Today, I’d like to talk about a subject that is on the mind of every gardener… water. It’s especially true for the brave and adventurous souls who garden in hot and dry climate areas.
This is such an important topic here in the desert and one that needs to be given the attention it deserves. To that point, I started working on this blog post over two weeks go. I thought long and hard about how I wanted to approach this subject in order to give you concise, thorough and easy to understand information that you could take away and use in your own garden.
A lot of people would approach this topic by providing information on how they water their veggie plants… the formula that best serves their garden. I wanted to do more than that. To give you information that was more practical and usable than simply an explanation of what I do. Something that you can easily translate in your garden. But, in order to do that, it required a bit more reflection on the subject. Especially since I am a firm believer that an effective watering plan requires more than just the water schedule component of the plan.
So how does a water-conscious gardener answer the question, “how much and how often should I water my garden?”
When I first moved to Las Vegas, Nevada from Southern California about eleven years ago, I was convinced my gardening days were over and my only growing options were either rocks, cactus, more cactus, mesquite, palo verde or palm trees. Well, after a lot of doubt, trial and error and LOTS of research, I gladly discovered I was absolutely and completely wrong.
For those of you who live in the Las Vegas area, I’m sure like me, you’ve encountered a number of opinions on the subject of watering a veggie garden. Even when discussing this topic with so-called local experts (i.e., plant nurseries, long-time gardeners, etc.). In my experience, most of the answers given are quite vague, confusing and incomplete.
Here’s just a few of the responses I received…
- Keep the soil moist
- Use a small stick placed against your skin to see how moist the soil is
- Water frequently
- Water deeply
- Water several times each week
- And my favorite… grow cactus
Pretty vague, right?
I’ve gotta give it to them…these are certainly answers, but like I said, they are all quite vague, confusing and incomplete. Worse yet, these simple answers make huge assumptions as to the knowledge and understanding of the person asking the questions. Especially, for someone who is new to gardening here in the desert. In my opinion, an absolutely horrible approach to an answer.
At times, it can feel like the real answer is top-secret only intended for a select few. This can be especially confusing and discouraging for those just starting to garden in our desert environment. So, upon receiving these vague answers, most folks will fall back on what they know about gardening, which is usually based on a location much different from our harsh climate. All the while, they continue to seek out a real-world answer to their question. Some stumble upon the answer, others keep pushing through being the dedicated gardeners that they are, and others, sadly become frustrated and give up.
Well, let me start by saying that I’m certainly no expert in irrigation, but I do have lots of experience in this area, talked with lots of experienced gardeners/growers here in town, done tons of research, and experimented a lot in my own garden. I also have a background in training, which I feel comes in handy when communicating the details. And, being a “transplant” to the Las Vegas area from a place so very different from here, I totally get it. Folks growing here for the first time could really use a bit more support and guidance than the standard answers above provide.
So to that point, the details that I would like to share with you may help to provide a better road map for you to navigate more effectively through this confusing topic and the ever elusive answer to the question, “how much and how often should I water my garden?” My focus today will be specifically on traditional watering methods such as drip irrigation and hand watering for raised bed growing. I’ll cover irrigation for home orchards in a later post.
Let’s dig in, gardeners!
Two Important Rules to Watering in Hot and Arid Climates
#1 ~ Throw out everything you thought you knew about gardening
Well, that’s a pretty harsh statement, but for the most part it’s true. The desert is a very different environment from which to grow fruits and veggies than any other place within the U.S. The soils can be quite lifeless and can be hard as a rock and very difficult to dig or till. The native soil here is also very alkaline with a typical pH of 8.1 or higher and is considered calcareous (i.e. contains a good amount of calcium carbonate). Then to make matters even worse, desert areas usually have temperature extremes (hot in summer and/or cold in winter), lots of wind, monsoons, etc. A number of things to think about and give pause when planning a garden here.
A lot of gardeners here grow their veggies in raised beds to help avoid some of the potential issues from growing directly in the ground. Others are growing very successfully in-ground, but it does require some amending in order to do so (i.e., mixing in compost, etc.). Each growing option requires similar, but slightly different watering approaches and the information I’m providing here can apply to both growing methods.
With all that said, be confident in the knowledge that gardening in the desert can be quite successful and understand that a lot of the gardening practices that work in other parts of the country just simply do not apply here. For example, I love when I see magazine articles on watering that recommend watering 1x per week or less in the cooler months of fall and spring and in the heat of summer they recommend watering 2x, maybe even 3x per week. Yikes! In the heat of our summer, my veggie plants would be crispy dry on that schedule.
Sure, your expertise and past experience as a gardener will serve you well here and will help to close the gap considerably on your learning curve. Just try your best to be open to new ideas and methods in your new growing arena.
#2 ~ Never let the soil dry out, even in the first inch or so of soil
For now, just keep this in mind. You’ll understand “why this is important” down below.
To answer the pressing question of “how much and how often should I water my garden?”, I feel it’s critical to have a basic understanding of the environment in which we grow in and the unique challenges it presents, especially ones that can negatively impact or sabotage even our best planned watering schedule.
When putting together a successful watering plan, especially for our blistering hot summer months, I highly recommend that desert gardeners seriously consider the following two key points.
- Soil salinity
To me, these considerations are just as important as water itself. To only consider the water component of your plan would be like getting dressed in the morning and forgetting to put shoes on. You go about your day walking barefooted in your finely appointed business attire or casual wear. Sure, you’re dressed, but something is really missing. And your feet are probably feeling the pain by the end of the day. Just like your plants will if you ignore these key considerations.
So, let’s break these down.
Consideration #1 ~ Moisture Loss (a.k.a. Evaporation)
Anyone and everyone who lives in a hot and arid climate has had some experience with moisture loss in their garden soil. The 110°F+ summer heat, dry air, and drying winds are sure to wreak havoc with the success of even the best watering plan. It can present a constant battle in trying to keep your soil moist and your plants well watered.
To help navigate through these challenges, some people like to add amendments to their soil like peat moss, coconut coir, vermiculite, etc. Myself personally, I typically steer clear of adding these types of amendments to my raised bed soil. The soil/compost (a forest green waste compost) I’m currently using to fill my raised beds has proven to be very effective when it comes to holding onto moisture while still remaining nice and crumbly. Using this soil/compost helps to eliminate the added expense of peat moss, coconut coir, etc. and allows me to focus my gardening dollars on amendments that I consider to be much more critical like earthworm castings, rock dusts, and mycorrhizal inocculants. The real garden super stars. Who knows, in the future I may change my mind about using these types of amendments, but for now, I’m sticking with what works in my garden.
In addition to the super star amendments I use in my garden, I also like to use other moisture retaining methods, that in my opinion, do a much better job at keeping moisture where it belongs… in my soil. Let me introduce you to what I like to call, “the dynamic duo”…
- Intensive planting
- and, Mulch
A key step in this method of gardening is to plant your veggie plants closely together in order to shade the soil underneath, dramatically reducing the evaporative effects of our hot summer sun. The shading also helps to keep your plant roots cooler, too.
Intensive planting can be done with a complex variety of vegetable and herb plants inter-planted together, or as simply as planting a single variety. The key here is the close spacing. An intensively grown garden also maximizes on space and produces more yields due to the higher number of plants within the garden. A very nice thing if you have only a small space in which to grow your own food.
For those interested, I’m currently working on developing a helpful guide that will contain a detailed plant list with intensive planting space information that I will be making available free of charge to subscribers of my blog. Keep your eyes peeled.
The compliment to intensive planting is mulch. Though the closely spaced plants do a great job at providing shade, cooling the soil and keeping moisture right where you want it, our hot drying winds and dry climate can still do a fine job at wicking away that precious moisture. That’s why it’s important to reduce this risk by covering the soil with a nice layer of mulch. For well shaded areas, I would recommend about 1-inch to 2-inches thick and for more open areas 2-inches to 3-inches.
There are a number of mulch options available to gardeners, such as…
- Compost (non-manure)
- Straw (weed free)
- Pine shavings ~ animal bedding (untreated)
- Hardwood shavings (i.e., alder)
- Composted wood chips (wood chips from a tree service ~ let sit for about 2 years to compost)
- Red or silver mulch
Currently, I’m using a thin layer of vegetative compost covered with about 1-inch of composted wood chips. I am considering one of the other mulch options (maybe hardwood shavings), because wood mulch comes with a definite ouch factor and can be harder to work around. I used it because that’s what I had on hand at the time.
Consideration #2 ~ Soil Salinity
Soil salinity is an often overlooked and under discussed topic in hot and dry climate gardening. A travesty actually. Like evaporation, soil salinity is another game changer when it comes to how you water and how often you water your garden. Choosing to pass over this consideration when developing a watering plan, can be quite damaging to your garden and can create a lot of “head scratching” moments when trying to determine the cause of its damage.
Typical arid climate soils, manure composts (a.k.a. Biosolids and animal manures), green/food waste composts (restaurants/casinos), and composts in general that are allowed to dry out are all extremely high in salts. And to add insult to injury, at least in the Las Vegas area, our water supply is fairly high in salts, too. So needless to say, we have a salt challenge that we have to deal with.
In the garden, we can exacerbate the high salinity issue by allowing the top layer of soil in our gardens to dry out even just a bit, which increases the likelihood that damaging salts will be wicked up and begin to concentrate in the root zone of our plants. This my friends is bad news!
The issue is magnified when soil regularly goes through moisture fluctuations. Like when the top few inches of soil dries then it’s watered enough to just moisten the soil, then the soil is left to dry out a bit again until the next watering. You get the point. One of the keys to keeping soil salts at manageable levels is to keep the soil moist at all times, and never left to dry out, even just a little. This is especially true during the heat of summer. Over watering will also cause salinity issues by preventing the salts from being flushed away properly from the root zone.
High soil salinity can be very damaging and will…
- kill beneficial soil microbes
- reduce uptake of water and nutrients
- reduce plant vigor and growth
- decrease the nutrition of the fruit (i.e., brix levels)
- negatively impact yields
- interfere with seed germination
- cause leaves to yellow and discolor along the leaf margin
- damage or worse yet, kill your precious veggie plants
I plan to do a blog post solely dedicated to the topic of soil salinity and its effects within the veggie garden.
Side-Note on Shade Cloth
There are a lot of opinions for and against the use of shade cloth in desert gardening. But the following facts are undeniable. In addition to providing much-needed shade for ourselves, shade cloth also helps the soil to retain moisture by reducing the evaporative effects of our hot summer days. Especially if using raised beds to garden in.
Shade cloth is not a requirement, but I thought I’d mention the option here.
NOW We Can Talk About Water (finally!)
Okay, now that I’ve talked your ear off about some very important considerations when creating a successful watering plan, I feel more comfortable in turning our attention to the actual water portion of the plan. So, let’s talk water.
At this point, some of you are eagerly waiting to jot down a detailed irrigation formula that you can apply to your garden with either the turn of a few dials on your water station controller or a couple of turns of your hose nozzle. In all honesty, it would be highly irresponsible of me to provide you with a “one-size-fits-all” formula ~ there are just way too many variables to consider. And, it may be much harder for you to make adjustments if things go awry (i.e., heat waves, cold snaps, super high winds, etc.). What I can give you are some important key observation points and tips to look for in your garden to help you determine when to water.
I’ve already given you a handful of very important points to seriously consider when putting together your watering plan. Important points that will help your garden soil to hold onto the precious water you apply as well as manage a unique challenge we face in hot and dry climates… high salinity. With this information, you can now teach the “so-called” experts a thing or two and you’re one huge step closer to a successful watering plan.
Let’s do a quick recap of those very important points of consideration…
- Keep your soil moist at all times = never let your soil dry out, not even an inch
- Keep your soil consistently moist at all times by avoiding moisture fluctuations
- Help your soil retain precious moisture by keeping it shaded and protected from our hot sun and drying winds by using intensive planting and mulch
Okay, for those of you who have quickly scanned through my post to this point, I highly encourage you to go back and actually read the details so you have a “real” understanding of why these points are so important.
Now let’s take a look at what Moist Soil really means along with some of the fundamentals of recognizing exactly when to water by using some of the most basic, simple, and free tools available to you… your eyes and hands. Yes, we’ll be fine tuning our observations skills at this point.
Most of us are very familiar with what dry soil and very wet soil looks like, but there may be some of you who are still perplexed as to what “moist” really means in the veggie garden. First, I’ll state the obvious…
Moist soil is definitely not loose, dry and dusty when it’s picked up in your hand (i.e., easily blows away and slips through your fingers).
It’s also not muddy, squishy and dripping wet. When squeezed in your fist, Moist soil will hold a nice firm shape upon opening your hand. No drips of water. No gooshy mess. The clump will also hold its shape even after being placed onto the soil surface and gently rolled around a little. Moist soil has a beautiful dark rich color with a definite glistening sheen to it.
Now, on the other hand, if you squeeze and release the soil in your hand and it starts to break apart in large chunks or in half upon opening your hand, it’s time to water again. The soil will also have a nice dark color to it, but the surface will have a much lower sheen than moist soil will.
It’s also important to note that just after watering, your soil will be more “wet” and may easily squeeze through between your fingers when you make a tight fist around it, though it should not be a sloppy, gooey, dripping wet mess like mud. Then you’re applying way too much water. It’s best to wait about an hour or so after watering to check your soil’s moisture again.In addition to grabbing some soil from the top 3-inches and squeezing it to check the moisture level (like above), it’s important to dig down and check the moisture level at about 6-inches and 12-inches deep. This is the critical root zone area. Keep in mind that not all plant roots go to this depth, but I like to err on the side of caution. If the water you’re applying fails to seep down into this area, your plants will suffer. For optimum moisture for your plants, the soil must be sufficiently moist from the soil surface down to about 12-inches deep.
Another quick test you can do is simply scratch at the soil surface (about 1-inch deep) to visually see if the soil has moisture. I would not rely on this test to determine if you need to water or not, but it can help you to keep tabs on the moisture level at the soil surface fairly regularly if you incorporate this into your day-to-day gardening tasks. Fairly dry soil at this level is not really a good thing and you should dig down deeper to check the soil further. Nice moist soil deeper down may just mean that your soil needs a good layer of mulch if there is none.
Soil that still has some moisture in it (i.e., not bone dry) yet fails to hold a shape after squeezing it in your hand is pretty dry and has gone too long without additional water. This drier soil will also have a lighter color to it. Soil that is allowed to dry out regularly to this point before watering is considered the definition of moisture fluctuation within the garden. When this occurs, soil salinity will rear its ugly head and make its presence known.
On the other hand, soil that remains fairly wet on a regular basis can also spell trouble for your garden. It can literally suffocate your plants by depriving them of oxygen, especially within the root zone area. Root rot and a variety of diseases can also occur. Soil that is moist and has a nice crumble to it allows your plant’s roots to easily move through the soil, and get the moisture, nutrition and oxygen they need to thrive.I regularly “squeeze” my soil, as demonstrated above, to check the moisture levels and its worked quite well for me and my garden.
To perform this test in your garden, I would recommend that you water your garden as usual and wait about 1-2 hours before testing it. Grab, squeeze, and observe soil from the top 3-inches, then from 6-inches deep and finally from 12-inches deep. Spend a day (or two) adjusting the length of time and frequency you water, testing and retesting until you ‘re able to consistently achieve soil that is at the “ready to water” point (see above). This process will help you to dial in the watering schedule that’s perfect for your garden.
For those of you who really want to start from a baseline for watering during the summer months using drip irrigation, try running your system so that it delivers about 3-inches of water each week. You can check your drip irrigation manual to determine the length of time it will take to accomplish this. Using that number, work your way from there.
As you go forward with implementing your watering plan, know that you’ll probably need to make a few adjustments along the way as you become more familiar with your soil, your irrigation system and our climate. Unless, of course, you’re one of the lucky few who just have a knack for it. Most of us need a little time to dial it in.
Frequent Short Cycles vs. Infrequent Deep Cycles
When it comes to watering in the desert, there are two distinct camps. One swears by frequent short water cycles. The other, infrequent deep cycles. Both camps usually water on a daily basis during the heat of summer.
Personally, I lean toward the deep watering but I refuse to take a firm stand either way. There are pros and cons to both. As long as the soil remains consistently moist from the soil surface down to about 12-inches deep, either method can work.
When first implementing a water plan, whether you’re using drip irrigation or hose watering, frequent short cycles or infrequent deep cycles, the soil needs to start off sufficiently moist. I always recommend using a hose to really wet down the soil in the garden before starting. It just helps to get things moving along properly.
Starting irrigation on fairly dry soil can be a challenge and will take time to moisten up properly. Any plants in the bed will suffer for it. Dry soil can be extremely difficult to wet and if not properly wetted before planting, any water applied has a tendency to run right through the soil and out the bottom of the raised bed leaving behind some moist areas (usually around the emitters) and some dry areas. In the heat of summer, soil salinity will be a major concern at this stage.
This coming season, I’ll be experimenting with an OMRI approved soil wetting agent in my blueberry raised bed. Right now, it’s bone dry and has lots of peat moss in it. Yikes! I’ll be sure to provide an update when we get started.
Putting It All Together
For some of you, checking you soil’s moisture level as I illustrated above, may seem like work, but trust me, once you get the hang of it, it actually takes very little time to complete. Plus, it really helps you to get up close and personal with what’s happening in your garden. Come on… as a gardener, this is just one more opportunity for you to play around in your soil without anyone questioning why. And, as I like to say, “time in the garden is always time well spent”.
Now, if you prefer to use gadgets, you can always try to use a moisture meter. Personally, this tool has not proven itself useful in my veggie garden, though I do use a meter in my fruit orchard. There are a few digital meters on the market that may work better for raised bed veggie gardens than the meter I have, but they can be on the pricey side.
Another method of determining how much and how often to water is to look at specific plant water requirements. In my experience, the average information on how many inches of water per week different plants require can be somewhat tricky when translating those numbers for use in hot and arid climates.
For instance, I use Netafim Techline CV 0.9 GPH drip irrigation lines for my vegetable garden irrigation. I also supplement water 1x a day by lightly hose watering or using my fav watering can, which helps me to stay connected with my garden :)
The drip irrigation I use puts out 1/4-inch of water every 10 minutes. To apply 1-inch of water per week would require me to run my system for 40 minutes total each week. So if I go by standard recommendations to water most of my veggie plants about 2″ of water per week, that would mean I should run my drip irrigation system for about 80 minutes total each week. This would translate to about 11 minutes total each day. Early on in my process, I ran my system on this schedule during summer and you know what happened? Yup, I had little crispies growing in my garden! Maybe its enough water for other parts of the country, but for here… not enough. Our moisture-sucking hot and arid climate requires at least double that or more.
Initially, I used these numbers as a baseline for my watering plan, but now… I rely heavily on regular observations of my soil to help dial in my watering schedule. And most of all… my plants are happy.
To wrap things up, I’ll leave you with this summation…
Intensive Planting + Mulch + Consistent Soil Moisture = Growing success in your garden!
May God bless your garden with health and abundance.