Green Thumb Tip #22: Do the Math

Two Athyrium ‘Branford Rambler’ that I picked up on an August clearance sale on Saturday are ready for division.


Every garden center offers deals in August to move out the last of their summer stock so there is room for all of those fall pansies and chrysanthemums already on their way.  You will find a very good selection of all of the major genera at most good nurseries, but now marked down 20-40%.

They may be pot bound and perhaps a little sun scorched; no worries.  With a little effort and skill you can increase that small investment many fold.  With a perennial, it is always the roots, crowns, rhizomes, tubers, or stolons that matter.  These are the parts that survive and increase year to year.  The flowers and foliage come and go with the seasons.

This late in the season, the bargain perennial you score on discount has likely had many weeks to grow and increase in its nursery pot.  That means that you can divide it into several pieces, re-pot them and grow them on so that you end up with several beautiful plants before fall really takes hold.  We still have a good eight weeks of summer growing weather, here in coastal Virginia, before we even think about a first frost.


These will grow into dense ferns, as this Japanese painted fern hybrid spreads itself around.  I like the red stems.  Because this is a deciduous hardy fern, it will fade away over the winter.  But come spring, it will reemerge with red fiddle heads.


I found two Athyrium ‘Branford Rambler’ ferns this weekend on clearance at 20% off their original price.  This is a  lady fern hybrid produced from a cross with a Japanese Painted fern.  The central stem of each frond is deep red, and I expect the fiddle heads next spring to be deep red, too.  These ferns like moist acidic soil and full to partial shade.  This fern is known for spreading rapidly, and will grow to about 24″ high and wide.

I bought these ferns because I’m planning to design some winter perennial and bulb pots in October, and think that fern fronds emerging through the daffodils will look terrific!  I want some small divisions of a Japanese painted fern hybrid to plant among the bulbs, for their red fiddleheads, and I’ll finish the pots with Violas or Heuchera divisions.

When deciding which perennials to buy this time of year, compare all of the available pots of whatever plant you are considering.  Look for ones that have multiple crowns or divisions which can be pulled apart.



You will need several clean, empty pots that are deep enough to accommodate roots of your divisions, some fresh potting soil, a clean knife or hori-hori and space to work comfortably.  I also have something to line the pots to hold the soil, like a coffee filter or paper toweling.  Your new plants will only live in these pots for a few weeks, so this is a temporary pot and can be a little rough.

I begin by guessing how many divisions are possible from the plant, and then prepare a pot for each by lining it with paper and filling it about 1/4 full of fresh potting soil.  Next, I massage the nursery pot with the mother plant to loosen up the roots, and then gently slide the root ball out of the pot.  Always work with a well-moistened root ball.  If the plant comes home dry, water it well first thing, and give it a few hours before beginning any division.



As soon as you study the roots and plant structure you will likely see where you can divide the plant so that each new division has both leaves and roots.   If the plant has rhizomes, tubers or stolons, make sure that each division has a section attached to both leaves and roots.



Some plants, like my ferns, can be gently pulled and teased apart by hand.  Other plants may need to be cut into divisions.  Make sure that your blade is clean before you begin work on each plant by wiping it with a Lysol or other disinfectant wipe, washing it in hot soapy water, or even spraying it with a spray disinfectant.  This will control the spread of any bacteria or fungi  that may be on your tools.


Notice where there are spaces between sections where you can begin to pull the plant apart.


I like to work as quickly as I can so the roots don’t dry out, and usually pot up each division as I cut it free.  Position the roots in the new nursery pot so that the plant’s crown will be about an inch below the rim of the pot, and gently fill around the root ball with fresh potting soil.  Firm the soil as you go so that the division will stand up and not flop over and the soil is firm around the roots.



Water each newly planted division after you pot it, keeping in mind that your fresh potting soil may not be holding much water.  It is good to do this on a rainy day and let the divisions sit out in a gentle rain.  Always take care to keep newly divided perennials in a shady place for at least a day as they recover and settle in their roots.

I wouldn’t put even full sun perennials back into full sun for at least a week, to give them a chance to adjust.  Since I’m working with ferns, I’ll put them in full shade for the first week or so, and then move them to brighter, partial shade.  It is very important to keep the soil moist, but not wet, as plants begin to grow their new root systems.

I like to water newly divided plants with Neptune’s Harvest seaweed and fish emulsion right after they are divided, and then every couple of weeks as they grow on.  You might also sprinkle the soil with Osmocote time release fertilizer to help the plants recover and begin growing again.

The plan is to stimulate growth over these last few weeks of summer, and then plant the divisions into garden beds or pots several weeks before the first frost.  You want to allow a few weeks for any newly planted perennial to grow roots beyond the planting hole, out into the surrounding soil, before the ground freezes.  This helps reduce heaving when the ground freezes hard, because the plant is anchored by its roots.



I bought two plants, and ended up with nine divisions.   This is why I always save plastic nursery flats and nursery pots that come home with me on my plant hunting trips.  There are so many ways to reuse these very useful tools!  All nine of my new divisions are nestled into sturdy flats, where they will be easy to move and manage as I grow them on through September.

Unless you have unlimited funds for gardening, do the math.  Shop the seasonal bargains, and then use those bargain plants to make many more.  Whether you divide them, take cuttings to root from leggy plants, or gather their seeds- many plants on sale now offer abundant material that a thoughtful gardener can use to increase her collection and fill her garden with more texture and color.

Plant more plants!



Woodland Gnome 2018

“Green Thumb” Tips: 

Many visitors to Forest Garden are amazing gardeners with years of experience to share.  Others are just getting started, and are looking for a few ‘tips and tricks’ to help grow the garden of their dreams.

I believe the only difference between a “Green Thumb” and a “Brown Thumb” is a little bit of know-how and a lot of passion for our plants.

If you feel inclined to share a little bit of what you know from your years of gardening experience, please create a new post titled: “Green Thumb” Tip: (topic) and include a link back to this page.  I’ll update this page with a clear link back to your post in a listing by topic, so others can find your post, and will include the link in all future “Green Thumb” Tip posts.

Let’s work together to build an online resource of helpful tips for all of those who are passionate about gardens and gardening.
Green Thumb Tip #16: Diversify!
Green Thumb Tip #17: Give Them Time
Green Thumb Tip # 18: Edit!
Green Thumb Tip #19:  Focus on Foliage
Green Thumb Tip #20:  Go With the Flow
Green Thumb Tip #21:  The Mid-Summer Snack


About woodlandgnome

Lifelong teacher and gardener.

2 responses to “Green Thumb Tip #22: Do the Math

  1. Oh, how naughty. I do the same with alstroemerias and cannas that I get in the morgue section of the nursery when they die back for a season.

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