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The indoor plants are ticking over, I guess. The jasmines (Jasminum sambac) have their usual winter infestation of whitefly, so I broke out the insecticidal soap a few days ago. The references specify to use soap and not detergent; being of a curious (skeptical) nature I experimented with detergent in previous years and guess what! It doesn’t work. I imagine it’s because the chemical properties are different (soap is a mixture of fat and alkali; detergent is a petrochemical byproduct).

The reason soap works on insects is because insect exoskeletons (made of chitin) are not inherently waterproof. To prevent dehydration, they exude a waxy cuticle. Soap dissolves this cuticle and the insect dries out. Detergent has a different chemical activity, which I imagine doesn’t remove the wax. Chemistry was a long time ago for me, so that’s as far as I can go without looking it up.

Anyway, in another experiment, the plant bulb did not prove to be any better than a standard incandescent bulb. The water hyacinths (Eichhornia crassipes) growing under a table lamp did just as well with either bulb. I’ve also successfully maintained tropical plants under a halogen desk lamp. Somehow this was the result I’d expected; the bulb was a 60-watt Phillips Agro-Lite bulb. Possibly a different brand might give different results. I do know that regular incandescents are not enough to raise seedlings.

Finally, I remember now why I never forced paperwhite daffodils (Narcissus tazetta) indoors since the first time. First, they flop over. Second…the smell. Oh gods the smell.

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