Learn Why Your Flowering Plants Aren't Blooming

Using Too Much Fertilizer

It's true that feeding your plants with a high-nitrogen fertilizer will promote lots of green, leafy growth, but all this growth is usually at the expense of flowers. It's also true that plants need phosphorous to set flower buds. But before fertilizing, you need to look at the whole picture.

If your plants look otherwise healthy, check for other problems first. If they show signs of malaise or stress, check all the growing conditions. Is the plant getting plenty of sun and water? Are there any signs of disease or pests? How do the other nearby plants look? Have you had your soil tested recently? If your soil pH isn't in a good range, it won't matter how much fertilizer you add; your plants won't be able to access it. All these factors work in combination.

Pruning at the Wrong Time

Historically, late-season pruning was a very common cause of a lack of flowers for shrubs and trees. Pruning plants late in the season can remove all the buds for next year's flowers. Lilacs, forsythia, and some hydrangeas can set their buds a year in advance. However, this is becoming less of an issue as new plants are developed that can bloom on new growth. In particular, new hydrangeas that bloom all season, even if you cut them while they're growing, are being introduced every year. But if you have older shrubs and trees that you want to keep, you'll need to know when it's time to hold off on pruning.

Waiting for Maturity

Most plants are not ready to bloom until they put down roots and have a season or more to mature. Remember, plants don't flower out of vanity. Flowering is how they propagate their species, and it takes a lot of energy. Some plants, like biennials, die shortly after flowering. That's why deadheading before a plant has a chance to set seed can force it to bloom again.

It helps to know something about the type of flower you are growing:

• Annuals should flower their first year, but it can still take several months for them to mature. You may not see flowers until mid to late summer.
• Biennials, like hollyhocks, do not usually bloom at all their first year and then fade away shortly after flowering in their second season.
• Perennials are being bred to flower more quickly. If you are buying large plants, they should be plenty old enough to start blooming the first year you plant them. Even flowering trees and shrubs are being designed with the impatient gardener in mind. But there are still plenty of old-fashioned varieties out there that need to settle in before they hit their stride. Once they do, they should become reliable bloomers.

Exposing to Sunlight and Warmth

Many flowers require at least six hours of sun to set buds. Plants need the sun to photosynthesize; this is how they take the raw materials of carbon dioxide and water and turn them into the sugars they need to feed themselves. If they don't get enough sun, they become stressed. One of the first things a stressed plant does is drop its flowers and buds and put all its resources into staying alive. Growth, in general, will become sparse; the plant will grow tall and gangly and start reaching in the direction of the sun.

Temperature also plays a role in flowering. The warmth of the sun is often what is needed for a flower to open, so the time of day the sun shines on your flower garden also plays a role. Morning light is cooler. Plants with an eastern exposure may be getting only morning sun. Flowers that require "full sun" will bloom more in a western exposure, where they get the hotter afternoon rays. Of course, there are plants that will wilt or fry in the hot afternoon sun, so learn what your plant likes.

Controlling Winter Damage

Weather can have a huge impact on the health of your plants. Snow is not usually the problem since it acts as an insulator and protects plants. But cold winters with no snow cover and harsh, frigid winds can easily damage or kill flower buds. Dry winters can cause plants to forego flowering because they go into preservation mode, while wet springs can bring on early fungal diseases and rot.

Flowers that need a period of cold to set their flowers buds or to break dormancy, such as spring bulbs and peonies, won't get what they need if the winter is too warm. This can also cause some plants to come out of dormancy early, only to be killed back by a late spring frost or snowstorm.

Too cold, not cold enough, too wet, or too dry? There's really not much we can do about this other than looking for varieties that are well-suited to our area. Even then, there will be seasons when we will just have to roll with the punches.