To: Master Gardeners
Subject: Arithmeum Plant
I bought a Mauve/Purple Arithmeum Plant near the end of the winter – it bloomed for a very long time. New leaves appear regularly. It seems to like the spot it is in as there is a large window not far from the table on which it stands.
How do I get it to bloom again?
Your help is much appreciated.
Plants have many common names. I think your Purple Arithmeum plant is what I think of as one of the Anthurium species, Anthurium being the botanical name for the plant. If you can provide the right conditions for the plant, Anthurium will bloom year round usually at about three month intervals. Anthurium needs bright, indirect light. The location of your plant in your photo looks ideal but be aware that a north facing window may not provide a sufficiently bright light. Anthurium requires a coarse, well draining potting mix. The soil should be kept moist and not allowed to completely dry out. The plant prefers high humidity which can be a problem in many of our homes during the winter months. The use of a humidifier can help if humidity is an issue at your house.
Anthuriums will benefit from the addition of fertilizer when they are actively growing. Applying a liquid fertilizer at ¼ strength weekly during the growth period is recommended. Anthuriums are tropical plants and in their native environment (Central and South America and the Caribbean) they grow year round. We can try our best to mimic these tropical conditions in our homes but the lower light and humidity we experience during the fall and winter months will reduce growth. During these periods, it is recommended to stop fertilization until growth resumes in the spring. When selecting a fertilizer, choose one that is high in phosphorous which promotes flower production. You can tell if a fertilizer is high in phosphorous by checking the NPK ratio on the package. The NPK ratio identifies the ratio in the fertilizer of the three main macronutrients required by plants: nitrogen, phosphorous and potassium. The ratio will look something like 15-30-15. Look for a higher middle number. A fertilizer intended for orchids can be a good choice.
If you’d like to read more about Anthuriums, I’m including a link below to a good article on their care. I notice that the article recommends setting your plant on a tray of pebbles to raise humidity. Tests have found that this method raises the humidity such s small amount as to have no effect on plants. Misting is also of limited value. As the water droplets from the misting dries, the vapor spreads out into the room. So the humidity around the plant will only be higher while there is water sitting on the plant. To effect your plants, you need to raise the humidity in the whole room.
I hope this information helps and you’ll soon see some new blooms on your Anthurium.