Greenhouses provide plants the perfect indoor growing conditions. Unfortunately, they can also be home to insect pests.
Whiteflies (figure A) suck the juices from foliage and weaken plants. To test for whitefly, tap a leaf gently. If a cloud of tiny white insects flies off and then resettles, you probably have a whitefly infestation. To get rid of them, hang yellow sticky traps near infected plants, spray with insecticidal soap according to label directions, and keep the greenhouse clean and free of fallen foliage.
Spider mites (figure B) suck the juices from tender new growth and can be a problem both indoors and out. To check for spider mites, hold a piece of white paper under a leaf, and give the leaf a good tap. If tiny rust-colored specks drop onto the paper, the plant has spider mites. Treat with insecticidal soap, or make up a solution of 1 teaspoon dishwashing liquid, 1/2 teaspoon horticultural oil and 1 quart water. Apply to the plant with a spray bottle. The next day, wash the plant with fresh water, and repeat the process until you no longer see evidence of spider mites. It may take four or five treatments to eradicate these pests. Always begin with the least toxic method of insect control. If it doesn't work, you can take stronger measures.
If you notice the presence of insects but they don't appear to have caused a major infestation, try washing plants with warm soapy water.
Gardeners often move tender plants outdoors for the summer and then back inside during winter. Here are some tips to help ease the transition for your plants:
In the spring, move plants to a protected area, such as a covered porch, before taking them to their final summer location.
Never place them in direct sun: dappled light is best.
When moving plants back inside for the winter, reverse the process. First take them to a protected outdoor area, then inside but away from heater vents and drafts.
Wash the pots to remove insect pests and dirt before bringing plants back inside.
Watering Tips: - The most common houseplant mistake is overwatering. Always check the soil on container plants before you water. The soil should be dry to the depth of the first knuckle on your index finger before you add more water.
- Avoid using tap water, which contains fluoride and chlorine that could damage delicate roots. If you must use tap water, allow it to stand overnight in a watering can before using.
- Rainwater or spring water is best. Collect rainwater in barrels for use on your indoor plants.
- Water treated by water softeners has a high salt content and isn't recommended for use on indoor plants.
- Use tepid -- not cold -- water (cold water can shock plants' roots).
- Fish-tank water is great for use on indoor plants.
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