• Phoenix palm plants are often grown indoors in cold climates.Hemera Technologies/PhotoObjects.net/Getty Images
  
  Phoenix is a genus of plants that include many different types of palm species. Some species of Phoenix palms are used as indoor plants, where they can be grown with just a bit of care. Outdoor Phoenix palms can include species like the medjool date palm that produces edible fruit, or the Canary Island date palm, which can reach 50 feet tall. Fertilizing Phoenix palms with nitrogen fertilizer in winter depends upon certain criteria.
  
  

Outdoor Phoenix Palm Plants

• Phoenix palms are often grown as landscape plants because of the variety of sizes and shapes. Like all palms, Phoenix plants need nitrogen to grow healthy leaves and cell structures. However, palms also require high amounts of potassium and magnesium, according to the University of Florida. These are best given in slow-release form to provide nutrients in an ongoing manner. Palms also need boron, calcium, manganese, copper and zinc, which are generally included in high-quality palm fertilizers. Fertilizers should be applied at three-month intervals. This would include fertilizing in late fall to provide nutrients over the winter months, when Phoenix palms may be stressed by low temperatures.
  
  

Indoor Phoenix Palm Plants

• The smaller Phoenix palm varieties are often grown as indoor plants in homes, offices and other commercial centers. Phoenix plants, like the pygmy date palm, have attractive, feathery fronds that add a tropical note to indoor environments, yet are easy to maintain with regular waterings, extra humidity when needed and good air circulation. You should fertilize Phoenix palms with a palm tree food that contains trace elements in the spring and summer. In the winter months, you can withhold nitrogen and other fertilizers, according to Botanical Journeys Plant Guides.
  
  

Indoor/Outdoor Phoenix Plants

• Many gardeners who live in colder climates grow their Phoenix palm plants in containers, so that they have them outdoors in the summer months and indoors when temperatures fall. Keeping these plants in good condition requires a change in fertilizing schedule when they are outdoors, where nitrogen and other elements in fertilizer can be lost quickly. Using a fertilizer that has 3-1-3 ratio will provide enough potassium to nitrogen for outdoor plants, according to Jungle Music. You should always work the fertilizer into the soil carefully to prevent burning of the plant. In containers, salts can build up quickly, so you must leach the roots with plain water to remove some of these compounds to keep your Phoenix plant healthy and before bringing palms indoors for the winter. For the winter months, withhold fertilizer to prevent weak winter growth of leaves.