Letting the Garden Garden: Native Self-Seeding Annuals

One of my favorite flowers in the garden is a plant that some might mistake for a weed: Annual fleabane.  Now, a fleabane doesn’t sound like much, but I love this plant, and each year I am excited to see where it will grow – a spot in a garden bed?  The lawn? A planter? Anywhere?  It is all ok with me. 

Annual Fleabane is a graceful, 3 to 4 foot tall plant that blooms from early June through much of the summer, with little white daisy-like flowers. They are bright and cheerful during the day and seem to glow at dusk.  And on an evening (even if I am just taking out the compost), when I pass through the annual fleabane, with the fireflies flashing, I feel like I’ve wandered into a magical place -all the more magical because I did not plant this plant!  I’ve never planted it.  Years ago, annual fleabane just arrived in my garden and planted its own plant-self.  

Depend on Disturbance

Annual fleabane is in a class of plants that has recently been getting a little more attention: Self-seeding Annuals.  Short-lived plants that will grow and bloom pretty quickly, set seeds, and then… die.  But their seeds carry on!  And once in the garden, the cycle of blooming and seeding should continue, as long as your garden has a little open spot for them.  

Many plants that fit into this live fast, die young life plan are considered to be disturbance dependent. In nature, they are depending on bare ground creating events: a flood, or fire, a tree falling over, or a new buffalo wallow, something that opens up a patch (or thousands of acres in some cases) of soil and creates a space that is mostly free of competition for light, water, and nutrients.  Disturbance dependent plants need to grow fast and spread many seeds before bigger rooted, bigger bodied, longer lived plants take residence and out compete them.  

In my garden, a disturbance mostly means our dog digging for moles, or me smothering a spot with a forgotten tray of plants, or the kids playing with the jet setting on the hose.  As galling as some of these disturbances can be, annual fleabane and other self-seeding annuals need these dynamic, ephemeral patches of bare earth in the garden where their seeds can continue making a go of it.

Native Gardens: Playin’ Chess, not Checkers!

“A traditional gardener’s definition of success is when a plant survives, but an ecologist doesn’t view that plant as successful unless it also reproduces.”

Larry Weaner and Thomas Christopher, Garden Revolution, How our landscapes can be a source of environmental change

In the excellent and useful book, Garden Revolution, How our landscapes can be a source of environmental change, Larry Weaner and Thomas Christopher write so well about how to ecologically design meadows (or prairies) so they are successful and self-sustaining in the long term. And most of the ecological lessons for larger plantings are just as useful in a smaller home garden. One point they raise is the importance of including plants with multiple reproductive strategies. Seed droppers, wind dispersers, animal dispersers, rhizomes, stolons, you name it, these guys are arguing for biodiversity. And although they have noble reasons for doing so, like supporting more complex ecosystems, they also have an eye to practicality: filling the many ecological niches (a.k.a. the many ways plants grow and function) in a garden, means there is less opportunity for weeds to fill those niches, and that a garden can become less maintenance over time.

For example, let’s say the ground got a bit messed up when you were transplanting purple coneflowers. Well, if you have enough fast growing, self-seeding annuals dropping seeds in your soil seed bank, that spot is more likely to be filled by black-eyed susan, or annual fleabane rather than some lousy garlic mustard (or some other exotic invasive) -that is the general idea.

Now, if you do not have children or dogs who will blissfully destroy your garden for you, you can be intentional when creating bare earth in the garden. In Garden Revolution, they discuss this: placing seeds heads of cardinal flower on bare ground right where they’d like to see them in a couple years; gathering seeds, scratching up the dirt and helping easy spreaders spread, right where they want them. Last fall I gave it a go because I’d like more annual fleabane in the lawn. I know it sounds a little crazy, but for me, leaving patches of annual fleabane to grow up and walk through, or pass by, here and there in the lawn, creates such an ethereal atmosphere and an expanded sense of being in the garden. The garden -not just for garden beds anymore.

The Case for Self-Seeding Annuals, Continued

Some of these self-seeding annuals are plants that are already common in the garden, like black-eyed Susans (Rudbeckia hirta), or some often arrive of their own accord, like tall bellflower (Campanula americana). But I guess I feel like a bigger case needs to be made for this class of plants because while looking things up for this post (and my own garden), it became apparent that, while many are easy to find, some of these plants are just not available. For example, I would really love to get large flowered clammyweed (Polanisia dodecandra subspecies trachysperma) -very difficult to find the seeds! And I’m sorry, I know I’ve been talking about annual fleabane, but you can not buy the seeds anywhere! I’m sorry! What gives! (Fortunately, if you keep an eye out, you might be able to just find annual fleabane in your yard.)

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So here is my extra case for self-seeding annuals, beyond biodiversity and weed suppression (which are truly good reasons in themselves).

1. Self-seeding annuals are fun. I’m not just saying this because I am enthusiastic about these things. It is true.
2. These plants pop up in surprising places and keep the garden design lively and changing.
3. Unexpected plant combinations can be inspiring.

4. Many bloom their first year and have a long bloom time!
5. This is especially good for the first year or two in a planting, adding flowers before longer-lived perennials come into their own.
6. They plant themselves!  (I really, really appreciate this.)
7. Many are host plants for a variety of moths and butterflies, and
8. Some support pollen specialist bees.
9. A lot of these guys are pretty short, which can be useful in the garden.
10. Surprise reasons that I don’t know right now that are even better than the reasons above.

With all that said, after some searching and cross-referencing, here is a list of native self-seeding annuals and biennials that I am excited to include in my Mid-west garden (and many are native to other regions as well).

Native Self-seeding Annuals! (and some biennials!)

Many thanks to Dr. John Hilty of Illinois Wildflowers for the use of the following photos and for maintaining his great online wildflower resource (each flower name links to Illinois Wildflower’s botanical information when possible).

And if there are any plants you think I have missed here, please let me know!!

A printable list can be found here:

Quick Garden Tips

Just a couple tips when trying to encourage these guys in the garden:

1. Try to reduce mulch in the garden, or reduce mulching in early spring. Mulch that suppresses the germination of weed seeds will also suppress the germination of self-seeding natives. Mulching later allows for seedlings to grow a bit and then you can mulch around them.
2. If an area is quite thick with self-seeded seedlings, go ahead and thin them out to a good plant spacing, so the ones left can grow well.

I’m very curious to know what your favorite self-seeding annuals might be. Please let me know in the comments!

Resources:

Garden Revolution: How Our Landscapes Can Be a Source of Environmental Change, by Larry Weaner and Thomas Christopher

Illinois Wildflowers, by Dr. John Hilty

Native Plants of the Midwest: A Comprehensive Guide to the Best 500 Species for the Garden, by Alan Branhagen

Prairie Moon Nursery

Growing Home with Native Self-Sowers, by Jared Barnes

Tips for Using Self-seeding Plants in the Garden, by Megan Shinn

Ladybird Johnson Wildflower Center

Plantiful: Start Small, Grow Big with 150 Plants That Spread, Self-Sow, and Overwinter, by Kristin Green

Cultivating Chaos: How to Enrich Landscapes with Self-Seeding Plants, by Jonas Reif, Christian Kress, Jurgen Becker