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Posts Tagged ‘irrigation’

I’ve had a few conversations recently that revealed to me what a dumb thing it is to call a plant “drought tolerant”.  Wikipedia gets this right technically, but leaves us without enough to apply the information: “Drought tolerance refers to the degree to which a plant is adapted to arid or drought conditions.”

Well, okay – so when we say a plant is drought tolerant, what the heck does that mean?  It means that plant has some degree of adaptability to drought.  But here’s the thing – how much adaptability?  How do I use this information?  What does this plant do in response?

2014 mid march 040

Iris douglasiana

Saying a plant is “drought tolerant” is like saying there is a temperature outside.  Is it cold, warm or hot?   See what I am getting at?  “drought tolerant” only means that there is some degree to which the plant may tolerate (not die immediately) a shortage of water.

More information is needed: enter WUCOLS.  I won’t bore you with the details and technical stuff behind WUCOLS, they do well enough – read through their website.  Not bored yet?  Good!  Now read through the rules on WELO, the California ordinance for water efficiency in the landscape.  Bet you’re bored now.

The deal is that these classifications in WUCOLS mean something.  They quantify how much water a plant wants in a particular region of California.  This does not take into account sun/shade exposure, sun orientation, wind, soil type, or any of the other factors involved in meeting a plant’s water needs.  It is not a perfect tool, but it is the best thing we have going.  WUCOLS isn’t the only resource, you can get information from nurseries and books also, but it is the most helpful hydrozoning tool I use.

In WUCOLS, the classifications are “very low”, “low”, “moderate”, “high”, or it may say “inappropriate” or “unknown”.  This is pretty self-explanatory, but what is most interesting here is that ETo is a reference point – a baseline of sorts.  So a “high” water use classification means 70-90% of the water needed to keep a 4″ tall cool season turf VERY well watered and super lush, or to put it another way, the “high” water classification is 70-90% of a whole lot of water.

I indulged online – I pulled up an article on “drought tolerant” plants from Sunset magazine.  Of their 12 plants in my home town of Oakland, one was classified by WUCOLS as “very low”, one was “moderate”, and the rest were “low”.  Nassella tenuissima / Mexican Feathergrass is listed as an invasive plant by PlantRight and should not be used at all, but WUCOLS isn’t about invasiveness, it is about water, so shame on Sunset!

It is bad juju to mix water use classifications.  If you absolutely must, then the classifications should be next door neighbors – so “low” and “moderate” is kinda okay (provided you irrigate at the higher amount), but “moderate” and “very low” is no bueno.

Next I went to the “drought tolerant” poster child:  succulents.  Low water use, right?  Drought tolerant?!  erm…. no.  Again, WUCOLS demonstrates my point.  In the plants WUCOLS lists as succulents, the same 3 classifications are included – very low, low, and moderate (screen shot is just of the alphabetical early birds, I didn’t pick favorites here).  So much for that assumption.

succulents wucols

So really, drought tolerant is anything that will grow with less than 70% of a boatload of water.  That could still an incredible amount of water, folks.  Granted, the lower classifications are pretty good and some plants truly do have a relatively dry footprint, but all plants need extra water during their establishment period, that is a post for another day.

Oh – and about those drought tolerance adaptations emphasized in the first paragraph:  a drought tolerant plant might go dormant, drop all or some of its leaves, wilt, or shrink in size in times of stress (the drought they’re tolerating) as a way of coping …. and if not watered in time, drought tolerant plants die.  Tolerance is about not being dead yet – it has nothing to do with living well, being healthy, or looking good, it is about living to drink another day.

Thanks for listening!

J

 

 

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You’ve heard that you should water trees deeply and infrequently, right?  I take that approach a bit further and use it for everything – trees, perennials, roses, everything.  I’m careful with my water anyway having grown up in Los Angeles during the 70’s drought when we let our yellows mellow, removed or reduced lawns, and collected shower water.

See, we’re in for some serious growing pains while we struggle to understand and adjust to mandatory water restrictions now in 2015 – I don’t need to repeat the advice, you already know it (ditch the lawn, add compost and mulch, etc).  But what we need to be doing is more than just using less water, we need to use water more wisely – to help our plants fend for themselves better.  I see water as a training tool and my plants as smart, but slow.  They can’t fetch and training them to do much of anything takes years.

As of my last water bill, I’m down to 36 GPD (gallons per day) including landscaping.  Before you bow in awe to this amazing feat, you should know that I irrigate my garden a little differently than most and I’m not watering anything I don’t want to keep.  Let the rest die, they’re out of here anyway.  april 2014 Magnolia installedHere’s where I water differently:  I bought a 15 gal. Magnolia ‘Black Tulip’ (that baby green tree in the background left-side).  It is rated as having “moderate” water needs in Oakland by WUCOLS.  Moderate isn’t exactly water-wise, but I’ve got a theory…..  and so far, so good.  I planted the tree a year ago this month.  At the same exact time, my client in Mill Valley had three planted (guess whose idea that was).  Their landscape contractor did exactly what they usually do – they amended, fertilized, and watered the hell out of those trees.  My client’s trees bloomed and grew and leafed out beautifully, gained stature nicely.  Mine didn’t.  Luckily for them, theirs are next to a lawn that I’m sure they’ll keep as long as they can, where I have no lawn.  Below is a better shot of mine last May (1 month after planting).

may 2014 MagnoliaI planted mine with a bit of compost, watered it in well that first day, and walked away.  It looked fine for a while, then it got all stressed out and started dropping leaves.  I watered it again, a nice soaking, and it threw out some new leaves.  We did this all summer:  I kept an eye on it, watering only when I found signs of stress in the leaves, but then not again until I saw more stress.  It was nerve-wracking.  The tree did not visibly thrive, and it sure as heck didn’t get much bigger.  I’m pretty sure it would slap me if it could…. but it survived.  While it was dormant over winter and I held my breath to see how it would do come spring.  This spring when it started blooming, I was delighted with how many (albeit smallish) flowers there were on my young tree, and now it is leafed-out for the season.   I’ll be doing the same this summer, soaking the presumably larger root-zone, but as seldom as possible.  I’ll also be adding more compost on top (not working it in, that’s the worms’ job) and maintaining a good layer of mulch over that.

I believe that what I am doing will be better for my tree’s long-term durability.  I believe that I gave it reason to throw energy into its root system in search of water, and that I rewarded deep root growth instead of fast, exciting foliage and gains in stature.  Over the winter, its root system likely continued to dive and while I watered, soaking further and further down but less and less often, we’re working together to train this “moderate” water needs tree to survive more like a drought tolerant tree.   Here it is today, not much bigger, but doing just fine:

150413 magnolia tree 015I don’t water fast enough that it trickles off, doing by hand what irrigation designers call “cycle and soak”, making sure that the water goes into the soil and nowhere else.  I’m also taking advantage of the few light rains we had to water further than the rain itself went = deep watering every time.

I can’t tell others to do this, the tree looked like hell that first year of establishment and I think most people wouldn’t watch closely enough nor would they enjoy the experience (even I was a bit nervous).  We’ll see how things go this summer, but I can tell you that I don’t water much, maybe once a month?  I avoid watering if it is overcast or cool outside.  I look closely at my plants in the most stressful times – when it is blazing hot, sunny, and/or dry and windy.  If I see stress, I’ll water.  If not, forget it.  I’ll keep you posted on how things go this summer.

150413 roses and MagnoliaThe most impressive thing, though, is what I noticed in putting together this post – look how much my roses LOVE this treatment – they get watered only when the tree gets watered and I have yet to see them look even a little stressed.  You can see the change best between the second photo and the one above.  They’re the hybrid tea ‘Stainless Steel’ (my favorite).  Here’s the original one (now on the right in the photo above) blooming in my old garden in Alameda in 2010 and again in 2012:rose 'stainless steel' jun 2010Rose 'Stainless Steel' full on 2012

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I am sorry to say that despite the incredible amount of coverage that water use gets these days, almost none discusses some of the long-term effects of inappropriate watering practices.  I am not going to start counting how many gallons you can save by switching to drip irrigation, or the fact that spray irrigation can lose 50% to the wind and evaporation before your plants get any of it….nope, I’m not.  I do want to mention a few things that I’ve learned through being a Landscape Architect and a gardening enthusiast:

Roots: I read a letter to the editor in our glorious Alameda Journal (23 october 2009) in which a woman complains about street tree roots buckling her walkway.  I have not seen her property, but I would bet a whole lot of donuts that the problem can be traced back to shallow irrigation.   Roots know what they’re doing, they take up water and nutrients for the plant (tree, shrub, whatever).  They will go where the water is, and if the good stuff is to be found in the top layer of the soil, that is where you will find the roots.  This goes for a tree, a shrub, all plants including a lawn.  So when your sprinkler system is on for 10 minutes and soaks in maybe 3″, or you stand outside with a hose for half an hour, you can expect the majority of roots to gravitate to that topmost layer, including those of walkway-bucking trees.

Here’s the part I wish those water-wise articles would mention:  IF you water your plants deeply and less frequently, their root systems learn to dive deep to find it.  Even a lawn can have roots that are a couple of feet deep!  Water deeply, and the water lasts longer, is available to the roots of your plants, and then when there is a drought, those plants have a better survival rate thanks to their deep, probing root structure!!

Containers: I prefer terracotta pots for the numerous ways in which they have been a good home to my plants over time (oh yeah, this is about water, not pots… I’m getting back on track now).  Whatever containers you use, when the root ball dries out, it shrinks and pulls away from the sides.  The next time water is poured into that container, the water runs around the rootball (not through) and out the bottom, doing the roots of your plants no good.  There are goofy weird products on the market that claim to hold moisture in the soil, or add water over time, blah blah.  I’ve tried many and never liked one.  In my garden, I have a 1/8″ thick wire stake of forgotten origin that I use to poke holes into the rootballs of neglected container plants when I water.  The holes allow air to escape, water to penetrate, and roots to get what they need.  If I have been particularly rotten to my container plants, I fill a bucket or my wheelbarrow with water and I soak them in it to allow them to really soak it up.  A note:  I don’t think self-watering containers work well.  The photo below shows a lovely display from the Los Angeles Getty Museum gardens several years ago – I wonder, though, are they hand-watered?  is the water allowed to drain out?  Was I just lucky enough to see this display before that water stained the paving?  Container plants need water and drainage in order to stay nice for more than a short time.

succulents at the Getty

Watering Practices:  I love walking around in the evening, winding down after my day.  I see a lot of irrigation at night, though, and wish that more people understood the benefits of watering in the early am instead.  Plants lose most of their moisture during the heat of the day as a byproduct of photosynthesis (evapotranspiration from photosynthesis is where plant-released oxygen comes from), so watering before plants need it is ideal (but if you have wilting, dry plants at noon, they need it asap!).  If you have good drainage, so much the better because the (assuming we’re not growing aquatic plants) roots won’t be left to wallow in suffocating muck.  Leaving plant roots in cool, damp soil as the temperature drops (evening watering) can promote the growth of undesirable mold, fungus, and plant disease.  Please also pay attention to the drainage of your soils!  The water here is pooling due to being both trapped by the edging and also because the soil in this area is so over watered, it has developed a scummy skin that keeps their irrigation efforts on the surface for hours after each watering.

Please know that there are evapotranspiration (ET) irrigation systems that can adjust automatically (with the help of a weather station) to turn the water off when it is raining, adjust for seasons, soils, slopes, and planting types!  You do NOT have to rely on remembering to run out in the rain to turn the thing off or waiting for your maintenance service to do it for you.

bad drainage suffocating muck

Runoff: Okay, so we’ve talked about water and your vegetation, and we know that we don’t want to water the sidewalk, but what about all that flooding that we get in a good storm?  Permeable paving products hope to help solve the problem, see this report adopted by the California Coastal Commission in March, 2007.  I would point out, however, that permeable paving solutions are dependent on proper maintenance, and that even compacted soil can resist water penetration as well as any hard paving material.  So, not to get into a discussion of style or design, I would encourage everyone to consider where a permeable solution can be used.  It is far nicer to have all that lovely rainwater seep into the soil than to run off our urban and suburban surfaces, filling up the storm drains instead.  I was given this book on Rain Gardens as a gift about a year ago, it is worth reading.  I bring up runoff, because I’ve noticed several water-saving lists recommending adding non-planted areas to cut down on the amount of water needed to irrigate.  I think that suggesting this is misleading and not necessarily an environmentally friendly practice.

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I admit, this post is not exactly exciting.   It is important, though.  All property owners should understand at least the basic concepts of landscape water use.  The issues are multiple and varied and it is not reasonable to expect that I can smoosh it all into one thrilling, must-read post.  I am sorry to see (I’ve been online for several hours at a time over a few days) that though there are TONS of websites with water saving tips, few address the multitude of issues very well.

Guess what?!  In January 2010, California will require certain landscapes to be more water efficient.  The state adopted ordinance AB 1881 in March and it will go into effect January 2010.  Unless the governing city or county where your project is has already adopted stricter ordinances regarding water use, AB 1881 is the new rule.  As of November 2009, I have not found anything in the city of Alameda or Alameda county websites that restricts water use more than AB 1881, so I am assuming for now that it is our new rule, too.

Suzanne Palmer of David Neault Associates in Temecula wrote a post back in February that outlines the history of California’s water problems and discusses both the genesis and some of the aspects of AB 1881 – no need to re-invent that wheel, she covered the issue well.

Emily Green, a columnist for the LA Times posted a bullet point list on ordinance AB 1881.  Her list does an excellent job of illustrating which projects that will be affected by this ordinance, including private residences.

WUCOLS:  A Guide to Estimating Irrigation Water Needs of Landscape Plantings in California.  This publication is industry standard.

The Save Our Water website is a statewide public education site with lots of fun links, tips, calculators, etc for both indoor and outdoor water use including kid-friendly challenges.  Of course, there is also the Bay Friendly site that covers a variety of Bay Area specific environmental topics.

Residents of the East Bay who are customers of EBMUD may benefit greatly from their Residential Landscape Rebate Program.   EBMUD also published a book a few years ago that I have and love.  The book illustrates better than any others I’ve seen that a water-wise landscape doesn’t have to look like a cactus garden.  I like cactus gardens as much as the next guy, but I do feel that the word “xeriscape” earned a bad reputation and misunderstanding from too many gardens looking alike.  Using water smart practices and appropriate plants does not necessarily dictate the style of a garden! EBMUD also has a WaterSmart Center on their website with links to rebate programs, free stuff, and even free on-site water use surveys.

I encourage all my clients to invest in a self-adjusting irrigation controller.  It doesn’t cost much, can work with an existing irrigation system (we’re just talking about the controller and a weather station, here) and usually does a better job than your gardener will.  That brings me to this evapotranspiration web page and the benefits of self-adjusting irrigation controllers from Urban Farmer.  At the top is a link to a comparison chart for the top five brands.  Urban Farmer is absolutely the go-to place for irrigation products, all the contractors I know get their supplies (and tech. support) there.

If you have read anything online, or watched the news, or read a paper in the last decade, you already know that water use and conservation is an issue in our state.  Things that can save water include:

  • mulching
  • grouping plants into water-use zones, and using drought tolerant plants that are adapted to your area
  • switching from a typical sprinkler system to drip irrigation or sub-grade irrigation
  • Watering in the early am (not late at night, please!!!  that actually promotes pathogens) so the plants can take up the water in time for the warm day ahead.
  • cleaning sidewalks and driveways with a broom instead of a hose (well, duh)
  • adjust your irrigation system so there is no over spray onto paved surfaces
  • look for leaks in your watering system, pool, spa, etc and watch your water bill for changes
  • replacing lawn with water-wise plants

Above, I think I’ve compiled a decent overview of the basic water issue, but I am still bugged by the correlating issues not mentioned.  Please stay tuned for a future post focusing on these corresponding not-so-often discussed side-issues.  They’re just as important for the sustainability and long term success of any landscape.

Thanks!

drought tolerant grasses and perennials

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