Home of the Practically Perfect Pink Phlox and other native plants for pollinators

Tuesday, April 5, 2016

The thing about biennials

Biennials require two growing seasons to complete their life-cycle. The first year is vegetative growth; the second year, they flower and produce seed and shortly after, they die. They're usually quite prolific and will set seed well, but, you'll only have flowers every other year. If you want to have blooms every year, you've got to put a little bit of effort into making that happen.
My favorite native biennial is Phacelia bipinnatifida.
Purple phacelia/Phacelia bipinnatifida is one of my favorite spring flowers and it happens to be a biennial. I fell in love with it about 20 years ago and have worked to make sure it thrives in my garden. It's a pretty ground cover when it colonizes and it has good wildlife value (provides nectar and pollen for the earliest pollinators).
You can have a yearly blooming colony.
It's an excellent pollen and nectar source for early pollinating visitors. 

The easiest way is to find a source of first year seedlings and/or second year plants of the biennial of your choice. That's not always possible with underused natives like Phacelia bipinnatifida. Sometimes native plant nurseries sell annuals and biennials, but, most of the time you'll have to start with seeds. (Locals, you can call GroWild to see if they still have plants available otherwise, check the internet for seeds). 

If you only have one flowering plant you can still have blooms every year, it will just take a few years. It will take a little bit longer if you start with seeds.

The process:

First Spring with your biennial.  If you have a second year plant, it will bloom! Collect mature seeds (on my Phacelia it's when the ovoid capsules are ready to split), save some (Cleaned seeds should be stored dry in sealed, refrigerated containers) and direct sow others. Biennials reproduce through seeds.

If you're starting with seeds, sow them now! The seeds will germinate early the next spring, here in Middle Tennessee that often means in late February.

first leaves and true leaves

Second Spring: Seedlings will be everywhere you sowed them (cotyledons of Phacelia bipinnatifida are oval) and will rosette up (pinnately divided leaves) as the growing season continues! You can transplant them anytime, but I like to wait until fall when the rains and cool weather return.  

Now is the time to sow those seeds you saved last spring! Direct sow them into the garden and gently press the seeds into the soil. I promise you they will germinate if you've chosen the right spot in your garden. Phacelia likes moister conditions, so I plant them where I know they'll thrive.
 first year seedlings with pinnately divided leaves November 2015

Third Spring: You should now have first and second year plants and be on your way to having a wonderful yearly show! Continue to collect seeds for sowing wherever in your garden that your biennial will be happy or let them drop onto the soil where they've been growing. Continue transplanting first year rosettes during the fall.
This is what you can expect every Spring. Aren't they lovely!

They take a little bit of effort, but the results are very satisfying! 

Gail Eichelberger is a gardener and therapist in Middle Tennessee. She loves wildflowers and native plants and thoroughly enjoys writing about the ones she grows at Clay and Limestone. She reminds all that the words and images are the property of the author and cannot be used without written permission.


  1. These little strumpets are all over one end of my garden. They are so pretty when all in bloom.

  2. I have so many small seedling in my shade garden I can't walk without stepping on these babies.������

  3. A pretty little flower -- looks great massed in your garden! Not sure that grows around here (STL)...

    1. Alan, Hello. It's native to MO so it might very well be happy in your garden.

  4. A lovely little biennial, and a nice, simple strategy for yearly blooms! This phacelia isn't native to my area, but there are a few native species here, too.

  5. I don't have any. Save me some seeds! I will trade you....what would you like?

  6. I wish I could grow this but my climate is too harsh. It's a lovely little plant.

  7. They are lovely, so delicate and such a soft shade of lavender. Thank you for the fabulous tip! Now all I need is some bare dirt! : )

  8. A great description of how biennials work. And what a lovely plant, in so many ways.

  9. I'm really tempted to find some seed - when I first looked at the flowers thought I was looking at Polemonium, or perhaps a Geranium - but no - a new plant I've never seen! Thank you. With some of the natives find that after several years that some of my biennials like the Ipomopsis start germinating willy nilly, so I end up with colour every year. Oh the perils of blog-visits...Gail, I'm seeing early rivers of purple in my garden and I haven't even identified a seed source.....B.

  10. I love your description Gail...and a perfect biennial to start with!

  11. Very pretty flowers! I rarely grow biennials because of the effort, but I should, since I often grow perennials from seed that take a couple years to develop flowers and biennials wouldn't take that much more effort.

  12. A lovely plant. I looked it up and was surprised to learn that it is native to Illinois, though it can be found mainly in the southern half of the state.

  13. I have a different phacelia grown from seeds sent to me from a blogger in British Columbia. But it's thriving near my rain garden and the pollinators love it. :o)

  14. I like it how you explained it, so that anyone who is totally new to gardening would completely understand what biennials and how to look after them. Very easy and good read, I approve.

    Regards, Irvine

  15. You are right, the Purple Phacelia is an interesting and beautiful plant. My favorite flower is the Orchid and I planted it at home 2 years ago. Very hard to grow but has marvelous bloom.


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