Thursday, April 21, 2016

Spring and Tides

We're pointed toward the ocean this month.  Seeing the waves and abundant shore life is some compensation for missing part of garden season back home.

We are musing on a couple different science topics.
Animated real-time global conditions at earth.nullschool.net
One is coastal changes.  Ernie is still passionate about the massive changes that are happening, and likely to increase, along our beautiful coastlines.  It's not just a question of who gets beachfront property; the coast is always eroding, but even a small change in sea levels could massively change the current coastlines, affecting agriculture, fisheries, harbors, tides and currents, and the weather.

While the weatherman may not be able to tell you months in advance which particular spring day will be fair for your wedding, you used to have pretty good confidence in which month to plant peas vs. beans, or use a tide chart to time your way through a tight spot, and know when and where to expect tuna, salmon, or crab season.  Changing ocean currents sometimes move fish runs hundreds or thousands of miles off course (if the fish are surviving at all, which we devoutly hope they are).

In the face of all this change, reclaiming predictability is pretty attractive.  I think that's part of what drove our ancestors to make a religion out of calendars in the first place - Stonehenge, the Celtic sun-mazes, Mayan temples, the Egyptian pyramids, built on carefully-surveyed celestial axes and bearing enduring witness to the passage of the seasons as well as the ambitions of mortal man.

This is not the first time change has confronted us.  Our ancestors lived through ice ages, droughts, floods, fire, and plague; what's a few breadbaskets turning into fjords compared to historic miseries?  But you can see where there is a very strong human resistance to change, and a craving for predictability and reliable rules for dealing with complex things like weather, growing conditions, and morality.


One of the most popular, and misunderstood, elements in nature are the effects of the moon and tides on the living, breathing Earth.  (By which I mean the biosphere: the plants, animals, soils, swamps, reefs, and skintillions of tiny unseen beings who make up the growing, living, dying, feeling skin of this blue planet.)

Many people understand the tides as caused by the moon pulling on the earth.  That's somewhat true (both moon and sun affect tides).  But I think we assume the timing is simpler than it actually is, because we are used to relying on the moon and sun as the main cog-wheels of our calendar.

The waxing and waning of the moon is a great way to set rendezvous and festival dates in low-tech societies, because everyone can synchronize their schedule without a watch alarm.  Rendezvous are not just for wild parties or philosophical societies: the longer "day" can be used for coordinated work like plowing, haying, and harvest home.  Some almanacs or systems such as biodynamics give ever-more-complex ways to organize the growing calendar, defining certain days and even hours as "seed days," "root times," and fallow times. 

Having a schedule that reminds you what kinds of activities you might need to do this week, and helps you pick a time to do them, is very useful, especially in a situation where your normal instincts about weather can lead to undue optimism and early planting. 

However, I get a little twitchy when people justify these schedules because of the "tides" or the "pull of the moon." The majority of calendars reflect the waning and waxing light, and basically ignore the tidal forces.  (The full moon and new moon are both aligned with the sun to produce higher and lower tides, compared with the out-of-alignment quarter moons). 
It's conceivable that the moonlight may affect some types of plants.

But what really prickles me is that this simplified "explanation" for lunar influence, "just like it pulls the tides," ignores how complex and rich a pattern the tides actually are.  The tides are different from one place to another, even from one side of an island to another.

If you don't have any idea of the full complexity of the tides, which after all are basically just sloshing water, how much more are you likely to mis-understand the intricate forces that coax many different kinds of plants to their best growth?

People with woo-woo garden theories nevertheless often have spectactular gardens, possibly due to caring enough to pay close attention to their plants.  "Listening" and "talking" to plants, whether there is any scientific basis for it or not, seems to open the mind up to notice what's needed and support the plants in a timely way.  Sceptics who don't garden are not well-positioned to offer advice.  But it's still annoying to be quoted pseudo-scientific justifications for folk practices, whether they work or not.  There's been a lot of bad science done around biodynamics, in particular: biased studies or compilations that only list favorable outcomes; claiming statistical significance by growing large numbers of seedlings at the same time, but without controlling for other variables like weather or temperature, or by comparison to any other years.  Bad science doesn't disprove a pet theory, but it doesn't prove it either, and it often grates on science-minded ears as an annoying waste of time.

I am not a biology buff, and my garden is far from exemplary. 
But I have been learning about the tides, and it's fascinating.

If you look at tide tables, the most extreme tides are generally at the new moon, when moon and sun's pull line up.  These will be the "spring" tides, both highest and lowest tides.  The full moon has relatively regular tides. During the quarters in between you can get uneven tides where one low or high will be different than the other for that day. 

You can look up tides for different coastal areas here: http://tidesandcurrents.noaa.gov/tide_predictions.html?gid=132  (they can be off by several hours for places under the same moon phase, due to differences in the shape of the bays and basins and coastline.)

The tides don't actually race around the world keeping up with the moon - water waves simply can't move that fast, they would have to go over a thousand miles an hour.  Instead, it's more like a dancer spinning plates, where repeated motions create a sloshing effect.  If you want to play around with this, the easiest (and most fun) way is to sit or lie in the bathtub, then rhythmically flap one hand back and forth in place.  Sometimes nothing much happens.  Sometimes if you hit the right rhythm, the whole tub starts sloshing water out both ends.  If you shift position (sit up, or lie down), the rhythms change.  Your body is like the coastline and undersea shapes that define the basins, or "bathyscape."  Your flapping hand is like the regular pull of sun and moon, working the waters into a sloshing rhythm.

The ocean tides get nudged into circular currents, or sloshing extremes, or pivot points of near-perfect stillness, based on the shapes of the continents and ocean basins.  Some areas, like Alaska or New Zealand, have extreme tides.  Some, like the Gulf of Mexico and the Mediterranean, have almost none (that's part of why hurricane storm surges are so devastating in the Gulf, their coast is not adapted to sloshing water). 















http://www.hhi.hr/en/projects/viewproject/11


The tides have patterns, and the patterns tend to mostly repeat with the lunar cycles, but they are a complex dance.  The tides don't simply 'wax and wane' like the Moon's light.  The ocean does get pulled by the moon, but it doesn't bulge at full moon and shrink during the new moon.  There's always the same amount of water, and it returns roughly to its own level one way or another. 
You can have big influences due to current weather (storm tides), undersea earthquakes, or big ice-sheet or land slides even.  "Tidal waves" are more often called "tsunami" now by scientists: these are seismic-driven waves due to earthquakes, volcanic eruptions, or big land-slides, with no tidal influence involved.  However, tsunami are big and broad, and they drop and flood into harbors like a very fast and extreme tide, rather than being a surface-level curling wave like wind-driven fetch.  Storm waves batter and froth; "tidal waves" can funnel into certain harbors like a tidal bore, as if the ocean had changed its mind about where to allow a shoreline.

The tides are wild and mysterious, and hard to predict without a chart.  Those charts are based on years and years of experience, records going back centuries for many ports.  But once you are tuned into your local tides, you may be able to use your own observations to take a guess at the current tide based on the time of day and phase of the moon.   I feel pretty good if I can get within an hour or two this way - that's close enough to schedule a harvesting trip or keep me out of trouble on a coastal hike.  The tide charts are way more reliable, but it's worth trying to learn the local patterns if you're interested, in case you are ever caught without a current chart.

If the tides don't line up from one coast to another, I don't imagine that all plants will respond the same way to the "lunar pull" across continents and climate zones.  Or for that matter, that they would respond more strongly to "lunar pull" than to the sun's stronger pull, or the Earth's even stronger gravitational pull.  If I had to guess, I would imagine that the plant feels a very slight fluctuation in the earth's effective gravity.
 If you're just talking about upward 'pull,' the sun has 175 times more pull than the moon.  And they are both pulling on us at all times, sometimes up and sometimes down.  It's just relatively the same across all the earth.  The daily small difference in pull, as our side of the Earth turns toward or away from the sun, is about 44% as much as the moon's difference in pull.
http://hyperphysics.phy-astr.gsu.edu/hbase/tide.html.


The strongest pull would be when the moon is closest, and when it's lined up near or exactly opposite the sun, at the same time: 'supermoons'.  https://en.wikipedia.org/wiki/Supermoon

Factors like temperature have a much more measurable effect on plant growth (and insect and fish maturation - to the point where hatcheries and stream volunteers talk about "degree-days" to maturity).  Weather affects temperature.  Some animals definitely can feel and respond to barometric pressure, as do some types of plants (Ernie has a "weather leg" that pains him with pressure changes, and he recalls some type of orchid that opens and closes with changes in the barometric pressure).

Some flowers called "moonflowers" are just round and white; a few of these (and others) bloom mainly at night.  A very few are said to bloom mainly during the full moon.  However, there's a good argument to be made that this behavior could evolve to attract specialized night-flying pollinators, like the more common night-blooming behavior.  Some pollinators may be particularly active or accurate in finding the flowers with more moonlight.  The idea that it's moonlight, rather than some kind of gravitational pull, that sets the cues for this dance would be reinforced if the plants could be mis-cued by artificial light, or by variations in day length.  There are a handful of such species I found mentioned online (on a less-than-impressive eHow post , or the more ordinary evening- and night-blooming flowers listed here on Ava's Flowers http://blog.avasflowers.net/flowers-that-bloom-in-the-moonlight).  All three of those said to bloom best in the full moon (datura inoxia, one of several plants commonly called "moonflower;" night-blooming jasmine or cestrum nocturnum, and night scented stock (Matthiola longipetala) are tropical or subtropical plants, which prefer roughly 6- to-12-hour days with warm or hot temperatures.  The last one is a desert plant blooming mainly in spring and fall (12-hour days).

I'm impressed by serious gardeners in any case - and these plants appear to have a lot of strict requirements besides the lavishly regular lunar cycle. 

However, one thing that excellent gardeners often share, and I fall short, is a reliable sense of time and time management.  If gardeners sometimes build mystical stories around their all-important calendar or almanac, a little poetry to get the juices flowing and help you stick to your plan, there's nothing wrong with that (unless it makes you less open to reliable, proven methods that might be of more help).  So if a lunar planting, weeding, sprouting, and rooting cycle is working for you, keep doing it. 

 Lunar cycles are a good predictor of changes in animal activity levels (including humans), possibly due to availability of nocturnal light and enhanced twilight.  This light/activity connection, which also affects a LOT of nocturnal pollinators, could be one reason why some very successful gardening methods and guides have used the moon.  Full moons have been used historically for extended work hours during harvest, and for festivals where participants might travel and celebrate longer together without fear of being caught in the dark o the way home.

Many gardeners are women, or live with women; our menstrual cycles famously synchronize with the moon.  It is worth tracking our own cycles. Any given woman may feel more productive in certain lunar phases than others - though I would expect this to vary person to person.
I have had some difficult years when somehow EVERY heavy-lifting workshop and over half our air-travel dates managed to line up with the wrong "time of the month."
While some ancient cultures put taboos on menstruating women participating in certain activities (cooking, handling sacred items, etc), these may be related to harmonious concentration, intense arguments, or the possibility of blood stains attracting scavengers.  In the modern context, menstruation cycles can usually be managed, they're just an extra burden to bear while working on a time-sensitive project.

However, there's one more reason why lunar cycles might be a popular element in garden planning guides and almanacs.
The moon has strong mythological connotations, and has been part of both calendars and legends for longer than we can remember.  It's attractive; it's sexy; it's mysterious; it's a little risque.  And in the world of marketing, sex sells.  A calendar that marks out the full moon, or gives poetic lunar instructions for getting through the tasks of the week, might simply be more interesting.

I'd rather take my poetry at full throttle, with moon and flowers fleshed out in beauty, scents, strong feelings, and layered symbolism reflecting my human needs and longings.  And I'd rather let my science explanations stand or fall on their own merits, humble as science should be, proven or disproven by results over time.

If the moonflower likes moonlight best, so be it.  If it's happy with a 12-hour daylight cycle, a little evening coolth, and maybe a grow-light boost when I want to party out of season, then we can have fun together that way too.

And if planting your seeds on Monday and Tuesday this week, but not until Thursday or Friday of next week, works for you, then do it.

I find that my seeds get planted "now" or not at all.  There are enough challenges in semi-arid gardening while working out-of-town gigs; I don't need a mystical schedule to tell me I'm doing it wrong.
From what I've seen, plants grow very well for people who pay attention to their individual needs and their common routines (like water, temperature, sun and shade).  They can also grow well for people who believe in all kinds of moons and fairies, as long as they also get out in the garden regularly and give the plans good physical care.

But for those who, like me, are juggling too many interests and obligations to regularize our garden time, there's a risk that a demanding garden schedule could become an excuse not to plant anything at all.

If you don't have any of those challenges, and you see some difference between Tuesday's and Thursday's plants despite perfect control of water and temperature, then you have the luxury of refining your methods on your own terms.  I have had a few personal experiences with "talking to plants," or more specifically asking permission and listening for an answer, that take the edge off my skepticism about this whole sort of thing.  But I'm still 

I'm a sailor in training, and an incurable science geek.  Being 'in tune with nature' feels good in any case, but it matters even more if you're surfing the tides in and out of harbors, and trying to keep track of wind and current effects on your course.  Sailors can get pretty picky about the accuracy of their nature-based information.

I've been learning boatloads of this stuff lately.  It's amazing.

Yours,
Erica W