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Make sure to water your plants regularly during dry weather. Protect your plants from frost. Don't use nitrogen manures or fertilizers. Feed the carnations with water-soluble fertilizers every two weeks.
Perpetual carnations can be encouraged to flower again by making sure they are watered during dry weather. This means watering them about every 5-7 days through the summer or perhaps every 3 days in very dry, hot weather. Also give your carnations regular feeds, pinch the stems and remove the withered flower heads. It's important to protect perpetual flowering carnations from frost. You can grow them under glass or in a polytunnel, but it's vital to keep them above 45F so you may need a source of heat, even in a greenhouse. Of course, you can also grow them as house plants. Avoid using manure or high-nitrogen fertilizers for carnations, as they won't bloom as well. Also keep in mind that you should never mulch carnation plants. If planted outside, you should add lime to the soil to improve the alkalinity, and use a fertilizer that isn't too high in nitrogen relative to other components, such as potash (potassium) and phosphorus. During the growing season carnations will need feeding regularly about once every two weeks with a weak solution of water-soluble fertilizer. Avoid slow release fertilizers or ones labeled 'granular'. These release nutrients too slowly to be of much use during the growing season.