Set your roots free on this Independence Day week!

We’ve discussed barerooting/rootwashing trees before, and research on this controversial topic continues. But what about smaller shrubs and woody perennials? What about herbaceous perennials? Basically, what about PERENNIALS???

Lobelia laxiflora

I’ve always made a practice of rootwashing everything except for annuals. They don’t last long enough to suffer the perils of potbound plants. But many gardeners are nervous about disrupting more fragile root systems. Let’s see what happens when we do.

Lavandula ‘Winter Bee’

A little context: we’ve just moved to our family farm, which has AMAZING spring flowers that the bees love. But once those are gone…there’s nothing. I was desperate to provide some food for bees and butterflies, so it was off to the nursery to shell out a few hundred bucks for the beginnings of our south-facing pollinator garden – a previously barren spot left after construction of our porch.

Lavandula ‘Bandera Purple’

So I bought Lavandula stoechas ‘Bandera Purple’ and ‘Winter Bee’, Salvia ‘Caradonna’, Agastache ‘Acapulco Deluxe Red’ and ‘Blue Boa’, Erysimum ‘Winter Passion’, Verbena ‘Homestead Purple’, and Lobelia laxiflora. I depotted and soaked them in a water bath, using a gentle hose setting to loosen up media in the center. For most of these plants, a massive root disk at the bottom of the pot had to be cut off like a giant slice of salami. If necessary, I “tickled” the remaining rootball to work out the rest of the media.

Here is Erysimum ‘Winter Passion’ potted, depotted, and washed.

Not too bad…

The Agastache and Verbena cultivars were also in pretty good shape, much like the Erysimum. Just a gentle washing and tickling was enough to remove all the media and reveal the roots.

Here is Salvia ‘Caradonna’ potted, depotted, and washed, and Lobelia laxiflora potted, depotted, and washed.

Apart from the root Frisbee on the bottom of each pot, the roots were confined to the center of the pot, pretty much where they had been in their previous container.  So question number one for all of you gardeners – why would you want to dig a hole to plant all of that media (which is nothing like your soil)? My answer – you don’t! Keep that good organic material as part of your topdressing.

Here is Lavandula stoechas ‘Bandera Purple’ potted, depotted, and washed;

and here is Lavandula stoechas ‘Winter Bee’ potted, depotted, and washed.

I have to take time out for a special rant about the lavenders (retailing at $19.99 and $12.99). Look at the root mass of the ‘Winter Bee’. It’s entirely unacceptable. The woody roots are in the shape of the liner pot from transplants past. News alert: these systems do NOT self-correct. They must be straightened or pruned to regain a natural structure. The ‘Bandera Purple’ – the more expensive of the two – was actually three plants in one color-coordinated bowl (“Go ‘Colour Crazy’ with matching pots and flowers”!). Fine by me – I just got 2 free plants. (By the way, this is nothing new for me – I’ve written about it previously here and here.)

Another upside is that hole digging was short and sweet. Holes were just deep enough to accommodate the root mass and wide enough to allow roots to be spread. Soil was added and watered in. The leftover organic media was used as the first layer of topdressing, followed by a fresh woodchip mulch. And then irrigation to soak the mulch well.

Salvia ‘Caradonna’

It’s important when you rootwash plants to provide optimal soil water every day, particularly when it’s hot and sunny (as this south-facing garden is). Even with the gentlest root washing there will be a loss of fine roots. But the continuity of the soil system means that the soil around the roots will be just as moist as the rest of the bed. Roots left in soilless media quickly dry out. Yes, I had afternoon wilt on many of the taller plants during the first week or so, but they recovered every evening. The wilt has become less noticeable since then.

Agastache ‘Acapulco Deluxe Red’

So here’s how they look 3 weeks after planting (sunny day, about 80°F). And I’m happy to report that not only birds and butterflies but hummingbirds have been visiting our pollinator oasis garden. And all those single photos scattered through the post? They are all close-ups from this garden – taken just minutes ago.

South-facing pollinator garden

(Question number two for gardeners – what are you waiting for?)

 

 

Published by

Linda Chalker-Scott

Dr. Linda Chalker-Scott has a Ph.D. in Horticulture from Oregon State University and is an ISA certified arborist and an ASCA consulting arborist. She is WSU’s Extension Urban Horticulturist and an Associate Professor in the Department of Horticulture, and holds two affiliate associate professor positions at University of Washington. She conducts research in applied plant and soil sciences, publishing the results in scientific articles and university Extension fact sheets. Linda also is the award-winning author of five books: the horticultural myth-busting The Informed Gardener (2008) and The Informed Gardener Blooms Again (2010) from the University of Washington Press and Sustainable Landscapes and Gardens: Good Science – Practical Application (2009) from GFG Publishing, Inc., and How Plants Work: The Science Behind the Amazing Things Plants Do from Timber Press (2015). Her latest effort is an update of Art Kruckeberg’s Gardening with Native Plants of the Pacific Northwest from UW Press (2019). In 2018 Linda was featured in a video series – The Science of Gardening – produced by The Great Courses. She also is one of the Garden Professors – a group of academic colleagues who educate and entertain through their blog and Facebook pages. Linda’s contribution to gardeners was recognized in 2017 by the Association for Garden Communicators as the first recipient of their Cynthia Westcott Scientific Writing Award. "The Garden Professors" Facebook page - www.facebook.com/TheGardenProfessors "The Garden Professors" Facebook group - www.facebook.com/groups/GardenProfessors Books: http://www.sustainablelandscapesandgardens.com

13 thoughts on “Set your roots free on this Independence Day week!”

  1. Does lavender survive the Northwest winter? I’m in a Zone 6 Northeast region and have not been successful yet. This year I am trying Phenomenal, which was recommended as more winter hardy.

  2. I am almost convinced in the case of correcting the harm done by the garden centre’s potting but do not feel tempted to wash roots when just dividing plants in the garden

    My aged eyes would pick up more detail if your pictures were bigger. I realise clicking on them will help
    PS Lobelia laxiflora is pretty rare over here in England but I am pleased to report it does well for me in York

    1. Unfortunately I’m technologically limited when it comes to adjusting the code to make the photos larger in the post – this is the default size. You can, as you note, click on them to see them better.

  3. This article doesn’t address what are the advantages of doing this method. I love to see pictures of the root ball system 2, 4, and 6 weeks between using this rootwashing method and the regular loosening method.

  4. I received a gorgeous lavender from my son for Mother’s Day, that looked similar to the one in your picture. It was large and full of beautiful blooms. Within 3 days it began wilting rapidly. I had already removed the decorative foil, so I slid it out of the pot – horribly rootbound. I clipped around the bottom edge (the “frisbee”), and teased roots from the sides and bottom. The medium that was left – small bark chips and gravel – fell away. I transplanted it into a slightly bigger pot of potting soil, spreading what roots I had loosened, and gingerly watered it. I also clipped most of the blooms off. Within 2 more days, half of the lavender was dead. As it wasn’t near as full, so closer inspection showed that there had been two large lavenders planted in that original 6″ pot. I took it from the pot, removed the dead plant and repotted the remaining wilted lavender again. I left it in a protected area where it received only morning sun. The first few days were encouraging, but within the next 10 days, it too was completely dead.

    If I had known about root washing when I received my gift, I certainly would have tried that method first. It hurt loosing a Mother’s Day gift from my son, especially since I call myself a gardener.

    I did try the method with a Holly purchased a month ago. It was horribly root bound, and I am pleased to report that it is alive and is putting on new growth. I would say the difference between root washing and not root washing would be a living plant vs a dead plant.

  5. I’m going to try your method on Shasta daisies (1 gal. newly purchased at my big box store.) I’ve slashed and teased the heck out of them after I pried them from the container, they still die no matter how much I water after I repot them. ( same thing happens with the ones I try to keep saleable at my big box.) They come in extremely potbound with no room for water.
    I’ll take pictures and post them if possible. love the website!

  6. awesome, thank you. By the way, i recently purchased your course “The Science of Gardening” from The Great Courses. My husband and I are loving it – learning a lot.

  7. Thank you for a well explained method of transplanting plants. It took me too long to understand that most plants are root bound when you buy them and will die if you leave them in the pot.

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