I have a love/hate relationship with annuals. Linda Gay, the director of Mercer Arboretum here in Houston calls them nitrogen junkies, because of their dependence on fertilizer — and lots of it — for that signature ‘pop’ of color that they bring to our landscapes.
Here in Houston, we see lots of salvias, the periwinkle blue of Russian salvia, the deep red of Salvia Greggii, even some lovely white varieties, which I particularly like because they make me feel cooler, even when the temps are in the high 90s. (Six months out of our year.) While petunias used to be impossible for us due to the heat, there have been several heat-resistant varieties introduced in recent years that work quite well. Then there are the grasses. Lovely for their contribution of texture and motion to the landscape, I use several in a variety of locations. Grass at least is not as dependent on nitrogen for its allure as the other, more colorful annuals.
So how do we enable these plants in their addiction? The following advice from a Better Homes and Garden’s article shows you the standard advice.
For flowering annuals, use an all-purpose plant food, such as a 5-10-5 or 10-10-10 formula. Flowering plants have a special need of phosphorous and potassium to realize their blooming potential. Foliage plants will flourish with a formula higher in nitrogen (the first of the three numbers in a fertilizer formula).
But do we need to heed this advice? Well, short answer is yes. If you want blooms on your plants, you must provide the food they need to produce the flowers. There are, however, additional ways to provide the nutrition they crave without dumping 5-10-5 on them every two weeks:
- Build your soil — use compost to amend your soil so that it holds on to its nutrients better.
- Water every other week with compost tea.
- Consider using more perennials to build your landscape — still holding to the two above tenants to get them to give you the colorful blooms you want.