In the Garden:
Southwestern Deserts
March, 2011
Regional Report

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3744

Although winter rain was scant, African daisies germinated in this planting, while natives did not.

Invasive African Daisies

We didn't receive sufficient winter rainfall to produce much of a spring wildflower show in natural areas, although we can still enjoy displays at public gardens or in landscapes. Perhaps you have noticed front yards or street medians with a glowing carpet of orange and yellow African daisies, also called cape marigold. Sadly, these pretty, non-native flowers (Dimorphotheca sinuata or D. aurantiaca) have invasive tendencies in hot, dry desert areas.

The concern is that African daisies will reach natural areas and out-compete the native wildflowers that native creatures rely upon for survival. With so many people living adjacent to mountain preserves, desert parks, and national forests, African daisies don't have far to travel to gain a foothold. Their seeds are light and easily carried by wind.

Unfortunately, non-native species are sometimes planted and promoted before there's a good understanding of how they will perform in local conditions over decades. Some of our worst invasive plant problems were originally thought to be a good idea, such as planting salt cedar to control soil erosion or buffelgrass as livestock forage in the 1930s.

Native Wildflowers
Some gardeners may have started out sowing a vibrant mix of wildflowers in their landscape, which included Sonoran desert native bluebells, poppies, and penstemons, as well as African daisies. Unless the gardener was diligent about thinning, African daisies likely began to crowd out the natives within a few years.

It may be hard to fathom how a few flowers in our yard can become an invasive pest, but with African daisies, it's easy to spot their aggressive tendencies in a neighborhood. When you see a yard full of African daisies, look nearby. You'll likely spy pockets of daisies popping up on adjacent landscapes or medians. African daisies are extremely drought tolerant, and after a number of years, if left unchecked, they spread along an entire streetscape.

Some public gardens no longer offer African daisies for sale during their plant sales. Sunset Western Garden Book cautions against planting them near natural areas. At this point, it's best not to add African daisies to your landscape. Why take the chance that you are contributing to a future calamity when there are excellent native options that give you the same colorful attributes, such as Mexican gold poppy (Eschscholzia californica ssp. mexicana).

And if you have a monoculture of African daisies, maybe it's time to remove them and update your look with a Sonoran wildflower mix. Just be sure to read the content list on seed mix packets before purchase to make sure the mix contains only native species.


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