Many of us have to bring cacti indoors for the winter to protect them from the cold. While this is necessary in many cold winter climates, by doing this we may be creating conditions where cacti will not flower. Too much water, too much heat, and too little bright light provide reasons that answer, “Why isn’t my cactus blooming?”Reasons why a cactus does not bloomIn fact, the type of cacti you grow may not produce flowers for many decades. 50 to 100 years are not uncommon for cactus flowering times for certain varieties. If you want ready-flowering indoor cacti, choose from the following types:How to make a cactus bloomIf you’re keeping cacti indoors during the winter, try to place them in the coolest spot. While they probably won’t survive below 20 degrees Fahrenheit (-6 C) outdoors, they do need a chilling period to bloom. Also remember that they need to stay completely dry when out in this cold weather. Indoor cacti do not need water even in winter. During their dormant period, hold back all water and wait for signs of growth to resume watering. This encourages flowering. If you haven’t positioned your cacti in full sun at this point, this is a great way to get blooms. Full morning sun is best, with the exception of jungle/woodland cacti which will tolerate dappled sun or just bright light. Like other plants, cacti should be gradually acclimated to the sun so that they do not get sunburned. Start with an hour or two and increase the number weekly for desert cacti until your plant gets at least six hours of sun daily. An indoor lighting system can work when actual sunshine is not available. However, if you can put the plant outside in warm temperatures, do so. When you start watering again, you can also lightly fertilize with a high-phosphorus fertilizer. Use at half strength and water first. If you already have fertilizer on hand, check the fertilizer ratio and make sure the middle number is the highest. Nitrogen fertilizer (first number) is not good for cacti and succulents as it produces weak and spindly growth, so avoid this if possible. Fertilizers high in phosphorus are sometimes referred to as “bloom busters.”
