Gardenias - Indoor pest treatment

Last spring I purchased a beautiful "everblooming" gardenia grown as a standard. It did bloom all summer on my deck, receiving part sun with shade in the afternoon. I've moved it into my new sunroom where it continues to look great, and is even blooming, with more buds forming. When I bought it, I asked the garden shop owner for his advice on overwintering it in my sunroom, knowing that it was prone to scale, etc. when grown indoors. He gave me what seemed to be the strangest advice. He said, in addition to never letting it dry out, to weekly mist it with straight 70% isopropyl alcohol to kill any pests. I even had him repeat his advice to make sure I heard him correctly.
Well, so far, I've misted it twice since the first appearance of cottony cushion scale on the new growth tips. It hasn't seemed to hurt the gardenia at all, and the soft scale does seem to be knocked out. I was wondering if anybody has ever heard of this preventative treatment or has ever used straight isopropyl alcohol on plants. I could have sworn it was going to kill the plant!

Alcohol isn't good for plants--if I have mealy bugs I'll take a q-tip dipped in alcohol and use it to rub the mealies off since you don't have a ton of alcohol coming in contact with the plant when you do that, but personally I wouldn't recommend spraying alcohol all over a plant. Probably why it hasn't hurt anything is that alcohol evaporates very quickly and the small little drops you have when you mist the plant help it to evaporate fast so it doesn't have time to damage the plant, although I'm surprised in that case that it would kill the scale.

I regularly use a 50/50 mix of tap water & 70% isopropyl (rubbing) alcohol on any plants that exhibit any type of infestation. I often recommend:

1 pint HOT water
1 pint isopropyl (rubbing) alcohol - 70%
1 teaspoon cold-pressed neem oil
3 drops of Murphy's oil soap

In a quart container with a spritzer head, mix hot water, neem, and soap - shake well. Add alcohol & shake. Spritz entire plant while shaking the container frequently to keep the neem oil mixed and being sure to cover all surfaces, including undersides of leaves & leaf axils (crotches).

The neem acts slowly and has little in the way of immediate knockdown (knockdown is rapid death of the insects), which the alcohol does a very good job of providing. Use it all up or make a smaller batch - it doesn't store well.

Al

Thanks for the feedback on your experience. On second examination, sure the little buggers were mealybugs, not soft scale. Regardless, no harm so far. Tapla: my neem oil instructions say to not use neem on gardenias or palms, but I have anyway. So far, so good. I had used the neem first on the gardenia, but also decided to use the alcohol spritz. I'll keep you posted!

I wouldn't go as far as to say that the specific product cold-pressed neem oil won't harm some plants, but I can say that I've yet to find a plant that doesn't tolerate it very well. I think where many problems occur is in the fact that a high number of products use other insecticides along with the neem, and various vehicles to deliver neem oil emulsions. I've drawn the conclusion (for my own purposes) that it's likely the 'other' ingredients in these concoctions that that create the complications. Azadirachtin is the ingredient in neem that makes it so valuable in combating insects - especially future generations, and extraction methods other than cold-pressing destroy or greatly reduce the effectiveness of this naturally occurring bio-compound. That's probably why many people aren't as impressed with the effectiveness of what they think of as neem oil as I am - they are using a product labeled to indicate it contains neem, but the effectiveness of the azadirachtin has been compromised or altogether negated.

Al

Hey is this the recipe from your comment on the new Garden Blog article? I copied and pasted into my own blog so I'll have it close incase any bugs get my winter Morning Glories. Thank you for the recipe and the information.

How do you feel about Systemic Insect Pest control as a preventative measure?

I tend to embrace the IPM approach and will tolerate the presence of a reasonable level of marauders when they aren't numerous enough to be causing a noticeable decline in the vitality of my plant(s). This approach pretty much stays my hand from reaching for the chemicals every time I see a 'bug'. ;o) I do use systemics when appropriate, especially for scale, 'neem oil' being one of them. Yes, neem oil works systemically too, and is effective in the plant at extremely low concentrations.

As I consider the prophylactic use of any insecticide, including systemics, I guess I have to say that about the only compound that fits that description for me is neem oil. I over-winter around 100 tropical plants (most are normally grown as houseplants, but my focus is on bonsai) under lights in my basement. About 2 weeks before bring them in, I apply neem oil - then again a day or two before I bring them in. Normally these applications keep insect levels in check all winter, though I may see some scale or mite populations appearing toward winter's tail. If it gets too bad, I'll do a neem application & hold out until I get the plants outdoors where the increase in the plant's metabolism and thus natural defenses, along with the increase in beneficial predators, usually completely eliminates the trouble.

The bio-compounds plants use to repel plants are a by-product of the plant's metabolism. Plants with high energy reserves and plants growing with good vitality are much better protected 'naturally' from insect predation, which is why plants in low light and those that are just limping along are far more likely to be troubled by insects. I very often diagnose the occurrence of insect infestations as the end product of poor cultural conditions, and the greatest, most frequent offender is a poor soil.

Al

This message was edited Dec 10, 2008 4:12 PM

that was just what I was looking for and sounds like from the right person. I'm working on creating ideal conditions in a grow room with alot of windows and a big HPS light. I want tropical hibiscus, and I want to try some Clematis indoors but they're expensive so I want to make sure I know how to protect them before I buy 'em ya know? So what brand of NEEM is the best? I have a product I just bought from the Safer Company called BioNEEM. you ever hear of it?

My Dad kept many houseplants and for a country guy, he did a fantastic job. He swore by the method of changing the top few inches of soil now and again.and huge east facing windows. I doubt he used Neem, but maybe. I'm an outdoor gardener mostly but am sick of winter already and from experience with indoor morning glories I think I have to learn which bugs are which and know how to have the best conditions I can provide before I spend alot of money!

Thanks so much Al.

~Shawna

I use and have had very good results with cold-pressed neem oil by/from Dyna-Gro.

The top few inches of the soil are not what gets you in trouble. It's the lower few inches that support perched water in the container that generally create the problem as soils age & break down, becoming water retentive & lacking in aeration.

Good luck - Merry Christmas. ;o)

Al