Desert Heat

115 Degrees Fahrenheit. In the shade. On the East side of the house. At 5:00 PM CST

One could say that is is just a little warm today here in the Mojave Desert on June 21st.  This is day three of temperatures over 112 for us here in Sunset Zone 9a in Fabulous Las Vegas.  We are on the East side of town but low enough at the base of the foothills that it's not the coolest part of town. That would be up on the slopes of Mount Charleston, where it seldom exceeds 95.  But there are warmer spots such as down in Laughlin, NV where it got up to 120 yesterday. 

So, what does a gardener do when it's this hot? Try to keep perennials as comfortable as you can.  That means three things: mulch, shade and water.  Mulch we've already taken care of as mentioned in previous posts.  We've supplemented it a bit with the stems of 'bonus plants' which have either ended their annual life cycle already and/or succumbed to the heat. 

Dead 'bonus plants', dormant Bermuda grass (also bonus) and wood chips insulate the soil here.

 

 

 

 

 

 

In the case of this West facing car port, all we can do really is try to insulate the creeping acacia with mulch and try to keep a few standing 'bonus plants'. 

Tree and shrub branches under cloths keep these shelves shady.

We've also amped up the shade with trimmed limbs and cloth on the shelves along the East wall. As well as moving more shelves over there to help get more of the plants into afternoon shade.  The big elm tree helps (and the tree itself is doing well thanks to the soaker hoses) shade the plants for part of the afternoon, but unfortunately, the setting sun gets under it in late afternoon. 


Our new catclaw acacia will someday be able to handle the heat fine on its own, but it's still a little sapling, so we are trying to help it out with extra afternoon shade......

This old lawn chair is just right for PM shade for our little catclaw acacia.

......courtesy of an old lawn chair that I keep around even though I probably should get rid of it.  I'm glad I kept it this year as it's fairly tightly woven mesh back is just right to give this little catclaw acacia some afternoon shade when the heat is the worst. 

Then, there is water.  It's tricky to deal with in this heat as you don't want to over-water anything and drown the roots. On the other hand, plants evapotranspirate (a combination of purely physics based evaporation along with plant energy requiring transport of water from roots to the rest of the plant)  and use water to cool themselves more than what they actually use to grow. This is especially the case when it is so hot outside. It's one thing for a plant to keep its cells cool while they grow, respire and (in some cases) carry out photosynthesis - all of which produce heat in the plant.  It's quite another when the air outside the plant is even warmer than the plant's normal temperature. 

When that happens, most plants will take up more water than usual as long as it isn't too hot.  When it gets above 80, most plant processes begin to slow down and growth usually stops.  Almost all plant processes stop when it gets well above 100.  Then the plant enters a sort of dormancy state but it is not as dormant as some plants get when it is too cold in the winter and still needs water and other nutrients.  Then, when it cools off at night (even as hot as its been here, it gets down to the high 70's - low 80's at night this time of year), the plant will resume growth and most other processes.  I've observed the most growth on closely monitored plants in the morning after a cool (or at least somewhat cooler) night.  

Even 'drought tolerant' and desert native plants behave this way to a greater or lesser degree. It's part of what makes them able to live in such hot places as they are better at shutting down and insulating their stems and leaves from outside heat than plants from wetter, cooler places are.  So, we increase our watering times from the once a day schedule in late Spring (the weather, never what the calendar says) to two times a day (early morning and early evening - never water in the middle of the night as that's a ticket to fungal problems) in June to ever six hours or so during the day when it is above 110. 

We can do this without over-watering the plants because we are using soaker hoses which put out about 1/4 a gallon of water a minute for every 10 feet of hose under the typical house's hose bib delivery capacity of 30 gallons per minute.  And we run the hoses for 30 minutes each time. That comes to a total of 3 gallons per foot of hose covered area each day.  This is enough, when you estimate losses from evaporation, to get about an inch of water in the top 2 inches of the soil (if the soil drains well) and hopefully, part of an inch soaked down deeper into the soil to encourage a deeper, better root system.  Evaporation is not a total loss though, because it helps cool the soil, plants and the air immediately around the plants. Yes, it is good to try to minimize evaporation, which is part of what mulch and shade do, but some evaporation is necessary, especially when it is this hot.

This clay pot without a drain makes a great evaporation basin.

That's why I encourage evaporation pans like these around plants in dry climates. It helps simulate an environment that you'd have near a stream or pool here in the desert where the more showy plants that we like to have live in nature.  This clay pot in the above picture doesn't have a drain hole. I found it at a thrift store and figured it was a perfect little mini-water storage basin.  Placed under the soaker hose, it catches some of the water and stores it, releasing it by evaporation slowly thanks to how small diameter it is relative to how deep it is.  Plants nearby enjoy a somewhat more humid, cooler microclimate like what they'd have at the edge of a pond. 

This volunteer sunflower wilts each afternoon.

   For some plants, all of this effort isn't quite enough, but some are hanging in there and kinda bouncing back by morning like this volunteer sunflower.  This sunflower is getting some water from a soaker hose, so it does well in the morning and early afternoon, but is rather wilty by evening.  If it survives to bloom, great. If not, I won't be terribly surprised. 

These wildflowers are doing just fine.

Other, more desert adapted or native plants are doing much better like these wildflowers from a mix that I broadcast last fall.  In fact, they didn't bloom until a couple of days ago. 


We'll see how everything turns out once things start cooling down again.  I wish you luck with keeping your plants happy (or at least alive) this summer!    

Rain tests out the new stain job on the wooden wheelchair ramp

Rainwater beads up nicely on this freshly stained wood.

Nothing beats a trial by fire.  Or, in this case, rain.  We thought we did a good job of staining this wooden wheelchair ramp, but a nice little rainstorm early this morning really put it to the test.  The water beaded up and ran off just like it should. 

Even these handrails repelled water well.

We inspected the whole job and found that even the dryest and most weathered wood took the stain well and is repelling water as it now should.  It doesn't rain often in the desert, but when it does, it still does damage to wooden structures so this was worth doing.

Why stain your wooden hardscape? This picture tells the tale.

We had some stain left over after finishing the ramp (better too much material than not enough), so we stained a few other wooden hardscape objects as well.  It makes them all match and they all needed protection just as badly as the ramp did.  The puddles on this raised garden bed tell the tale of why staining wood outdoors is worthwhile. 

But how does water repellant wood stain work? I mean, it's liquid itself right? It soaks into the wood, especially this weathered wood, really well.  It didn't form a plastic like coating on the surface of the wood. Other than being a little darker, it looks and feels the same as before.  But now the rain water isn't soaking in.  I did some research.

The first thing I found out was that the stain we chose contains linseed oil. The oil fills the pores in the wood so that water cannot enter them.  It, like all oils, is naturally water repellant.  Everything is made from atoms which are incredibly tiny, electrically charged particles made up of negative electrons, positive protons and neutral neutrons and those atoms are combined to form molecules.  Some molecules are fundamentally stable enough to be considered elements, such as the oxygen and hydrogen that make up water. The hydrogen bonds that hold water molecules together are such that they leave some electrons still free to attract to other positively charged molecules, such as those that make up cotton fibers (which is why cotton clothes soak up water like a sponge).

Oil on the other hand, is made of chains of molecules that are bound together in ways that there aren't nearly as many electrons free to bond with other things, making a liquid oil nearly neutral in charge, thus the negatively charged water isn't attracted to it.  It get's quite complex, but that's about the most simple way to explain it. 

A great picture of the flax plant and its products by Handwerker on Wikimedia Commons.com

Water molecules. Note the positive charge of the hydrogen (H) is attracted to the negative charge of the oxygen (O)

A simple oil molecule. Hydrogen (H) electrons have filled all the available bonds with protons in the carbon (C) atoms, thus no space for the available electrons on the oxygen atoms of water to be attracted.

The stain we used also has what they call WaterGuard water repellants, which are trademarked and not disclosed, but are likely to be man-made polymers that are a lot like natural oils and that enhance the properties of the linseed oil. 


In addition to the raised bed, we also stained this wooden fence protecting a little patio area.

Water is running off this wooden fence now.

Stained this shade awning for the water system

And this shade awning.  Shade awnings like this are essential for protecting hoses, pipes, etc. of water systems for homes in the desert. Otherwise, the UV light from the sun will weaken the rubber and plastic they are made from. The awning also reduces the amount that the water gets heated during the summer so that water won't be so warm when it comes from the tap in the sinks.

Staining wood isn't terribly fun as it's difficult to keep the stain from getting on places where you don't want it and it's a sticky mess to get off your hands (rubbing alcohol on an old rag works about as well as anything), but it is important for having a sustainable landscape.  Being sustainable and environmentally friendly includes preventing materials in the landscape from becomming so damaged that they have to be thrown away and replaced.  By protecting these wooden structures, we're avoiding adding damaged wood to the landfill (or even the effort, time and money involved in getting it recycled before its useful life is truly over) and avoiding having to contribute to the demand for new lumber (and all the enviromental costs involved there), at least for the time being.  

Saving a wooden wheelchair ramp from an early demise.

This wooden wheelchair ramp is only about 6 years old.

Wood is a great mateial to build things with and has been since the dawn of human civilization.  It's one of the lightest yet strongest materials to work with; most flexible in terms of what you can build with it; easiest to work with without expensive tools and one of the most pleasing to the eye in a landscape.  However, it does have it's downside: it does'nt last as long as some other materials do, especially if it is not properly protected. 

This wooden wheelchair ramp is only about 6 or 7 years old, yet it looks much older.  It is still strucurally sound for the most part, but is showing signs of beginning to fall apart already. 

Wood on this handrail is seriously warped & is coming loose.

The wood was stained back when it was built, but they must have used a very low quality stain that lacked good UV and water protection.  In places, it is as grey as an old barn. Worse yet, it is really drying out in our hot, dry climate and is starting to splinter apart.  The handrail above will be unsafe to use soon if something isn't done. 

Wood rot on this siding.

The lower sides of the ramp are covered with wooden siding which is working well for the most part, but in the places where they piled dirt and crushed rock against it, it is starting to rot.  We dug the rocks back from it and will keep them away.  We don't get a lot of rain in Las Vegas, but enough to cause wood rot if the wood isn't allowed to dry out fast enough. 

Some sort of borer larva, possibly Flathead Borers, have been munching on this post.

This post shows signs of some species of wood borers, maybe Flatheads, tunneling in it.  It is still sound so far, but will have to be replaced if the damage gets any worse. We'll be keeping an eye on it now that we know about it.  Haven't seen any signs of damage in the other posts yet. 

We highly recommend looking over all of your wood structures on your property for damage like this.

We dug down as far as we could around posts to get them protected too.

A good quality stain with UV & water protection

We decided to start with a well applied coat of good quality stain first and see if that is enough to deal with the drying wood and hopefully, even retard further borer damage.  We don't endorse any products, so we won't show the brand, but the things to look for are ultraviolet light (UV) protection, water resistance and a moderate price.  Like many things, you get what you pay for and the really cheap stain isn't truly worth your time to use as it doesn't last. 

This project was done in the autumn in Octorber as it's a great time of year in the Desert Southwest to do outdoor hardscape projects.  Cooler weather makes it more pleasant to do physical work like this and the stain will cure better when it is neither too hot nor too cold. 

Before

 

After

Not only is the wood better protected from our harsh climate, it looks much better too. 

Rescued Butterfly Bush Finds A Home

Butterfly Bush Buddleia davidii

This Butterfly Bush (Buddleia davidii) was rescued from the discount rack at a local big box store that we call 'The Orange Store'.  It came in a tiny, flimsy plastic pot barely big enough for the roots, but only cost $2. It was wilty and sad looking at the time, but we saw promise in it because it had the best formed trunk and branches; no obvious evidence of girdling roots and several flower buds. 

When we brought it home, we put it in a spot under a California fan palm sapling (that will be transplanted too someday) and on the East side of the house to protect it from being blasted by the hot, setting sun each afternoon.  We transplanted it into two nested pots filled with a soil-less potting medium high in pearlite to ensure drainage and watered it until water began to drip from the bottom of the pot (it was sitting on a stand so that the water could drain out) every day.  

After it quit wilting, about two weeks later, it started to flower. The flowers sure are pretty! We are looking forward to seeing how it looks when the plant can support full inflorescences of blossoms.

Butterfly bush blossoms

The pink blossoms contrast nicely with the opposite leaves of this plant which are dark green on top (adaxial surface) and covered with fine, silvery white hair-like wax on the bottom (abaxial surface).  It may continue to produce pink blooms, or the next set might be a darker red, even almost purple as these plants have some variety in blossom color.  The flowers are quite small as seen above and are rather simple, yet elegant, in design with one row of petals, each with serrated edges, fused into a tube with a deep center that hides the pistil and stamens. 

Butterflies and hummingbirds possess tongues long enough to access the sweet nectar that these flowers produce.  We hope that this bush will become a natural feeder for them so that we'll get to enjoy watching them flit around the yard.  Since we never spray pesticides in our yard, we think we stand a better than average chance of attracting them now with this bush.


Once the bush flowered for a while (another couple of weeks) and even began growing new leaves (a very hopeful sign that it might survive after all), we decided to transplant it again.  The weather was cooperating too with highs in the 80's forecasted the whole week and a 40% chance of rain.  Cool, rainy weather is ideal for transplanting many species in the desert. 

To give the plant the best chance of success, we carefully planned its new location.  A well placed and well dug hole is the key to success when it comes to transplanting out here.

The ideal spot was between this wall

And this planter

We paced 7 ft from the wall to give the bush room to grow

This is a good spot because it will get morning sun, but afternoon shade from the house and it is close enough to my makeshift drip irrigation set up (someday, I'll install a proper irrigation system) that I can set a drip on it if I'm gone for an extended period.  It is also in a fairly level spot which will make controlling runoff much easier than planting on a slope.

Butterfly bush can grow to be about 15 feet wide and 12 feet tall, so we wanted a location where it would have plenty of room to grow without getting in the way of anything.  As you may have noticed from other blog posts, we are not big fans of needless pruning.  Had we planted this bush closer to the sidewalk or wall, it would need pruned almost annually.  Where it will be, it won't be too close to any of the traffic paths, and may even cast a little shade over the planter box someday. 

 

"Weed Barrier" is in the way!

Weed Barrier is a myth. It doesn't prevent weeds for more than a couple of years after installation.

Fine gravel under the plastic?

When we started digging, we discovered to our dismay, that the previous owners of this property had fallen for the myth that putting a layer of black plastic under your rocks would prevent weeds.  Apparently, they placed it over the entire yard.  We'd already removed some of it around the trees shortly after we moved in.  This plastic is going to have to go away if we can hope for healthy root systems for our plants.  It's preventing gas exchange between the soil and the air and is impeding water infiltration.

Good soil under the rocks

The soil profile of our yard. Note the compacted layer on the surface.

Now that we've gotten the rocks and plastic and compacted soil out of the way (please oh please dear reader, never cover your yard with rocks no matter what your water district says!), we've found actual soil.  We're blessed to have chosen a location in the Las Vegas Valley that has loamy sand soil with fine gravel! This is primo soil for the Mojave Desert. Very good drainage and just barely enough clay and loam in it to help hold moisture and nutrients.  Other places in the valley aren't so lucky and have layers of caliche 'clay' which is actually coral that was pulverized and buried when the volcanoes that are now the Black Mountains to the South erupted, burying what was once a huge lake as big or bigger than the Great Salt Lake to the North of us.  Where I am digging used to be part of the shoreline around that lake and is a bit more like digging in a beach than a lake bottom.  This is perfect for many desert native and adapted plants, including our little Butterfly bush.

I know this soil well, so I know what its physical and chemical properties are.  If I wasn't sure, I'd do a couple of tests before deciding to plop a plant in here.  First, I'd get a little vinegar and drip it in a shallow hole.  If it fizzed a lot, I'd know that the soil was very alkaline and may not be the best material to use for a plant species that is not adapted to the desert (such as roses or violets). Then, I'd dig a small hole down to my planned root zone depth and fill it with water, noting the time that I did so.  I'd come back every 10 minutes or so to check the water depth.  If the hole still had standing water in it after 30 minutes, I'd consider planting somewhere else or build a raised bed if there were no other good locations for the plant.  Never plant anything (other than maybe plants from swamps or marshes) in a place with poor drainage. Your plants will never be healthy there. 


We dug the hole down just as deep as the flower pot was and about four times as wide to be sure to get as much plastic and rock out of the way as possible.

Luckily, the pot happens to be as deep as a spade is tall....

Makes measuring hole depth easy

People used to think that digging a really deep hole was key, but research has found that most trees and shrubs do not grow a really long tap root that winds up being as deep as the tree is tall. Only a very short list of trees actually do that, most of which aren't even grown in the U.S.  Actually, the key to tree stability is lateral roots. A wide fan of lateral roots extending out beyond the drip line of the mature tree canopy is what keeps trees from falling over.  That's why one spade deep is deep enough for this bush, but we made it as wide as we could. Someday, we'll probably come back and dig up even more of the rocks and plastic and move them out of the way as the bush gets bigger. 

Gently tapping the rootball out of the pot...

keeps the roots from being damaged

 

Placing the rootball in the hole, ensuring that potting soil is under and on all sides of it

Since the Butterfly bush was grown in soil-less potting media, we chose to keep that around the roots and to line the inside of the hole with it.  Our soil is pretty good by desert standards, but it's good to keep as much of the original soil around the roots to avoid breaking off any more root hairs (the tiny, almost invisible parts of roots that do all of the water and nutrient uptake) than we have to.  Eventually, the roots will grow out of the potting media and into the native soil, so we made sure to avoid compacting the bottom and sides of the hole, even raking at the surfaces with our fingers to make sure the spade didn't compact the soil too much.  Smooth, firm holes just become underground pots, preventing future root growth.

The native soil was gently placed around and on top of the rootball and gradually sloping away from the trunk, leaving a gap about a finger's width around the trunk to help prevent stem rot.

Bare soil was then covered with wood chip mulch out to what will soon be the dripline

Now that the plant was in the hole, we gently placed native soil around the sides of the potting media pile and over the top of it up to about a finger's width of the trunk.  Then, we covered that with a two to three inch thick layer of wood chip mulch also within a finger's width of the trunk.  That will help reduce the chance of stem rot that sometimes happens when soil and mulch are piled up around the trunk.  The mulch will help keep the soil moist and reduce soil erosion.  We used such a thick layer to help prevent weeds and to keep the mulch in place better than a light scattering would have.  As the bush gets bigger, we will move more rock and plastic away from it and add more mulch in its place. 

We then irrigated the plant with about a gallon of water and will water it about every other day to prevent wilting.  Thanks to the good drainage of this soil, that won't water-log the roots.  In heavier clay soil or in caliche, we would have to wait longer between waterings to avoid drowning the roots.  If the soil was really tight, we would have just built a tall planting box full of potting medium on top of the ground with a reservoir hole filled with gravel underneath it and planted the bush in that.  Once the bush is established, a deep watering once a week will be all it needs, even in summer.   

  Now, if all goes well, no guarantees when it comes to growing things, we'll have a lovely Butterfly bush to enjoy for years to come. 
 

Soak up the water around your property, don't make it run away!

This mulched bed has the start of a rain garden at the toe (or base) of the slope. We'll be planting small cacti and annual flowers into it this fall. This trench slopes towards the middle from both ends rather than towards the street.

Even though we don't get much rain in Southern Nevada, rarely more than two to three inches a year, we still get a lot of runoff and even some flooding when it does happen.  Also, irrigation leaks and activities such as washing your car at home and hand watering can lead to runoff if not done carefully. 

It's impractical and downright silly to demand that people stop using water outside and there is nothing we can do to stop cloud-bursts from dumping rain on us (why anyone would want to, I don't know since rainwater is the best irrigation one could hope for).  But we can make an effort to keep what water we do have on our properties and out of the storm sewers. 

The easiest solution is to reshape the landscape around your property.  You still want the soil to slope away from your buildings, but it can then slope towards the middle of a flower bed or lawn rather than towards the street.  It can usually be done by hand with shovels and maybe a pickaxe if needed.  One can dig a trench or a series of holes around the property. The deeper you dig them, the longer they will last before they need dug out again.  Always be sure to call your utility companies and whoever installed your irrigation system before you dig to make sure you don't wind up digging up a pipe or wiring! Then, slope the soil gently to direct the runoff towards the digging.  The bottom of the hole or trench is then lined with crushed rock to help maintain drainage.  Some people add geotextile fabric below the rock, but I've found it doesn't really help and just gets in the way when you need to re-dig the hole.  You can either fill the whole trench or hole with crushed rock or add layers of coarse sand or fine gravel on top of it. 

To make it even better, you can turn this into a rain garden and plant lovely flowers in and around the trench or hole.  Be sure to only use annuals or biennials (plants that live only two years).  Perennial plants will develop tough root systems that will make it really difficult to re-dig the trench later on. 

Others have done such a great job of diagramming and describing rain gardens in detail that I will leave a link below so that you can go to their page rather than trying to make my own.  Just be sure to ignore any advice on these pages that suggests planting perennial plants, trees and/or shrubs in or near your rain garden.    Low Impact Rain Garden Design Templates

 This article (in .pdf form) from the University of Nevada Reno does a good job of summarizing the many ways one can soak up rain, irrigation and spill water rather than letting it run off.  I couldn't really say it much better myself so I'll recommend it to you. Ways to make water soak into your property

This website is excellent in that it helps explain the difference between two terms that get used interchangeably but mean quite different constructions and that are often confused with rain gardens:  french drains and swales. These are both similar to a rain garden only they actually direct runoff away from the property, but at least slow it down first compared to just a smooth pipe running from a grate or a concrete trench.  This website is done by an association of certified home inspectors so their information is pretty reliable. May as well make your home and business construction pass inspection by design rather than having to re-do it later after it is inspected.  French drain inspections 

Finally, if you are considering installing or repairing the pavement in your driveway or sidewalks, here's a more environmentally friendly option to concrete that will also help keep water on your property rather than letting it run away. It's a vendor neutral article by a non profit organization so it's facts rather than hype.  Permeable Pavement

Not only are these permeable pavers and paving systems good for soaking up water, but they are actually easier to do compared to mixing and pouring concrete.  I've done enough laying of concrete to know that I'd rather not do it if I can help it. :)   

A rain garden can enhance the beauty of your property and help manage runoff at the same time.

Rain gardens can be established with or without a drain to the sewage system.  They are great to install around existing drainage systems to slow and sometimes even intercept the water before it gets to the drain. 

Got Plants That Aren't Quite Ready For The Summer Sun?

Now that Summer is here in Southern Nevada, so is the heat.  My agave out by the West fence were doing pretty well until the temps started spiking up to 110 sometimes even 116.  They were getting some partial shade from the shade slats that I installed (see previous blog posts) but it wasn't enough anymore.  The leaves on my variegated agave, which normally roll up in Summer, were also starting to turn white as were some of the leaves of the hedgehog agave (shown here).  Meanwhile, the agave that are still getting partial shade from an ash tree are doing just fine. 

My solution?  Make shade for the other agave.  These milk crates make nice little pergolas.  Just to make sure, I also put a dish cloth weighted down with a chunk of concrete (we get some good wind here).  We'll see how these agave recover from gettin' too many rays with the heat and low humidity (below 10%) that we have right now.