The year 2018 was very dry here at Destination:Forever Ranch, with a total of only 6.55 inches (166 mm) of precipitation. Normal rainfall is nearly 9 inches (225 mm) per annum, so this figure was about 73% of normal. But more stressful to the plants and animals of the local desert was the distribution of this below-average rainfall, with only 3.45 inches (88 mm) of it occurring between January 1 and September 30, or 53% spread out over 9 months. The remaining 3.1 inches (79 mm) or 45% all fell in the last 3 months, with most of that occurring in the month of October.
Additionally, the last 4 months of 2017 from September 9 to December 31 were dry as well, with zero rainfall, effectively making almost 13 months with those paltry 3.45 inches of rainfall from Sept 9, 2017 to October 2, 2018. A record was set in multiple cities across Arizona, Nevada, and California in terms of a dry streak without measurable rainfall, which at D:FR ended up being 121 days, running from Sept 10, 2017 to January 9, 2018. Similarly large triple-digit rainless day figures prevailed across the region, all of which broke records that had been at about 100-103 days, but were smashed at 120+ days. Despite this being a desert, that level of drought is actually quite severe for a region more accustomed to a better distribution of precipitation, especially with a more generous summer monsoon season than occurred in 2018.
A strong low pressure system comes ashore over southern California and northern Baja, Mexico, bringing 1 to 4 inches of rain to both the coast and interior desert and montane regions of Arizona and elsewhere. The screenshot is from NOAA’s Western Continental U.S. Water Vapor Loop satellite, 8:00 AM MST on Tuesday, January 15, 2019.
Fortunately things did improve after October 2018 arrived, with the passage of Hurricanes Rosa and Sergio, and additional extratropical systems bringing more rain in November and December. As I write on January 17, 2019 the region is experiencing a very significant wet week, with multiple storm systems delivering repeated bouts of rainfall across California, Arizona, and Nevada, which when combined with the last three months is helping significantly to alleviate the drought that gripped us in 2017-2018.
NWS storm total radar map for southern Nevada, NW Arizona, and SE California, Tuesday January 15, 2019.
The National Weather Service in Las Vegas issued this radar map estimating storm total precipitation as of about 1 PM on Tuesday, January 15, 2019. Widespread amounts of 1 to 2 inches fell, although radar is unable to estimate precise amounts farther out than about 50 to 75 miles in such weather due to low cloud tops and radar return interference from the very precipitation it is trying to measure. This explains the “bullseye” look confined to the immediate vicinity of the radar installation near Searchlight, NV, about 40 miles south of Las Vegas itself. But when radar estimates are combined with ground reports and automated weather stations, you get a more accurate picture of what happened, and reports of 2 to 3 inches of rainfall southeast of Las Vegas were common over the span of about 20-24 hours.
One of my small, local water harvesting basins traps a couple hundred gallons of water.
The was a relatively slow-moving Pacific low that took its time coming inland and migrating eastwards. The positioning of the low’s rotational center just south of the international border means that the northeastern quadrant of the low where there is the most uplift and forcing was positioned over western Arizona, including me and my plants. The dynamics of lifting air in this NE quadrant, aided by rising terrain and orographic forcing over mountain ranges, meant fairly efficient rainfall production. D:F Ranch ended up getting 2.1 inches of rain (54 mm) between about 7 PM on Monday, January 14 and 5 PM on Tuesday, January 15, 2019. This one storm wrung out nearly a quarter of my typical annual rainfall average!
Since my area is indeed a desert most of the time, and long droughts do occur even by reduced aridity standards of this region, I have created a series of local water collection basins to trap runoff during storms and percolate it deeply down into the soil. Some of these basins are small, around individual plants, and are designed to capture a few gallons of water for the benefit of the immediate plant they surround. Others are larger and serve the needs of several plants.
Retention basin size is partially determined by the plants they are near, and partly by the presence or absence of a local watercourse. While none of these “watercourses” are actually large, the fact is that some of them do drain water from thousands of square feet, or even several acres, upstream. And since several acres of watershed can release thousands of gallons of runoff during a heavy storm, I make those basins larger in some cases to handle the increased volume.
Since generally most of these basins and drainage watercourses are small, I can easily reroute their flow with a few shovelfuls of dirt piled or removed as the case may be. The point of rerouting the flow is the force the water to meander from pool to pool, giving it time to soak in near each plant, and reducing erosion.
Bigger plants get bigger basins, as I said above. The basin around this Argentine toothpick cactus (Stetsonia coryne) can easily hold 20 to 30 gallons of water, which is enough to give this 12 foot tall plant a thorough drink. Deep soaking of this nature helps the cactus (and the adjacent juniper trees and agaves) develop strong root systems that enable drought resistance and good anchoring in windstorms, even when saturated.
Mixed planting of cactus, agaves, and other succulents. The green, leafy herbaceous plants are wildflower seedlings from seeds I sowed in October 2018, just in advance of the hurricane remnants that arrived that month. This will be very colorful in another 6 to 8 weeks once the flowers start blooming in spring warmth.
Other basins provide runoff for multiple plants grouped together. The batch of plants in the photo above were all planted less than six months ago, mainly in August and September, 2018, at the height of the drought. Obviously it was not raining much at that time, so the basins simply caught the irrigation water I applied instead of rainfall. But when rain does arrive, as it did this day, the basins work equally well. As they are intended to.
Close up of the gathering above. The first flowers of Moroccan toadflax (Linaria maroccana) have started opening in white and magenta, with many more to come. Especially now that it’s really rained good and soaked them completely.
Ferocactus pilosus glows bright pinkish-red when the spines are wet. The dead Agave shrevei in the background flowered in 2017. A single agave pup survives to replace its parent, barely visible among the dead leaves of its mother in the upper left corner.
A tall bright green Euphorbia royleana raises candelabra-like arms amidst a host of barrel cacti, agaves, yuccas, a knobby totem pole cactus, and more. While it is hard to see at a distance, each plant has its own individualized catchment basin to retain irrigation water when I provide it, or rainwater when Mother Nature does the work instead.
Pots containing giant white squill bulbs (Urginea maritima, aka Drimia maritima) occupy my nursery sales area. Golden barrels and various Opuntia species stand in the background.
Now, to address the obvious question that concerns most people when they see photos like these: Isn’t all this water harmful to the cacti? Won’t they die? I get a lot of horrified comments and reactions along these lines whenever I happily post photos like these, from people who have been taught to see this as deadly to succulent plant species.
I understand these reactions, because this does seem counter-intuitive to what you should be doing. And indeed, in a different garden in a different climate with different soil conditions and rainfall patterns, this could indeed easily prove to be fatal in the long run. But my garden isn’t like most gardens….
Here’s the deal: I have done this now for nearly 20 years and generally speaking, the plants are fine if they stand in water for a short while. They are not going to succumb to rot simply because their feet are wet for a few hours or days, not even in chilly winter conditions like January in Arizona. And the benefits of deep soaking and reduced need for supplemental watering in the long dry spells which are the norm in the desert outweigh any occasional rot problems that might surface with certain species.
I won’t deny that there are some plants that can’t tolerate this treatment, and I will also admit that not everything I have done this to has loved me for it. But those are a minority of plants when compared to those that thrive and grow much more quickly from the abundant occasional soaking.
Don’t forget that all of these photos were taken towards the end of a storm that brought over two full inches of rainfall. It wasn’t even done raining yet, as evidenced by the raindrop ripples in the surface of the pooled water. Plus, my soil is decomposed granite with a coarse and fairly porous grain structure that drains very well and percolates water quickly. All of these pools were gone, soaked into the soil, within a few hours of the end of the rainfall. Oxygen returns to the soil nearly immediately – certainly the coarse grains and large air spaces enable this within 24 to 48 hours.
The saturation is strictly temporary, and normal aeration levels return quickly, leaving the plants well watered yet also undamaged by the temporal dousing. So no, in my case, in my garden, in my climate, and with my soils, this is not detrimental. In fact, most of the plants thrive as a result of it.
Of course it is worth a disclaimer to say that if you live in a wetter climate than my average 9 inches of rainfall annually, and want to grow succulents and cacti outdoors in the ground, that making water retention basins like these for them is not necessarily a good idea. But of course common sense would tell us that you treat your plants according to the demands of the climate, not solely upon ideology.
Similarly, if you live in a colder region, making basins and setting plants inside them might be harmful behavior. Ditto that with denser, more clayey soils, or in situations with more shade, or greater organic matter content in the soil. In all of these types of gardening or landscaping scenarios, the conventional wisdom of planting upon slopes or in raised beds, and elevating the stem bases to permit greater drainage and air circulation and prevent decay is obviously the smarter path to follow.
Runoff gathers on the surface of Alamo Road and drains off to the left side in the distance.
If, however, you live in a low, arid, and very hot summer desert zone, you may want to rethink the wisdom of providing such extra drainage and dryness in a place that actually needs all the water it can get. If the climate, soil, and individual species of plant you wish to grow all support planting in shallow basins, and the plants seem happy, then why not? Think outside the basin. Or, rather, maybe think inside it. 😉
This Alamo Road runoff exits the road bed via a drainage channel cut through a berm to the left. From here, it heads to my water harvesting catchment basins, which I have covered in other blog posts.
By the way, there is no reason why your cacti and succulents actually need to be planted in the middle of such a basin, especially not a larger one that might retain water for 12 to 24 hours before it soaks away. In some cases, simply planting the succulents on the edges or around the margins of such basins will still yield the same benefits since the plants can readily send roots laterally underneath the soil surface to draw upon the damp soil left behind, without having the crowns or bases actually sitting in water for any length of time. Be flexible, that works too.
The rain is abating and flow is reduced in the Alamo Road drainage cutout, but most of the water made it to my flood basins another hundred yards downstream from here.
It is very worth mentioning here that this flood basin treatment applies to just about every other type of desert plant you can think of to some extent. Many trees and shrubs actually love growing in a basin which receives periodic inundation, whether they are desert or oasis species. Many perennials also do fine, palms generally either appreciate or outright require it, and annuals in season often thrive in basins too. (See wildflower seedlings earlier in the post, above.)
Perhaps only bulbs with a strong dormancy requirement might not be best off in the middle of a retention basin that floods, although I have a few in some places that seem to be doing fine. If in doubt, then either do a test patch for a few years to see if they respond well or not, or simply put them on the margins or elsewhere altogether. There are few hard rules here; it is okay to do what actually works and avoid that which doesn’t, and experimenting is how we learn in any case.
The aforementioned flood basin, filled to about 3 feet deep with what I estimate to be at least 35,000 to 40,000 gallons of water. This water is designed to recharge the aquifer for the nearby well, and sometimes it pools here for long periods before soaking into the ground. That would mean total submersion of any cacti (or other plants) in muddy water for days or even weeks, which obviously would be fatal. Therefore common sense would dictate that a large basin that floods for that long would NOT be the place to experiment. But I assume that readers can figure this out for themselves. 🙂
Palmer agave (Agave palmeri) with water droplets, as a shaft of last-moment sun plays across the distant hillside opposite D:F Ranch.
Towards evening the sun broke through the cloud deck that had dominated and dropped rain all day. After all, what is a day in Arizona if it doesn’t have at least a moment of sun to remind us of why we live here?
The desert ecosystem is shaped by both the presence of water and its absence. Now that the landscape and all my outdoor plants have received a good soaking, most of the plants can undergo a beneficial cycle of growth and/or reproduction. This third week of 2019 has brought me a total of over 2.5 inches of rain (there was another storm earlier, and yet another one will be arriving a day or so after I do this writing, all of which are depositing rainfall) and this is more than enough to permit life to conduct its critical functions for however long. Until the drought returns…. which here, it always does.
The Urginea bulbs and nursery plants a few hours after the other photo was taken, with golden sunset illumination.
As the storm clears, tatters of fog hang over the summit of the hill to my south. The sun has already dropped below Archway Ridge, but it lights up the fog in bright white.
Closer-up view of the fog brushing the rugged ridge and hilltop, with a few Ferocactus acanthodes barrel cactus and Nolina bigelovii flower spikes from two years ago standing on the slopes between the rocks.
Aloe “Hercules” bejeweled with raindrops as the wettest storm we’ve had here in a couple of years departs to the east, hopefully bringing beneficial rainfall to other drought-stricken regions of Arizona, New Mexico, Utah, and Colorado.