Tuesday, December 18, 2012

Climate Data from Blue Hill Observatory

I love the freedom and creativity involved in designing gardens, trying not to get bogged down in 'rules' and 'guidelines' but looking at each project as a fresh opportunity.  However, I am a bit of a geek at heart and love the science and detective work required to garden.  'Data' is not a topic often covered in gardening and horticultural discussions, but my 'left-brain' wants to come out and stretch its legs.  So, for those who also like to look at graphs, numbers and trends, here is some compelling information from the Blue Hill Observatory at the Blue Hills Reservation in Milton, MA.

The Blue Hill Observatory is home of the "oldest continuous weather record in the United States."  They keep track of lots of meteorological data and some other cool information like local pond freeze/thaw dates and fruit ripening dates.

Before I go any further, I want to be clear that I am not making any political statements for those who may want to infer them from my summaries.  That said, there are some potentially compelling conclusions to be made from trends in the data.  Most of the data collected goes back to 1885, and the temperature data goes back to 1831.

Keeping a good track of rainfall is critical for anyone who cares about plants big and small.  Letting nature water your plants is always better, time-saving, and cheaper than doing it yourself.  While many people these days seem to have some form of automated irrigation for lawns and smaller plants, tracking rainfall over a season is critical for ensuring the health and vigor of your larger plants.  Large shrubs, ornamental trees and larger trees need long deep waterings that an irrigation system or short hand watering just can't provide.

An interesting fact is that the 30-year mean for rainfall has been on a steady rise since 1885, and the last 30+ years have shown an even steeper rise in the 10-year mean.  However, that does not mean that we don't have shorter periods of drought or mini-droughts.  This past July, in a post, Water those ornamentals and trees, they are thirsty, I reminded people that we were in a mini-drought with minimal rainfall and a very low previous winter snowfall.  When this happens we need to get out the hoses and provide a deep, regenerative soaking for our big plants to keep them healthy and happy.  One good deep soaking, keeps moisture in the root zone and helps them through a short stressful period.

If we don't get good snowfall this winter to provide valuable melt in the Spring, we will enter next spring again at a deficit.  As the 2012 graph shows we are 9.36" shy of our 110 year mean for precipitation, that's about a 20% shortfall.  But... in 2011 we were over 20% above the mean.

With the precipitation trends on the rise, it is interesting to note that these increases are coming from rain during the warmer months and not from snowfall.  The long-term snowfall graph reveals that the 30-year mean has deviated slightly above and below, but remains almost exactly at the same level from over 100 years ago.  Any budding meteorologists want to explain this divergence?

Temperature and USDA Zones

Measured temperatures over the past 180 years are rising in our area.  There is no ambiguity with regard to the Blue Hill data, and the USDA this year released a new Plant Hardiness Zone Map and most every zone shifted up a half to a full number. These are the numbers you see on plant tags that say whether the plant is expected to survive in the ground in your area.  Inside 495 but outside of the city is generally zone 6b now.  The semi-tropicals you may buy as annuals for your pots often are often hardy in zones 8, 9 and 10.  You can use plants that have your zone number or lower, however, know that these zones are based upon long term averages and a relatively young plant(without protection) that matches your zone may suffer or die if there are abnormally low temperatures during the winter.  The USDA zones are guidelines for what typically will survive in your area.

The Blue Hill map above is intriguing, if it represented a stock I would buy it on the promise it will be higher over the next ten years.  The next two graphs show that November 2012 was the first time in 21 months that the mean monthly temperature was below its 110 year monthly mean, and that 2012 and 2011 are 3.9 and 3.0 degrees above the 110 year average mean.

One last bit of interesting temperature data from Blue Hill is their tracking of Houghton Pond freeze and thaw dates.  Houghton Pond is a medium-sized kettle pond(like our Winter Ponds here in Winchester) in the Blue Hills Reservation.  It's pretty cool to track this over time, and as you might expect from the temperature data, the pond is freezing later and thawing earlier over time.  For those of us who have skaters and hockey players in our families, we remember last year when we only had one good day of skating on Winter Pond because of the late freeze and terrible slush and freezing rain that ultimately ruined the surface.

I would be interested to know the criteria for determining when a pond is considered frozen or thawed.  The day we skated last year happened only because I was driving by the ponds and saw an unidentified man out in the middle of the pond jumping up and down.  He did not fall in and within an hour we were on the pond with 50 other people.  While this technique may be effective, it could lead to some longevity issues. 
Alex(in black) and a friend skating before the big pick-up game happened
during the only skating day on Little Winter Pond last season.

Other Interesting Information

A previous post covered a critical horticultural measure called Growing Degree Days.  All plants and insects live their lives not on a chronological calendar like humans, but a temperature-based calendar.  When average daily temperatures creep above 50 degrees, the world comes to life in the spring, flowers and fruits appear based upon the accumulation of the degree days.  Blue Hill tracks when the first Blueberries ripen in the area.  Again, as you might expect with the warming temperatures and an understanding of Growing Degree Days, since 1885 the trend is that Blueberries continue to ripen earlier in the year.  Of course, this is far less scientific than tracking temperature since there may be other factors involved in the process, but fun to look at nonetheless.

Now, for total data overload you can go to NOAA (National Oceanic and Atmospheric Administration) and look into just about any bit of weather information you could imagine.

Thursday, December 13, 2012

Evergreen Perennials In New England, Not Just A Flower!

I started working professionally in the horticultural field while living in Northern California, and the range of evergreen plants and perennials was unbelievable.  Without the freeze, plants and gardens could look great year-round.  There was always a down period in the winter, but that is when I picked my Meyer Lemons and Clementines.  Many of the wonderful sub-tropical annuals that we use in New England are actually perennial in warmer climes like California and some can deliver year-round interest.

So often we think of perennials in New England as plants that flower in the summer and then leave big gaping holes in our garden, but it doesn't have to be that way.  Following are some images and summaries of perennials that deliver during the off-season too.  It is not an exhaustive list...just some of my favorites.  These plants are great to use around entrances and walkways where there is year-round traffic and a desire to keep the gardens interesting and not beds of mulch.

Heuchera v. 'Citronelle' in front of Epimedium grandiflorum
Epimedium grandiflorum 'Lilafee' (Barrenwort)
Another BFF perennial that has delicate, early flowers and has rugged foliage that often goes through a range of colors during the season.  Here it turns a nice bronzy-red in the fall.  This image was also taken a few days ago.  Another great plant for massing as it spreads and looks great most of the year until  it flowers early in the spring and sends out a new flush of foliage.  It prefers shade, but will perform in all but the hottest sun.

Alchemilla mollis
Alchemilla mollis (Lady's Mantle)
This is one of my favorite perennials for its versatility, as I have mentioned before, and it looks good until the snow covers it up.  Not the sexiest plant, but in groupings it spreads and self-sows and has beautiful scalloped leaves.  The chartreuse flowers are fantastic and last for two months in the late spring.  This image was just taken in December and they really keep space filled in the beds when most other perennials have been gone for a month or two.  It performs in shade and sun and will need ample moisture if in a hot sunny space.  The flower display will dissipate in deep shade.

Silver Scrolls in mid-December
Coral Bells have been around forever, and many have been of marginal quality, but I love the new villosa hybrids that are quite vigorous.  The Citronelle plants above, in front of the Epimedium, were small divisions in the early summer and quickly became full-sized.  There are so many shades and colors to choose from (some are quite unnatural looking) that they form great masses of foliage with varying textures.  If you trim them up a little they will look great all year and they do well in sun to shade but prefer a little shade.

Dianthus in front of the border
Dianthus gratianopolitanus 'Firewitch' (Pinks)
Dianthus is a full sun-loving perennial that carries its grass-like foliage year round.  Many of the newer cultivars will flower throughout the season after their big spring flush.   Don't spend much time caring for this plant, it seems to thrive in hot sun and dry soil.  Cut back the spent flowers and it will spend some energy on its foliage and flower sporadically.  Great edge of the border plant and along walls and pathways as it spreads and spills over.  This picture was taken yesterday.

Helleborus orientalis in Bloom (Van Berkum)
Heleborus orientalis 'Royal Heritage' (Lenten Rose)
This is such an under-utilized perennial that can look great during the off-season and flowers early in the year with the spring bulbs.  It takes a little time for these plants to get established, but when they are, the glossy, leathery foliage is a wonderful textural addition to the perennial bed.  They come in a broad range of colors from white, yellow, pink and reds to maroon and 'black'.  The above link refers to a comprehensive article on Hellebores by Plant Delights Nursery, one of the finest perennial nurseries in the country.

Bergenia turning in fall (Van Berkum)
Bergenia cordifolia (Pigsqueak)
You have to love a plant with the common name of Pigsqueak.  Another decidedly un-sexy plant, but it forms wonderful mats of heart-shaped(cordifolia means heart-shaped foliage) leaves, when planted in groups. The foliage turns a bronzy color in the fall.  It also flowers early in the season with the spring bulbs, and prefers a fair bit of shade in woodland settings.  A nice surprise for those who think perennials are just for the summer.

Sedum reflexum a blue and yellow  (Stonecrop)
There are so many forms of Sedum, from the upright stalwarts of the fall garden to the creeping evergreen groundcovers here.  These have been in their stone container outside for five years and look great with an occasional clean-up.  In sunny beds they will form beautiful mats of foliage year round.  They all have a great flush of flowers in the summer to add to an already interesting foliage plant.  They like it hot and dry and thrive on neglect. Who would want more!

When designing with perennials, we are always looking for the color and pizazz they provide, but often we overlook the value their foliage can provide, especially in the off-season when most perennials are in dormancy.  These good foliage traits can allow you to use perennials in the most visible areas and not worry about holes in your beds in the off-season.  Often these plants are at their worst in the spring, but if you intersperse with spring bulbs, they will take your eye off the plants as they regenerate for the new season.

Pieris x 'Browers Beauty' a favorite shrub in Fall and Winter
for it flower buds that will open in spring and the foliage color

I loved this photo from two weeks ago of Acer griseum in color by
the front door.

Monday, December 10, 2012

What are these Moths doing out in December?!

Male moths hanging around a light at night.
Have you been driving around recently wondering what these drifts of bugs are flying in your headlights?  Shouldn't everything be asleep for the winter... well, not the aptly-named Winter Moth.  This is one of many introduced (non-native) predators that are attacking our local, native and landscaped trees.  While it is possible that these little winged beasts could defoliate and kill our trees, mostly they cause slightly less but still significant damage. So many people I talk to say, "do I really have to pay someone to take care of this?"  The answer is yes.

Winter Moth Fact Sheet (UMass)

Close-up of a male.  Identified by the vertical dark
banding at the bottom of the wings and the
frilly edges.
If you are in a town like Winchester MA, most of the trees were planted long before you were born, and many before your parents were born.  In today's world, we often have such a short-sighted view on that which surrounds us, but as we look at trees, we have to realize that their existence crosses generations and that we need to care for them for future generations to enjoy.

Often, prior to some simple education, I find people are reticent to spend much effort or money to care for their trees, but with a proper arborist and relatively minor annual expenditures, you can be rewarded with healthy and vigorous trees.  Some of these expenses, like pruning, are elective, but some challenges must be handled or the life of your trees can be threatened.

One such threat here in northern New England is the aforementioned Winter Moth (Operophetera brumata).  The moth looks, and is, benign, but the caterpillar in its earlier life stage is what causes such incredible damage.  This insect, introduced from Europe, has caused some real problems in Massachusetts in recent years.  Early in the Spring at about 50 Growing Degree Days(GDD), eggs hatch and small larval caterpillars seek shelter in swelling tree leaf buds.  They then grow by eating the tender, young leaves.  An infestation becomes evident when leaves emerge skeletonized or half eaten.

Most trees will send out a new set of leaves after the pests have rappelled on their silk to the ground, but this new leaf break takes tremendous energy reserves and over a few seasons of attack can wear down even the oldest and strongest of trees.  Young trees, especially fruit trees, can be defoliated and killed in just a few seasons.  The big targets for Winter Moth are Oak, Maple, Ash, Birch trees, but they love all plants in the Rosaceae family (Rose), which include many fruits like apple, crabapple, plum, cherry, Amelanchier and Hawthorn among others.

Physical barrier to keep females from climbing tree.
If you have lots of moths hanging around your outside lights or on your windows, you should contact an arborist and schedule spray treatments for next Spring.  The current applications for this pest are very targeted and not toxic, so you don't have to worry about non-specific chemicals being used and polluting your property.  Ask you arborist about this and they will gladly discuss the treatments.

There is also a physical, non-spraying option where a sticky band is wrapped around the tree and stuffed with a padding material to physically keep the females from getting from the ground up the tree.  It works, but in bad infestations these bands can get filled with moths which allows other moths to walk right over them.  The photo to the right shows a band from a local tree with just a few captured moths.

A female moth I found at night in a stand
 of trees by a local pond.
The life cycle of the Winter Moth is pretty cool.  In the late fall, usually after Thanksgiving, when we have a slight warming the male and female moths emerge from the soil.  The male moths have wings and they are the ones you see flying in front of your car and on your outdoor lights.  The females have minuscule wings and are not able to fly, so they come out of the ground and crawl up the trunks of trees where they are found by the flying males after they emit a powerful pheromone attractant.  The females then lay their eggs on the branches or trunk and die.

In early spring as the leaf buds start to swell, the larvae hatch and crawl into the leaf buds and eat their hearts out.  People have said that in bad infestations, you can hear the millions of caterpillars munching away.  If you are parked under an infested tree in early spring as leaves start to emerge, you car will be covered in little caterpillar poop that look like tiny poppy seeds.  Soon thereafter the inch long green caterpillars return to the ground and wait until the fall to emerge again.

Because this pest is introduced, there are no natural predators to control their unmanaged expansion, which is why we need to bring in people to manage them for us.  However, there is a parasitic fly native to Europe that controls populations there and has been introduced and been successful in Canada.  Currently people locally are breeding and introducing these flies here in an effort to control the moth.

If you live locally and have noticed these moths recently, please contact a well-regarded local arborist and have them assess your property for trees that host the Winter Moth.

A friend asked me the other day if they needed to worry about these moths getting into their house and eating holes in their nice natural fiber clothes, especially wool sweaters.  The answer is a simple no.  It is not a moth that eats your clothing but the newly hatched caterpillar.  This Winter Moth flying around is male, the females have no wings, and they do not eat in their short life cycle, and since, as males, they cannot lay eggs, you have no worries about any offspring eating your clothing.