signs of life.  I haven’t given up, especially not so close to Spring!  But it’s going to be an uphill battle. 
Although you may not be able to prevent a sneaky
beetle from laying her eggs in your plantlings, there are a few tricks you can make at home and keep on hand to manage pests that creep into your houseplants from the garden, back porch or that hole in the window screen you’ve been meaning to fix.  Some will even work outside in the garden. I keep all of the following materials and ingredients handy in my plant pantry, along with a few clean spray bottles, for plant emergencies.  They happen more often than you'd think!

Management Method

Who/What it Manages

How to DIY

Horticultural (Insecticidal) Soap

Fungus Gnats, Whiteflies, Mealybugs, Aphids, Spider Mites

(soft bodied insects)

Using original Dawn brand or Liquid Joy liquid soap only (nothing with additional power or chemicals):

Combine 1 cup of vegetable oil with 1tbs liquid soap.  Mix well.

Dilute the mixture by combining 2tsps of the oil/soap solution per 1 cup warm (filtered) water and put into a spray bottle.  Mix only what you’ll use in that day.  Do not store. Spray leaves above and below.  Shade for 24 hours after treatment to prevent burn. 

! Commercial soap sprays are effective and if you read the label, you can find non-chemical based sprays that are premixed and have a longer shelf life.

Yellow “Sticky Traps”

Whitefly, aphids, thrips, leafhoppers, moths, fruit flies, fungus gnats

Use yellow poster board or color an index card with yellow marker.  Cut into 1”x3” pieces.  Fold in half around a toothpick.  Secure (I use glue stick) Paint with honey or petroleum jelly on both sides of flag.  Push toothpick into soil.  Insects will stick and die.  Replace when there’s more full space than empty space on card. 

Bury Garlic Bulbs

Burying a piece of Mother Nature’s natural insect repellent!  Burying garlic, is a Farmer’s Almanac-style trick to eradicate pests from houseplants.  Garlic is a natural repellent to large numbers of soil & leaf loving pests.  Too many to list.  

Using one clove of garlic per pot, bury the clove into the soil about halfway.  If garlic begins to sprout, pull and transplant in garden then replace or allow to grow, trimming back the green shoots.  Replace monthly for best effects.  You can use the garlic clove with or without the skin.

Apple Cider Vinegar Trap

Fruit flies, fungus gnats

In a small container (I use a half-pint jar) fill with apple cider vinegar, cover tightly with plastic wrap and secure (I screw the jar rim over the plastic wrap but you can use rubber bands or tape)  Poke small holes in top of plastic wrap and place near the most insect activity.  Insects get in but can’t get out.  Replace every 2 weeks, every 1 week in humid summer weather.

Touch with Rubbing Alcohol

(some say rubbing with a banana peel works too, but I’ve never tried it!)

Spider Mites, aphids

Dip a cotton ball or swab into a small dish of rubbing alcohol and lightly rub directly along plant stem and undersides of leaves where you see mite activity.

Larger Scale Wash: Dip cloth into rubbing alcohol and lightly rub the entire plant.  You can dilute with water for very delicate plants.

DO NOT NEED MUCH!  Lightly coat surface.  Do not pour or create dripping.  Shade for 24 hours after treatment.

Submerge, Rinse & Repot

(The old college try)

A last ditch effort to rescue a plant from any pest, roots to tip of stem.

If a plant is completely infested, pulling the plant from the pot and shaking off all excess soil and submerging the entire plant in room temperature water for up to 15 minutes will send many of the pests looking for higher ground and they will “float” away.  Don’t be afraid to gently wipe the stems and corners to “bathe” the plant. Follow with a good rinsing and wiping of leaves then repot in clean potting mix. Follow up with a preventative treatment to keep potential eggs or stragglers from creating a new brood.

Removal and Disposal

(The last resort)

Any Pest

Sometimes the insects win, and in order to save the rest of your collection, a badly infected houseplant with severe damage that has not responded to your methods for management should be discarded (not in your compost bin where they can multiply).


Philadelphia Master Gardeners Horticultural Hotline ONLINE information: 
The Horticulture Hotline (HortLine) of the Penn State Extension Philadelphia Master Gardeners is a free service for residents of Philadelphia. Master Gardeners are ready to answer questions pertaining to: selecting vegetables, ornamental plants, pesticides, soil, plant and pest identification, pruning, compost, mulch, insect control, plant diseases, canning garden produce, food safety, and more!  If we cannot answer the question ourselves we will refer it to the Penn State University Hotline.   To contact the Philadelphia HortLine Online:         
     E-mail with "Hortline" in the subject line
     Please give your question, name and contact phone number. Include photos!

 Penn State Extension Juniata County Publication about Houseplant Pest Management

Houseplant Growing Tips and Pest Management Home Remedies

Organic Home Remedies for Pests from Organic Gardening Online

Good Guide for Controlling Aphids on Houseplants

Quick and Easy Resources for Growing Avocado Basics

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