Episode 20 – Dormancy vs Hibernation and Shrubs That Hit Snooze on Spring

Ground Breaking Banter - Rick

Stacey and Rick discuss plant dormancy and hardiness in winter. Perhaps you’re wondering, are my plants sleeping? Are they okay? Should we feel guilty hibernating indoors while they ride out winter outdoors? Rick says he knows a grizzly that flunked hibernation. It’s because he gave it the “bear” minimum. However, there’s a difference between hibernation and dormancy. During hibernation, an animal’s metabolism slows to extreme levels but the animal does often rouse to change positions, and can come out of hibernation pretty quickly if necessary. Dormancy, on the other hand, is more of a set period that can only be influenced by temperature and daylength. Hence, animals hibernate, plants go dormant. Rick thought it was really “winter-esting!” 

Our houseplants don’t hibernate but they definitely slow down with limited growth during the short daylight hours in winter. That’s why we back off on water and don’t feed them in winter to promote growth. They will get busy when the days get longer.

Stacey and Rick discuss plant hardiness maps organized into hardiness zones for various regions of the country. The first such map with 8 hardiness zones was compiled at the Arnold Arboretum in 1927 by Dr. Alfred Rehder, based on a survey of plants and their survivability in different regions of the country.

Stacey and Rick discuss the Arnold Arboretum with a fun fact: The second Sunday in May (Mother’s Day) every year is “Lilac Sunday”. This is the only day of the year that picnicking is allowed. On Lilac Sunday, garden enthusiasts from all over New England gather at the Arboretum to picnic and tour the lilac collection.

In 1938, Dr. Donald Wyman of the Arnold Arboretum published a new map in a book, that used 40 years of data (1895-1935) from the US Weather Bureau. In 1960, the US Department of Agriculture got into the act, publishing its first map, based on the data from 450 weather stations around the country. The Arnold Arboretum map remained the standard over the 1960 USDA map until 1990, when the US Department of Agriculture, in cooperation with the US National Arboretum updated the USDA hardiness map, using data from between 4,800 to 14,500 weather stations.

Each of the current USDA climatic zones is based on the average minimum winter temperatures. Stacey and Rick discuss how it is an “inexact science” variable based on a host of fluctuating factors. Date of Note: January 25, 2012 (Eleven years ago next week) The USDA released the new version of its Plant Hardiness Zone Map (PHZM), updating a useful tool for gardeners and researchers for the first time since 1990 with greater accuracy and detail. The new map—jointly developed by USDA’s Agricultural Research Service (ARS) and Oregon State University’s (OSU) PRISM Climate Group—is available online at planthardiness.ars.usda.gov.

According to them the industry standard is they won’t know the specifics about zones changing until they have another 30 years of data to go on, but that doesn’t mean they will wait another 30 years as things are changing much faster than in the past.

Why: While we’re on the topic of hibernation, I thought it would be appropriate to cover one of the shrubs that hibernates the longest, and that’s weigela. We’re focusing on one of the best-sellers and highest performers in the entire line of Proven Winners ColorChoice Shrubs, Sonic Bloom Pink weigela, but this is true of all weigela: they are some of the latest flowering shrubs to emerge in spring. In other words, they take a long hibernation but once they’ve begun leafing out, they catch up to everything else pretty quickly and are in bloom by late spring.

Sonic Bloom Pink weigela is a reblooming weigela, so it flowers in that late spring time period, along with other weiglea, but after it takes a little rest to put on new growth, it starts flowering again about six weeks later and the new flowers continue to appear through the first frost. That rebloom is pretty significant, too – some reblooming shrubs offer little more than a few flowers sporadically through summer, but Sonic Bloom Pink puts on a very impressive display through summer. It’s a great way to get easy-care color at an unexpected time of year – your friends and neighbors won’t believe you’ve got a weigela blooming in August!

Who: Sonic Bloom Pink weigela comes to us from the Netherlands, as so many good flowering shrubs before it (‘Limelight’ hydrangea and Wine & Roses weigela, to name two) have as well. But it also comes with kind of a funny story: the breeder, Kees Jan Kraan, was breeding weigela for various traits. Our new plant development team happened to be visiting him in summer, and saw these weigela blooming totally out of season. He just kind of shrugged, because that wasn’t at all what he was going for in his breeding program. Meanwhile, the Proven Winners ColorChoice team knew immediately that a reblooming weigela would be a huge hit! Weigela is very popular in the US and Canada – it has a nostalgic connection for most people, who remember one in their grandparents’ yard, and when it blooms, it’s so covered in colorful flowers that it’s pretty much irresistible when you see it at the garden center.

Sonic Bloom Pink weigela joined the line here with two other plants that were found at the same time: Sonic Bloom Pearl, which has white flowers that age to pink, and Sonic Bloom Red, with red flowers. They are all good, strong rebloomers, but Sonic Bloom Pink is a true powerhouse and its bright color stands out in the landscape like you wouldn’t believe.

How to grow: Weigela are very easy to grow and enjoy: just plant them in full sun (6+ hrs/day) and any well-drained soil. They are generally hardy down to USDA zone 4, though some are slightly less hardy, and generally heat tolerant through USDA zone 8, though again, some are slightly less heat tolerant, particularly variegated varieties like My Monet and My Monet Purple Effect. Weigela bloom on old wood, so should only be pruned immediately after they flower in spring. In the case of the Sonic Bloom series of reblooming weigela, which blooms on both old and new wood, any pruning you wish to do should be done after that spring bloom. Pruning is not necessary for the plant to rebloom, however, like all reblooming plants, you get the best rebloom if you keep the plant actively growing – in other words, free of stress – especially during that period after its spring bloom. This means keeping it well-watered, but not overwatered, and you might also consider an application of fertilizer in early spring, as well as when that spring bloom finishes. This helps it have the energy to put on abundant new growth – the more new growth the weigela creates, the better it will rebloom.

To return to the reason why we are covering Sonic Bloom Pink weigela in today’s show, it’s important to know that it really is one of the latest shrubs to emerge in spring. Every year, we get a bunch of questions in May, asking why everything else in the yard is growing gangbusters but the weigela is just a pile of sticks. That’s totally normal. People seem especially alarmed the first year after they plant a weigela, as they purchased it actively growing, likely at the same time of year that they’re looking at a pile of sticks in their yard. But that’s because of course, growers bring shrubs and perennials into a warm greenhouse early in the season so they leaf out and bloom far earlier than they would outdoors.

Weigela generally offer very good deer resistance, though you will want to protect new and small plants for their first couple of seasons, when that tender growth will be more appealing to deer and rabbits than those that have become woodier and more fibrous. And another piece of great news – weigela are very appealing to pollinators and hummingbirds. They love these classic trumpet-shaped blooms and with Sonic Bloom Pink, you have plenty of flowers to offer them over a longer period. Planting a Sonic Bloom Pink weigela is doing a good thing for you, your landscape, and hummingbirds!

If you are looking for a shrub with big impact over a long time, find a local garden center that sells Proven Winners ColorChoice Shrubs here and ask for Sonic Bloom Pink reblooming weigela.

Gardening Mail Bag - Stacey

Do you have a garden question for us? We’d be glad to help! E-mail us, or click the “contact” tab above. 

Tam writes: I visited Frededrik Meijer garden in West Michigan and noticed they have some fabulous panicle hydrangea – very pretty and producing a lot of pollen, with bees and insects all over it. I like panicle hydrangea (they’re so easy to care for) and I also like to support pollinators, can you please help me and recommend any varieties of panicle hydrangea that can produce a lot of food for pollinators like that?

Yes – the answer lies in selecting a lacecap variety instead of a mophead variety. In the wild, hydrangea flowers are primarily lacecap – in other words, the large, papery florets outnumber the small, starry fertile florets, as in the photo at left below – as this offers a substantial reproductive advantage for the plant. However, when people got involved with plant breeding, they wanted more of those showy sterile florets and fewer of the fertile, so they eventually created mophead varieties, where the sterile florets completely obscure the fertile ones, as in the photo at right below. While many gardeners prefer the big, full look of the mophead, pollinators certainly don’t – they can’t even reach the fertile florets where all the good stuff is. So, provided you select a lacecap panicle hydrangea, like Pinky Winky, Pinky Winky Prime, Quick Fire, or Little Quick Fire, you’ll enjoy visits from plenty of pollinators.

                            Quick Fire, a lacecap panicle hydrangea                                                              ‘Limelight’, a mophead panicle hydrangea

Errol asks: I live in Florida, zone 10, and was wishing I could grow one of my favorite fruits, the raspberry. I would love to grow either them or black raspberries, but I didn’t think that they would grow here because the plants are listed for 4-8. Can you help?

We hate to be the bearer of bad news, Errol, but it’s true: you cannot successfully grow raspberries in Florida. They don’t get the dormancy they need in your hot climate, and are much more susceptible to disease that will severely set back, if not outright kill, the plants. However, take heart! Good raspberries can be found in the grocery store, and you can take advantage of your warm climate to grow an array of very interesting fruits that those of us in the North can only dream of having in our backyards: mangos, cashews, avocados, citrus, macadamia nuts, star fruits, just to name a few. Here’s a great list and reference for you – so many intriguing choices!

Andrea in Florida asks: We recently had a 2 day freeze. My succulents look sad. Are they gone or will they come back?

Few plants take a freeze as indignantly as succulents do. But they can’t be blamed – they are mostly water, so the effect of a freeze is not unlike making ice cubes and then letting them melt in a bag. It’s impossible to say whether your particular plants are goners or not, but we encourage you not to give up on them too soon. Even though most of the plant may look ghastly, it’s entirely possible that its meristem – the point in the center from which all growth comes – is still intact and if so, they will regrow. I’d give them a good six weeks or so of warm weather before determining if they are alive or not, but definitely make sure they don’t experience another freeze during that time, which would surely set back any progress they made toward recovery.

Branching News - Rick

Today’s words of the day are plumule: pronounced ploom-yool, it refers to the embryonic and emerging stem in a seed or seedling; and newfangled, which of course means describes something new and novel. However, we were, as you may be, surprised to learn that this word dates back to the 15th century.

Do you feel guilty about throwing away old garden tools – if, indeed, you even do? Turns out, they don’t make the top ten list of items people report they discard on a decluttering spree. That list includes:

      1. Clothing – 46%
      2. Papers/files – 44%
      3. Books – 29%
      4. Toys – 25%
      5. Hobby equipment or supplies – 25%
      6. Appliances – 24%
      7. Kids’ items – 24%
      8. Furniture – 22%
      9. Sports/exercise equipment – 20%

    As we compile our lists of resolutions aimed at improving physical and mental health in 2023, University of Colorado Boulder research suggests one addition could have a powerful impact: gardening. Funded by the American Cancer Society, the first-ever, randomized, controlled trial of community gardening found that those who started gardening ate more fiber and got more physical activity—two known ways to reduce risk of cancer and chronic diseases. They also saw their levels of stress and anxiety significantly decrease. 

  • Nothing like a good bucket story (why? Because everything else “pails” in comparison!): A Winston-Salem North Carolina man is caught on camera rescuing a deer in distress. The deer was stuck in a paint bucket. He helped pull the bucket off a deer’s head when it was clearly stuck and in distress. The deer is fine, just looking a little “pail”.
  • Cowabunga! Police in Oklahoma put their cowboy skills to the test when a loose cow was spotted wandering outside an Olive Garden restaurant. Officers questioned the cow and learned that the cow had heard about the never ending soup and salad option at Olive Garden. Rick thinks he got lost looking for the “calf”-eteria.
  • Stacey and Rick discuss “Nature Schools” where kids spend the entire day outside learning. Rick says taking English class outside would make him nervous but I guess once you get used to it you’re past tense.