Hardy palms of Rehoboth Beach

My husband and I spent a pleasant long weekend in Rehoboth Beach, Delaware earlier this month.  We love going to the beach during the off-season, not only because it's cheaper, but because it's a whole lot less crowded; we love being able to find parking and not having to wait for a table at a restaurant.  Rehoboth Beach is beautiful in early October and if the weather cooperates, the water is still warm enough to swim.

Because of its proximity to the ocean, the climate is much more moderate than my own in Washington, DC; the summers tend to be a bit cooler and the winters a bit warmer, making the climate ideal for growing hardy palms like Trachycarpus fortunei.  A few adventurous Rehoboth Beach gardeners have been trying windmill palms and I've been following some of these for several years.  But the beach is by no means immune to cold weather and this past winter the palms of Rehoboth Beach were put to the test by the east coast's coldest winter in 20 years.

Washington windmill palm winners (and losers)

Scottish Rite Temple, October 2012

In early February, when we were in the middle of our coldest winter in a very long time, I wrote a blog post rounding up several windmill palms (Trachycarpus fortunei) that I've encountered in the city.  Most of these palms were several years old and had suffered little damage from our recent mild winters but as I wrote in February, "...our coldest winter in 20 years will surely put these palms to the test.  A general rule of thumb is that single digit temperatures are likely to cause damage, and temperatures below zero will cause massive damage and in many cases kill the palm outright (although duration of the cold is also critical).  This makes windmill palms marginal in zone 7: sooner or later, they will experience temperatures capable of killing them."

What's missing from this picture? (Hint: palms)

Garden, late August 2014

What's missing from this picture?  Those of you who have been following my blog since last year (or who read the post title) probably have a good idea.  But this photo from the same time last year really brings it home:

Southeastern Palm Society summer meeting

Southeastern Palm Society members

Members of the Southeastern Palm Society were treated to a meeting last weekend at Plant Delights Nursery and Juniper Level Botanic Gardens in Raleigh, North Carolina.  It had been several years since my last SPS meeting, and I'm always looking for any excuse to visit Plant Delights, so I decided to drive from Washington, DC to Raleigh to attend the meeting.  (I was fortunate to make it in 5 1/2 hours this trip.  I've made the trip in 4 1/2 hours, but once it took almost 8 hours.  The less said about I-95 through northern Virginia, the better.)

Recovery

This has been a bit of an odd spring for me and my garden.  After my area's coldest winter in 20 years, here it is the last day of May and I'm still waiting to see what survived and what didn't.  Many plants that I thought for certain were dead and gone are finally showing signs of life, so in the meantime I'm trying not to disturb plants that may or may not be alive.  For example, just a few days ago I decided to transplant something, and accidentally uncovered a begonia that was sending up a strong new shoot from deep underground.   Just this morning I discovered hardy elephant ear Colocasia 'Pink China' finally coming up, and two new shoots on my hardy banana (Musa basjoo).

So I'm holding off a bit on planting new plants, although it's killing me not to fill the gaps left in my garden by dead or badly damaged plants.  (You can see in the photo above my recovering windmill palm at lower left, and a seemingly dead fig at upper right).   I've also lost much of my shade, so I'm not certain where to plant the gazillion potted begonias from my breeding program that need to get into the ground soon.  My window to get everything planted, before summer heat, humidity, and mosquitoes make gardening unbearable, is rapidly closing.  At what point should I declare plants dead and plant new ones in their place?

It will be quite a while before my garden is anywhere near back to normal, and it will look nothing like last year's garden.  That's the nature of this hobby; every year is different, and our creations grow and change, sometimes in the ways we planned but often in ways we never expected. 

Spring has sprung

Iris 'Buckwheat'

What a relief that spring is finally here!  In fact the last 3 days have felt more like summer, humid and with highs close to 80.  In addition to the spring perennials cheering me up, I'm seeing recovery on several plants that were badly damaged by the winter and that I thought (or feared) were dead.  To recap, this was the Washington, DC area's coldest winter in 20 years, and was a good test of all the marginally hardy plants we're growing here!  The low in my own yard was about 5 degrees in early January, with several more lows in the 9-12 degree range and several periods of temperatures well below freezing.

Survival of the fittest?

   
Garden, early December (left), mid-April (right) (click on photos to see larger version)

This side-by-side comparison shows very graphically how bad a hit my garden, and especially my palms, took after this winter.  The photo on the left was taken in early December, after a hard freeze had knocked down the hardy banana (Musa basjoo) but before the series of cold waves we had in January.  The photo on the right was taken just today; daffodils may be blooming merrily but not much else is looking good!  Note the windmill palms: Trachycarpus fortunei "Bulgarian" in the lower left, T. fortunei "Nainital" at upper right, and T. wagnerianus immediately to its left.

Bulgarian wins!

I've been trying to put together a blog post with some photos I took over a week ago, but right now I have to share this photo that I took just a couple of hours ago.  A few weeks ago I asked the question, Is my palm dead?  For at least one of my palms, the answer is no!

Is my palm dead?

Garden, mid-March after our coldest winter in 20 years

Is my palm dead?  Lots of people are going to be asking that question over the next few weeks because frankly, the palms look dead.  The short answer: maybe, maybe not.  Hardy palm legend (and mystery author) Tamar Myers supposedly once said, "don't declare a palm dead until spring, and don't declare one alive until summer."

Why bother?

Trachycarpus wagnerianus after our coldest winter in 20 years

Just as many growers of hardy palms are wondering whether our palms will survive our coldest winter in 20 years, and whether it's even worth growing them, I came across this in the Plant Delights Nursery February 2014 e-newsletter:

Speaking of weather, winter 2013/2014 has been quite an event in many parts of the country, with temperatures finally returning to more "normal" winter levels. We've amusingly watched the last fifteen years as zone creep, aka: zone denial, has taken hold of much of America. It's been fascinating to observe how quickly peoples' memories of hard winters fade when they are only a couple of years removed. Some gardeners have recently admitted being lulled into a false sense of security by the constant media drumroll that our climate has dramatically warmed forever.

Gardeners in Zone 4 or 5 have a few Zone 7 winters where the winter low temperatures don't drop below 0 degrees F, and all of a sudden they decide that Zone 7 plants will actually survive in Zone 4 and 5. It's not uncommon these days to find less than reputable online nurseries listing plants like the hardy banana, Musa basjoo, as hardy to Zone 4 and 5, which is pure insanity. Windmill palms, which we consider marginally hardy for us here in Zone 7b, have now been planted throughout the mid-Atlantic states and even into parts of the Midwest. Because of the recent mild winters, some windmill palms have actually achieved good size before this winter's reality check. My friend Al Hirsch recently reminded folks on one of the hardy palm groups that he had actually freeze-tested windmill palms in the lab, and 5 degrees F was their low temperature tolerance...except for some of the hardier forms. Just because we've had a string of mild winters doesn't mean the winter temperature tolerance of plants change.

Tony Avent is a global warming skeptic, and I disagree with him on that subject (and one cold winter doesn't disprove global warming!).   But I agree with his main point here: many people have been fooled into thinking certain plants are hardier than they really are, because we've had some unusually warm winters for the last decade or more.  I've seen claims that Musa basjoo is hardy to zone 4, and that windmill palms (Trachycarpus fortunei) are perfectly hardy in zone 7, but pretty much anything is "hardy" with a warm enough winter, or if you provide enough protection.

I don't think anybody is suggesting we should stop growing hardy palms or subtropicals, or anything that might be marginally hardy.  I'm certainly not, and I don't think Tony Avent is either, as he makes a lot of money from selling them to us!  But we shouldn't expect (or pretend) plants to be hardier than they really are.  Winters like this one do happen periodically, they will kill (or severely damage) marginally hardy plants, and for those of us in zone 7, windmill palms are among those marginally hardy plants.  

My own attitude has always been that it's fun to grow plants like this and we should do it if we want to!  But we should go into it with realistic expectations, and should expect to either protect or lose our plants when winters like this one come around.  And we need to communicate those limitations and expectations when we advise or encourage people to grow plants like this.

So are all of our windmill palms in the Washington, DC area dead?  I don't think so.  It's still too early to be sure, but I'm willing to bet that at least a few of the local palms, especially those planted in sheltered locations, will pull through.  Many of us are growing palms from reputedly extra-hardy strains, so it will be interesting to see if that makes any difference.  And regarding Al Hirsh's work, he was testing temperatures that are lethal to leaf tissue under laboratory conditions; whether those same temperatures would kill the same palm growing outdoors is another matter, certainly tied directly to the duration of the low temperatures, which affects how deeply cold penetrates into the trunk, where the meristem (growing point) is deeply buried.  Windmill palms are famous for bouncing back after suffering massive damage from winter freezes, so no matter how bad those palms may look this spring, don't give up hope!  Doesn't a view like this make it all worth it?


Garden, early October

Speaking of weather, winter 2013/2014 has been quite an event in many parts of the country, with temperatures finally returning to more "normal" winter levels. We've amusingly watched the last fifteen years as zone creep, aka: zone denial, has taken hold of much of America. It's been fascinating to observe how quickly peoples' memories of hard winters fade when they are only a couple of years removed. Some gardeners have recently admitted being lulled into a false sense of security by the constant media drumroll that our climate has dramatically warmed forever.
Gardeners in Zone 4 or 5 have a few Zone 7 winters where the winter low temperatures don't drop below 0 degrees F, and all of a sudden they decide that Zone 7 plants will actually survive in Zone 4 and 5. It's not uncommon these days to find less than reputable online nurseries listing plants like the hardy banana, Musa basjoo, as hardy to Zone 4 and 5, which is pure insanity. Windmill palms, which we consider marginally hardy for us here in Zone 7b, have now been planted throughout the mid-Atlantic states and even into parts of the Midwest. Because of the recent mild winters, some windmill palms have actually achieved good size before this winter's reality check. My friend Al Hirsch recently reminded folks on one of the hardy palm groups that he had actually freeze-tested windmill palms in the lab, and 5 degrees F was their low temperature tolerance...except for some of the hardier forms. Just because we've had a string of mild winters doesn't mean the winter temperature tolerance of plants change.
- See more at: http://www.plantdelights.com/index/page/static/subpage/Newsletter_2014February#sthash.Y8cauiMu.dpuf

Speaking of weather, winter 2013/2014 has been quite an event in many parts of the country, with temperatures finally returning to more "normal" winter levels. We've amusingly watched the last fifteen years as zone creep, aka: zone denial, has taken hold of much of America. It's been fascinating to observe how quickly peoples' memories of hard winters fade when they are only a couple of years removed. Some gardeners have recently admitted being lulled into a false sense of security by the constant media drumroll that our climate has dramatically warmed forever.
Gardeners in Zone 4 or 5 have a few Zone 7 winters where the winter low temperatures don't drop below 0 degrees F, and all of a sudden they decide that Zone 7 plants will actually survive in Zone 4 and 5. It's not uncommon these days to find less than reputable online nurseries listing plants like the hardy banana, Musa basjoo, as hardy to Zone 4 and 5, which is pure insanity. Windmill palms, which we consider marginally hardy for us here in Zone 7b, have now been planted throughout the mid-Atlantic states and even into parts of the Midwest. Because of the recent mild winters, some windmill palms have actually achieved good size before this winter's reality check. My friend Al Hirsch recently reminded folks on one of the hardy palm groups that he had actually freeze-tested windmill palms in the lab, and 5 degrees F was their low temperature tolerance...except for some of the hardier forms. Just because we've had a string of mild winters doesn't mean the winter temperature tolerance of plants change.
- See more at: http://www.plantdelights.com/index/page/static/subpage/Newsletter_2014February#sthash.Y8cauiMu.dpuf

Speaking of weather, winter 2013/2014 has been quite an event in many parts of the country, with temperatures finally returning to more "normal" winter levels. We've amusingly watched the last fifteen years as zone creep, aka: zone denial, has taken hold of much of America. It's been fascinating to observe how quickly peoples' memories of hard winters fade when they are only a couple of years removed. Some gardeners have recently admitted being lulled into a false sense of security by the constant media drumroll that our climate has dramatically warmed forever.
Gardeners in Zone 4 or 5 have a few Zone 7 winters where the winter low temperatures don't drop below 0 degrees F, and all of a sudden they decide that Zone 7 plants will actually survive in Zone 4 and 5. It's not uncommon these days to find less than reputable online nurseries listing plants like the hardy banana, Musa basjoo, as hardy to Zone 4 and 5, which is pure insanity. Windmill palms, which we consider marginally hardy for us here in Zone 7b, have now been planted throughout the mid-Atlantic states and even into parts of the Midwest. Because of the recent mild winters, some windmill palms have actually achieved good size before this winter's reality check. My friend Al Hirsch recently reminded folks on one of the hardy palm groups that he had actually freeze-tested windmill palms in the lab, and 5 degrees F was their low temperature tolerance...except for some of the hardier forms. Just because we've had a string of mild winters doesn't mean the winter temperature tolerance of plants change.
- See more at: http://www.plantdelights.com/index/page/static/subpage/Newsletter_2014February#sthash.Y8cauiMu.dpuf

Waggie vs. Nainital

Trachycarpus wagnerianus (left), T. fortunei "Nainital" (right)

Not all windmill palms are created equal.  In fact there seems to be quite a bit of variation in cold hardiness among them, with some selections or strains reputed to be hardier than others.  The above photo illustrates very clearly such a difference.  Many sources claim that "waggies"--Trachycarpus wagnerianus, which is probably no more than a dwarf version of T. fortunei that arose in cultivation--are among the hardier windmill palms.  In fact, that's why I ordered seeds of this species 13 years ago, when I was just starting to get into hardy palms.  But after this winter, I'm not so sure about that.

The windmills of Washington

For the last two decades, some of the more adventurous gardeners in the Washington, DC area have been planting Trachycarpus fortunei, commonly known as "windmill palm".  Although the dwarf palmetto (Sabal minor) and needle palm (Rhapidophyllum hystrix) are considerably hardier, the windmill palm is the hardiest of the palms that grow trunks and can properly be called "palm trees".  Exactly how hardy is still a matter of debate, and our coldest winter in 20 years will surely put these palms to the test.  A general rule of thumb is that single digit temperatures are likely to cause damage, and temperatures below zero will cause massive damage and in many cases kill the palm outright (although duration of the cold is also critical).  This makes windmill palms marginal in zone 7: sooner or later, they will experience temperatures capable of killing them.

Duration, duration, duration

Garden at the end of January

When I give talks about growing hardy palms or other marginally hardy plants, one of my talking points is "location, location, location".  My point is that I live in a city, so I benefit from an urban heat island that keeps me quite a bit warmer than the surrounding suburbs.  In addition, there are microclimates within the city, and even within our own yards, that can add or subtract up to a half zone of hardiness.  For example, my property is on a north-facing slope that receives no direct sun from mid-November to mid-January; overnight low temperatures in my yard are nearly always several degrees colder than the "official" temperatures for Washington, DC as recorded at Washington National Airport (which, ironically, is not even in DC!).  This morning the official low at DCA was 16 degrees, but at 4:00 am the temperature in my yard was 12 degrees.

The saga of the Scottish Rite palms

Scottish Rite Temple, December 2009 (Photo: Kenneth Fletcher)

In summer 2009 an interesting thing happened.  The Scottish Rite Temple on 16th Street in Washington, DC--just blocks from where I live--had new landscaping installed that included two good-sized palm trees flanking the front entrance.  The palms were palmettos, Sabal palmetto, a species native to the southeastern USA.  This had various palm growers scratching our heads; were they meant to be permanent?  If so, they were a poor choice as this species isn't hardy in zone 7, and planting so late in the growing season would give them insufficient time to establish themselves before winter.  But if they were meant to be temporary plantings, it seemed rather expensive and extravagant.

Freeze-dried palms and other garden delights

Fronds of Trachycarpus wagnerianus after an extended freeze

Things are not looking good in the garden.  After several days of temperatures well below freezing, I was hoping for a bit of a thaw this weekend but after an initially promising forecast on Friday was revised downward, and my thermometer read only 30 degrees at 4:00 pm yesterday, I think that's as good as it's going to get.  The latest forecast for today is 30 degrees, and 39 degrees tomorrow, but I'll believe it when I see it.  Monday will mark a full week of temperatures below freezing.

It was @!#$% cold last night!

Curled leaflets on a Trachycarpus wagnerianus frond at 5.2 degrees

After several days of practically apocalyptic forecasts, I spent last night listening to the wind and wondering just how cold it would get.  After a rainy and fairly warm morning, at around 5:00 pm the wind had picked up, the temperature started dropping rapidly, and by this morning, local airports had recorded our area's lowest temperatures since 1996.  At 8 am, the official low temperature at DCA (Washington National Airport) was 7° F (-13.9° C) but in my own back yard, the temperature was 5.2° F (-14.9° C), the coldest I've had since buying this property in December 2000.  The next coldest I've recorded was 6° F (-14.4° C) in January 2004.

To broom or not to broom, that is the question

Palm fronds bending under the weight of snow

Thursday night saw a rapid drop in temperatures accompanied by snow that is still sticking around, including on my palms!   The standard advice is to use a broom to gently knock snow and ice off palm fronds to help prevent breakage or other mechanical damage, but I've been going back and forth on whether to do this.  My reasoning is that the snow might actually help prevent desiccation from cold winds, especially as temperatures drop the next few days.  I could be absolutely wrong, but with lows forecast to go into the single digits last night, I figured the damage was already done and I might as well leave it.  As it turns out, the low last night in the city was 18 degrees--several degrees higher than the warmest forecast and certainly nothing to be concerned about--and it's going to warm up enough tomorrow that all the snow will probably melt or fall off on its own anyway.  And then comes Monday night!  I'm still wondering how my palms will fare if it really goes into the low single digits as they're predicting, but who knows, the urban heat island just might save my ass one more time!


Windmill palm (Trachycarpus fortunei) with snow

Is this the apocalypse?

Forecast lows for Monday night/Tuesday morning (source: Washington Post)

A few days ago I wrote about a major cold wave pouring south from Canada.  The weather forecasters are starting to talk in apocalyptic terms, telling us that this event is likely to give us our lowest temperatures in 20 or maybe even 30 years.  A story in yesterday's Washington Post states, "Some of the coldest air in years, if not decades, is poised to pour into the U.S., with mind-boggling low temperatures.... it’s possible all of the I-95 cities from D.C. to New York City drop below zero [= -17.8 C] for the first time in nearly 20 years." 

The last time Washington, DC had temperatures like that was February 1994 when we had -4 F (-20 C).   Many windmill palms (Trachycarpus fortunei)--including my own--have been planted in the Washington, DC area since 1994.  Monday through Wednesday will be a major test for them and for many other plants that people have convinced themselves are perfectly hardy here!  The coldest my own garden has seen since 2000 (when I purchased the property) is 6 degrees F (-14.4 C) in January 2004, and I think it may get colder than that on Monday night.  I did cover my Schefflera delavayi because it's a long shot in my area, and also because I planted it rather late in the growing season.  My other concern is Cycas panzhihuaensis, which has been in the ground for several years and has survived single digits on more than one occasion, but has been declining gradually since I transplanted it about 4 years ago.



Cycas panzhihuaensis in January 2013

Causes for concern are that (a) we we are forecast to have two very cold nights in a row, with the daytime high staying well below freezing during that period; and (b) this cold is coming early in the winter, so any damaged plants will have to wait several weeks before they can recover.  Another cause for concern is that I have a cold microclimate within the city; while I do benefit from the urban heat island compared to locations outside the city, low temperatures in my garden are often several degrees lower than the official low at DCA (Washington National Airport) several miles away.  The good news is that temperatures are supposed to be well above freezing both immediately before and immediately after this event, so the soil shouldn't freeze very deeply.  That should make a big difference because when roots freeze, all bets are off!

Single digits next week?

Trachycarpus wagnerianus at 8 degrees (F) in January 2009

Cold weather is sweeping south from Canada later this week, with temperatures in Washington, DC possibly dropping into the low teens (F) by Saturday, and maybe even into the single digits next week.  Personally, I don't trust any weather forecast that's more than 3 or 4 days away.  But let's face it, this is winter, and winter gets cold!  We've been very lucky the past few years, with warmer-than-average winters, and sooner or later winter has to catch up to us.

These would be the coldest temperatures my plants have experienced since January 2009, when I recorded 8 degrees (F) in my back yard.  After that cold spell, several of my hardy palms suffered serious damage.  The first sign of trouble was the freeze-dried appearance of the fronds of Trachycarpus wagnerianus (as seen in the photo above).  These fronds ended up dying and the plants were nearly defoliated.  None of them died outright, putting out new growth the following summer, and fortunately we had a series of warmer winters after that, with nothing lower then the mid-teens.  Even so, two of my "waggies" were so weakened that they succumbed to the following winter, even though it was considerably warmer.  The one survivor has put out very strong growth since then, possibly because they were planted too close together and its competition was eliminated!  Here is how it looked in October 2012, next to Trachycarpus fortunei "Nainital" (which has proven much hardier for me and sailed through the 2008-2009 winter with minimal damage):


Trachycarpus wagnerianus (left), T. fortunei "Nainital" (right)

I always have mixed feelings about these winter forecasts.  On the one hand, I don't want to lose any plants, especially not palms that I've grown from seed or otherwise invested with a decade of cultivation.  On the other hand, I want to find out how hardy they really are, and protecting them won't tell me that. I made a conscious decision several years ago that I was willing to risk losing the plants and I haven't protected any palms since February 2005, and then only my Trachycarpus wagnerianus as they were still very small seedlings.  None of my other palms have ever received any protection other than a generous layer of mulch.  Frankly, I find it too much work to protect plants and you can see how much effort I put into it for my "waggies":


Sophisticated palm protection, February 2005

Incidentally, this is what my fatsias looked like after the same cold event--believe it or not, they completely recovered from their infamous "fatsia flop" with no damage whatsoever:


Fatsia japonica at 8 degrees (F) in January 2009

Yikes! Ice!

Windmill palm (Trachycarpus fortunei) after freezing rain

As a quick update to yesterday's post, the light morning snow changed to sleet later in the day, and to freezing rain sometime during the night.  And when it comes to palms, ice is the enemy!  Fortunately everything had just a light coating of ice, just enough to bend all the fronds down but no so much as to break them.  But now we have more snow moving in.  After several unusually mild and snow-free winters, maybe this will be the winter to put my hardy palms to a proper test?