Starve Nasturtiums Into Blooming

Nasturtiums bloom best in poor soil. Photo:

Question: I bought nasturtiums for my two flower boxes. For three weeks, the boxes have been filled with very large leaves, but only one flower per box. I added compost and flower fertilizer, but it doesn’t seem to help. What should I do?

Richard V.

Answer: The nasturtium (Tropaeolum majus), unlike almost any other annual flower, simply doesn’t like rich soils. A soil too rich in minerals, especially nitrogen, the first number of the three that we see on ferilizer labels, tends to produce an abundance of beautiful and very lush leaves, but very few flowers. Other factors to consider would be too little light (it prefers full sun) and overly sparse watering, but usually the combination of beautiful leaves and few to no blooms flowers simply means the plant is being overfed.

So, for this year, simply stop fertilizing. The concentration of minerals will eventually decrease and more abundant flowering should begin. As for next year, sow or transplant your nasturtiums into ordinary container soil mix, without adding compost or fertilizer, and you should see the plants in full bloom right from the beginning of the season.

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

2 comments on “Starve Nasturtiums Into Blooming

  1. That happens with several types of plants, and is very obvious with bougainvillea.

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