I give my houseplants a shower in mid-summer and they love it. Take the plants outside on a cool evening and spray them with a very diluted mixture of Ivory Liquid and your favorite seaweed plant food. Be sure to spray well under the leaves to dislodge mites and other critters. The next morning bring in your shiny, clean plants and enjoy. Repeat the process in September to get your houseplants ready for the long winter.
If you have aphids on your outdoor plants, you can use plain water and a sharp spray from your hose to dislodge them. If the aphids are on flower buds, support the bud in one hand and spray with the other. Good luck!