Dividing Perennials

by Andrea Laine EMGV

There’s a saying among gardeners: Sleep, creep, leap.

The first year that an ornamental plant is in the ground, it sleeps. Above ground it looks like nothing is happening. All the action is underground where it is creating strong roots. A quality root system is essential for absorbing water and nutrients to deliver to the rest of the plant.

The following year, the plant creeps. We may notice new leaf buds, an elongated stem, and we are content (or relieved) that the plant is still living.

Then, finally, in its third or fourth year, the plant really starts to get showy. It leaps! There are new leaves and bold flowers. The plant is noticeably taller and/or wider and we gardeners are filled with pride and joy and our enthusiasm for gardening probably leaps, too.  

Stokesia ‘Blue Danube.’ Photo by A. Laine.

This is so true of herbaceous perennials! Before you know it, it is time to divide the perennial into smaller plants. Division can control a plant’s size and invigorate the original plant, assuring that it continues to flower abundantly. (If your perennial no longer flowers very well, that is a sure sign that it is crowded and needs to be divided.) Another benefit is that you will have new plants to place in another part of the garden or share with a friend or neighbor.

Time of year
The best time to divide herbaceous perennials is early spring, however bearded iris and Asiatic lilies prefer later summer to early fall and some plants like black-eyed Susan are so resilient they’ll accept division in spring or fall. Choose a cool or cloudy spring day or an early fall day. Dividing or planting most perennials during a hot and/or humid day, such as we tend to have during a Durham summer, is generally not advised. Also, do not divide or dig around plants the same day they have been watered.

Step-by-step guide

Step 1.  Prepare by putting in place everything you may need to complete the task: a long-handled spade or digging pitchfork, a sharp knife (I use an old steak knife from the kitchen), a full watering can or hose, and newly dug holes in the ground. If you intend to gift your divisions to other gardeners, then also have containers, a small (spade) and potting soil by your side.

Step 2.  Survey your plant(s). From afar, it looked like I had two giant clumps of Stokes Aster (Stokesia ‘Peachies Pink’). See photos below. They had  been in the ground four years. But upon closer inspection, notice that there are actually multiple small clumps growing close together.

Step 3. Dig and separate the plant. Use the spade or fork to dig deep on all four sides of the plant. In the case of these asters, I need not dig up the whole planting, just the smaller clumps that I wish to relocate. If the plant’s divisions are growing closely together, as may be the case with a Daylily or a Bearded Iris, you may need to dig up more, or all, of the plant. When that is the case, gently pull the division away from the original plant. Tease it with your fingers. If this is difficult, as it may be with plants that are overdue for dividing, it’s okay to cut through the clump using the knife. Just be sure that each smaller clump gets three to five shoots and part of the root system.  

Digging to divide a perennial into multiple plants. photo by A. Laine

Step 4. Replant the divisions, with proper spacing and depth (the crown at soil level), as soon as possible into your previously dug holes or at-the-ready containers. The goal is to minimize the amount of time that the roots are exposed to the drying effects of air. Water the new planting well.

As you can see in the photos above, the new divisions look a bit forlorn. They will need nurturing equivalent to any new planting; that means vigilant watering through their first year. It is also helpful to snip new flower buds off the first year or two, if any even develop, so the plant’s energy can be concentrated on developing its root system. Remember: sleep, creep, leap!

Step 5. Pay attention to the original plant. Rebury its roots if any were exposed during the division. Enrich the soil with compost or soil conditioner. Even just loosening it will help; Plants dislike growing in compacted soil. Having some garden soil or compost on hand is helpful but not necessary. It’s okay to add the compost later in the growing year when social-distancing may not be as critical as it is this spring.

Exposed roots of Stokes aster following separation and division. photo by A. Laine.

Follow similar five steps if you wish to relocate a plant: Prepare, survey, dig, replant, nurture. I divided the asters last spring and the new plants are doing very well. I will divide and move some hostas to shadier places this year. My landscape has changed (we took down some larger trees) and the hostas are no longer planted in the right place for their needs.  

Early spring days are excellent for separating, dividing or relocating perennials. And, these are tasks you can accomplish with equipment and material already on hand. Perfect for gardeners sheltering-in-place.

1Perennials not recommended for division

  • Baby’s Breath (Gypsophila)
  • False Indigo (Baptisia)
  • Balloon Flower (Platydocon)
  • Flax (Linum)
  • Bugbane (Cimicifuga)
  • Lupine (Lupinus)
  • Butterfly Weed (Asclepias)
  • Monkshood (Aconitum)
  • Clematis
  • Russian Sage (Perovskia)
  • Poppy

Divide Only to Propagate

  • Bugbane (Cimicifuga)
  • Tall Sedum (Sedum “Autumn Joy“)
  • Garden Peony (Paeonia)
  • Yucca
  • Red-Hot Poker (Kniphofia)

Resources  

1. Some plants need dividing more often than others. Scroll to the bottom of this link for a list of perennials and their division requirements.
https://extension.psu.edu/dividing-perennials

http://chemung.cce.cornell.edu/resources/dividing-perennials

Further Reading

A glossary of gardening terms
https://content.ces.ncsu.edu/extension-gardener-handbook/glossary

The many ways to propagate plants are described in the Extension Master Gardener Handbook: https://content.ces.ncsu.edu/extension-gardener-handbook/13-propagation#section_heading_5641

April: To Do in the Garden

by Gary Crispell, EMGV

Welcome to April in the age of pandemic. Who knew two months ago that we’d all be practicing “social distancing” (though a friend opined that we’re really practicing physical-distancing and e-socializing), sheltering-in-place from an invisible invader and dealing with a shortage of toilet paper? BTW, my sister suggested that those of y’all who do needlework should knit or crochet granny squares to make up for the shortage of TP. Talk about sustainable. And what a great time to be a bidet salesperson!

Oh, wait. This is supposed to be about gardening. My bad. At my age it is easy to get distracted. Did everybody enjoy the March-in-North Carolina weather roller-coaster? I think it does that so that we will appreciate April and May more. So, while we’re all confined to our own yards, (Surely “stay home” doesn’t mean “hide in the house with the covers pulled over your head!?!) let’s go garden.

Lawn Care
Go ahead and fertilize the warm season grasses (Bermuda, zoysia, centipede). They will be breaking dormancy soon and will be grateful for the feed.

STOP fertilizing cool season grasses (tall fescue, bluegrass) unless you want to invite a host of fungal diseases to spend the summer decimating your lawn.  Just sayin’.

Climate change may have made it too late to apply crabgrass preventer this year. The marker is to apply before the dogwoods bloom (usually mid-April), but mine have already begun to open.

Warm season grasses can be planted by mid-month. Seeding is possible, but not recommended.  Sodding and plugging are the preferred methods. NC State’s Turf Files website is an excellent resource for information on all things grass in North Carolina. See resources below.

Fertilize
Any shrubbery that you didn’t get around to in March. See also: Lawn Care.

Planting
It is time to get giddy in the garden! The average last frost date in Durham, NC is April 13, give or take 12 days. I suspect this year it was in mid-March. So, put on those knee pads and plant, plant, plant.

From seed: melons, squashes, pumpkin, beans, cucumbers, corn (okra at the end of the month). Transplants:  tomatoes and peppers. Hopefully your soil has already been amended according to the recommendations of your soil test 🙂 Please plant enough to share with those who may not have any, especially this year because that might be a neighbor who works in a “non-essential” industry. 

Pruning
Remove winter damage from trees and shrubs.

Refrain from pruning spring flowering shrubs such as azaleas (Rhododendron x hybrid), lilac (Syringa spp.), forsythia, spiraea, weigelia, etc. until after the petals fall from the blooms, but before the end of June.

Prune fruiting shrubs like holly (Ilex spp.), and pyracantha while they are in bloom so as not to remove all of this year’s berries.

Prune spring flowering trees such as flowering cherry (Prunus hybrids) and redbud (Cercis spp.) only as needed for damage removal and/or aesthetics.

Spraying
Be on the lookout for the following pests: azalea lace bugs, boxwood leaf miners, euonymus and tea scales and hemlock/ juniper-spruce spider mites. Spray only as needed and follow label instructions.

Spray iris bed for borers.

Continue in perpetuity a rose spray program (please consider organic products).

Treat cruciferous vegetables (broccoli, cauliflower, cabbage, etc.) for worms.

Spray squash plants near the base of the stem to control squash vine borers. Continue doing so weekly until June 1 using a pesticide labeled specifically for vegetables.

Spray apple and pear trees with streptomycin while they are in bloom to control fire blight. Apply twice. Once at early bloom and again at full bloom. If the weather is rainy a third application may be desirable.

Begin weekly fungicide applications for bunch grapes.

Begin weekly fruit tree spraying once the flower petals fall. Again, please consider organic products.

Other Stuff to Do to Avoid Spring Cleaning of the House and Garage
Mulch, mulch, mulch. And did I mention mulch? Unless you are a very recent arrival to the area you know that at some point in the coming summer it will be HOT and at some point, it will be DRY and at some point, it will be both simultaneously. Then you will be glad you MULCHED. Mulch will help to mitigate the effects of a Piedmont North Carolina summer and cut down on your water bill.

And, of course, like death and taxes, there will be weeds. Unless there are an overwhelming number of them, pulling is the recommended (and therapeutic) method of removal. Just be sure that if you get down low enough to pull weeds you can get yourself back up because if you need assistance it will require a block and tackle apparatus in order for the assistor to get you up from a distance of six feet.  You don’t want to go there.

Stay healthy. Stay connected. Take care of each other and keep gardening.

Resources and Further Reading
https://content.ces.ncsu.edu/interpreting-freezefrost-probabilities-from-the-national-centers-for-environmental-information

Everything you need to know about lawn care in NC
https://www.turffiles.nscu.edu

About rose fertilizers
https://www.rose.org/post/2018/03/20/a-fertilizer-primer-what-s-in-that-rose-food

If you grow roses, learn more about the Rose Rosette Virus
https://extensiongardener.ces.ncsu.edu/2020/03/rose-rosette-virus-flower-killer/?src=rss

Pruning trees and shrubs
https://chatham.ces.ncsu.edu/the-science-and-art-of-pruning/
https://content.ces.ncsu.edu/pdf/general-pruning-techniques/2014-09-29/general-pruning-techniques.pdf

Gardening Hotline is Open!

While all Durham County offices remain closed for now, you can still get your gardening questions answered by a Durham County Extension Master Gardener Volunteer.  Yes, even volunteers can work from home!

As Extension master gardener volunteers, our mission is to answer questions specific to your gardening needs — and not just questions about growing heirloom vegetables, or prized roses, or rare trees. Master Gardeners are present to answer any and all of your questions pertaining to indoor and outdoor gardening in Durham County. You can expect a research-based, unbiased answer within a reasonable time frame. Answers are often accompanied by links to additional Internet resources.

Call us at 919-560-0528, or send us an email: durhammastergardener@gmail.com.

For updates on specific Durham County Cooperative Extension services visit https://durham.ces.ncsu.edu/ 

— Editor

More Tips for Growing Orchids Indoors

Following Wednesday’s post about growing orchids I learned additional tips from some fellow Durham County Extension master gardeners.

Temperature change aids flowering

“I took the “how to re-pot your orchid” class at Duke Gardens a year ago, reports Jayne Boyer, EMGV. “The president of the Triangle Orchid Society taught it. One gem that he told us was that in order to bloom, Phalenopsis needs a 10-degree change in temperature from day to night. I have two small Phalenopsis plants at work that I have repotted according to his directions and water with lab deionized water twice weekly (they are in clay pots). They are by large windows facing east and since the thermostat is on an outer wall, the temperature does change a lot in the lab. They seem to love this spot and have bloomed every January for three years.”   

Jayne’s mini Phalenopsis. Photo by J. Boyer.

Fertilizing

Personally, I am not a big fan of fertilizing plants – they make their own food, afterall! So, fertilization got overlooked in my original post.

According to the American Orchid Society, a balanced water soluble fertilizer in the range 20-20-20 is safe and beneficial. Feed weekly at half strength or full strength monthly. This is generally good advice for feeding any houseplant. It helps avoid over-feeding.  

The New York Botanical Garden recommends a compost tea as an organic alternative to chemical fertilizers. “Soak a couple of handfuls of compost wrapped and tied in cheese cloth. Steep for a few hours and use the liquid when watering. Do not store compost tea for more than a day.”1

EMGV Catherine Urich swears by an actual tea solution. “I had a couple of drowned orchids and I found that removing all the moss, cutting out the bad roots and potting in new moss and bark nuggets and watering once a week with a weak tea solution has regenerated growth. Tea contains nitrogen and in this case can be used as a fertilizer.”  Her recipe: Using a quart pitcher, add two used tea bags to warm water and let sit for 15 minutes. The water will appear almost clear. Water once a week as normal. “Both orchid plants have grown new leaves and now, four months later, look healthy. It’s so exciting to have a hand in bringing a beautiful plant back to life.”  

Photo by C. Urich

A big drink of water

As I reported earlier, orchids can take more water than would seem prudent so long as they are given ample time to drain, too.  EMGV Beverly Davis has proved that point with her orchid care.

“I picked up my orchids from the clearance rack at a big box store about five years ago,” she explained in an email. “They are in bloom now for the first time! I water once a week for about three hours by submerging them each in a pitcher of water. I never cut the stem. They receive filtered afternoon sun. I never thought they would bloom and then one day, voila!

Beverly’s orchids. Photo by B. Davis.

Footnotes

1. Compost tea
https://libanswers.nybg.org/faq/222809

Additional resources

http://www.aos.org/orchids/additional-resources/phalaenopsis-part-4.aspx

https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/visual-guides/phalaenopsis.aspx

–A. Laine, editor

Learning Orchid Care

by Andrea Laine, EMGV

“Oh no, not another orchid,” I thought with dread as my July dinner guest handed the plant to me with a smile. Little did she know how much this species of plant has challenged me. Sadly, I’ve killed many over the last 30 years, despite the fact that I’m known for my green thumb, especially with houseplants. At least it was a moth orchid (Phalenopsis), the most common orchid in the marketplace.1

I muddled along for a couple of months. By October,  the plant had dropped all its delicate pink flowers (which I had neglected to photograph) and I had cut the stems down to an inch. (It’s questionable whether I should have done that but what is done is done.) Six broad waxy leaves remained. Then, determined not to fail yet another orchid, I headed over to the Triangle Orchid Society’s show and sale at Sarah P. Duke Gardens in early November armed with photos of my plant and specific questions.

Dallas Ingram, an exhibitor from South Carolina who makes pottery containers for orchids (and is also an orchid grower), was happy to field my questions. Later, I also consulted the American Orchid Society website among other resources.

What kind of container does my orchid need?

I was surprised to learn that the holey ceramic pot I had purchased years ago specifically for an orchid, was not recommended. Dallas explained that pots with lots of openings on every side are designed for orchids that grow in very humid home environments, like Florida. The pottery he makes to contain orchids have two narrow vertical openings which he says are just enough. He didn’t try to sell me one of his pots, or even make the suggestion; He said there was no need to change the pot my orchid was already growing in – as long as I watered correctly. 

Let’s talk about watering

My orchid came with watering instructions: do weekly with warm water. A plastic three-ounce shot glass was provided for the task. I know overwatering a plant can be a detriment, but this way didn’t seem to make sense either. Even with a careful attempt to sprinkle a shot of water over all the bark, the water streamed quickly through the container and collected in the bottom of the cachepot, still missing some roots. Dallas gave me permission to use more water so long as I gave the orchid time to drain outside of the cachepot. The American Orchid Society says to avoid salt-softened or distilled water. So, nowadays I share my room-temperature bottled water with the orchid.  

How much light is best?

Dallas was precise in his reply: bright, indirect light equal to 8,000 to 10,000 lumens. He has found the light from East and even West facing windows to be sufficient. The Orchid Society concurs that an East-facing window is best and South and West are sufficient if covered by a sheer curtain.

What’s happening to these roots?

Some roots protruding above and dangling out the bottom of the container looked dead to me – I showed them to Dallas and learned that what I thought was a root was really a root covering (the velamen); it protects the real root which is a narrow string inside this covering. Orchids metabolize slowly and the root covering stores excess food and water for later usage. I had come close to snipping off those “dead” roots, so I was really glad I asked this question.  

“Velamen is a silver-white in color, but becomes transparent when wet, so that when the root is wet it turns green as you are able to see through to the inner structures of the root that contain chlorophyll .” (2) Photo by A. Laine


A surprising piece of information

It is often a challenge to get a flowering houseplant to reflower again and again. I’m inclined, as I think many people are, to treat them as a temporary attraction and then relegate the plant to a back corner or even toss it. But given the price of an orchid plant, tossing it has never felt like a viable option! As it turns out, coaxing a Phalenopsis orchid to rebloom is not a given. The success rate is 50 percent. Given my history of limited success growing orchids (and having none reflower), I find this news comforting.

I was also delighted to find information at the American Orchid Society’s website that was written expressly for people like me; a Novice Phalenopsis Culture Sheet. I’m not a novice at trying to grow orchids, but I am absolutely a novice at succeeding in growing orchids. However, with new, expert advice in hand, lower expectations about reflowering, and, the joyous sight of a new leaf on my orchid, I am enjoying this addition to my houseplant garden.

The joyous sight of a new leaf on my orchid!   


Of Note: The Triangle Orchid Society holds monthly meetings on second Mondays in the Doris Duke Center at Sarah P. Duke Gardens. Meetings feature a speaker and begin at 7:30 p.m. Learn more at http://triangleorchidsociety.org/


Footnotes & Additional Resources

1, 2, https://longwoodgardens.org/blog/2017-01-31/identifying-orchids Identifying orchids is important to understanding what growing conditions they prefer

Tip sheet for novices
http://www.aos.org/orchids/culture-sheets/novice-phalaenopsis.aspx

Where to cut the stem:
http://www.aos.org/orchids/aos-video-library/where-to-cut-a-phalaenopsis-spike.aspx