Speaker: Melanie Stock, Associate Professor and Extension Specialist, Utah State University; Director, Small Farms Lab
Recorded introduction: Narrated by Bethany Harris
Moderator: Gabrielle LaTora, Agriculture and Natural Resources Agent, Fulton County, Georgia
Duration: 29:23.7
Series: Cut Flower Symposium
Segment: 06 of 08
Webinar Date: July 23, 2026
CEU Categories: [PENDING]
Introduction and Recorded Biography
Gabrielle LaTora: We’ve got Dr. Melanie Stock from Utah State University. We have a short video to introduce you, and then Dr. Stock, the floor will be yours to share your screen and share all of your great information with us.
Melanie Stock: Sounds great. Thanks.
Recorded introduction, narrated by Bethany Harris.
Bethany Harris: Dr. Melanie Stock is an associate professor and extension specialist at Utah State University, where she directs the Small Farms Lab. A soil scientist focused on high-value crops and water use efficiency, she’s published guidance specifically on growing cut flowers under drought and heat conditions. From the semi-arid west, she brings tips and tricks for keeping flowers thriving when the weather turns hot and dry.
Melanie Stock: Aw, thank you. That was such a wonderful introduction. I’m going to go ahead and share my screen here
Alrighty. And just position zoom. It always likes to switch it up. Alright.
Agenda and Fact Sheets
So preparing cut flowers for drought and heat. Tips and tricks. from the desert. So I’m really excited to be able to share some of the the things that have worked for us here and I’ll spend a little bit of time too discussing that we are on different sides of the country, but there’s so we have so much more in common than we have different. So I hope you find at least one tip in here that is helpful for you. And of course, put your questions in the chat Chances are if you have a question, someone else in the audience does too. And I think that’s often when we learn the most. So, alrighty.
So first off, just an agenda today, I divided the tips into a couple different a few different topics here And so the first thing I want to spend time on is not something to just immediately do when there’s heat and drought, but just something to be thinking about all the time. And that is how can we build more resilient soils so that they can stand up to these challenging conditions. And in my view, it all comes down to organic matter and a really healthy soil structure So I want to spend time on that.
And then we’ve been doing some research on both mulching and irrigation, as well as protected cultivation, as ways to help alleviate the heat and the amount of water being used. So because we are almost always in a drought, and then some years are worse drought. So a lot of our work revolves around that. And then lastly, I I wanted to say too that UGA is on it and they have all the slides, so there’s no need for me to have these on my website, but I also have the slides on my website. I put a plug on Instagram to get you to that link too if you’d like
And then in almost everything that I present, we have a fact sheet about that. And so you’re welcome to take a look at our fact sheets as well. They’re posted on my lab website, smallfarmslab.com, under the fact sheets tab.
Utah and Georgia: Similar Challenges
I just want to make a quick note. So here I am in Utah, and here you guys are in Georgia.
And so right off the bat, I’m going to say, it’s hotter by you. You have a much longer season than us. And here at Utah State, I’m right on the Idaho border. And so we have everything from USDA hardiness zone 4, 5-ish down to here in St. George, which isn’t too far from Vegas. And they’re growing pomegranates and everything else.
So a good zone 8-9-ish. So we cover kind of a span here. The top part of the state is semi-arid. And then the the southern part of the state is arid, so that’s where Arches and all those national parks are. But we’re at elevation, so we’re about five thousand feet, and so it’s really our elevation that dictates our conditions more than the hardiness zone.
And I want to give a quick shout out to my lab, because these folks are the ones behind a lot of the work that I’m gonna share. So just looking at the forecast this week, again, we’re not really that different, although… So in terms of temperature, where you’re in the high 80s to 90s, and so are we. The difference of course is humidity. It feels much hotter in Georgia than it does up here in Logan, Utah
But because we’re at high elevation and we don’t have humidity in the air, the solar radiation, the sunlight is extremely intense. And so it’s so the surface temperature can get really hot because of that too. But really we’re both battling challenging conditions. And so I hope that some of these things that we’ve that I’ll share here resonate
Building Resilient Soils
Okay, so conservation practices to save water and build soil resilience. Building resilient soils in my mind. all comes back to organic matter.
Organic Matter and Soil Structure
And I think that term gets used a lot and most people know what it is, but organic matter is what gives soil a dark color. So it’s plants and animals that have lived and died over time and decomposed and they result they their remains coat the individual grains of soil. So it’s what gives topsoil a darker color.
And with that organic matter comes so many things. Of course there’s nutrients associated with it. But it also helps the soil develop just a wonderful structure. And I like this picture of a core here. This is coming out of, we have a long term, we had a long-term peony study So that’s a no-till situation. Here we are taking a core to measure some of the characteristics of soil. And you can see all those individual grains. You can see that there’s little tiny pores in the soil. There’s big pores in the soil.
And that here, so for Utah, this is a dark soil, by the way. That’s a nice brown one here. And so managing for organic matter. adding organic matter. I’m gonna talk about how to do that in the next slides here, but when it coats those particles like that and we allow the soil structure to develop, a lot of wonderful things happen. The water can infiltrate more quickly. And it can also drain better.
So in something like a heavy clay soil, organic matter is always the answer. And I have a really silly cartoon right here, but what I like, and it’s it’s meant to represent all these little particles of soil. And when organic matter comes in, it actually coats those little tiny particles and it glues them into bigger aggregates or bigger chunks. And what that means is it allows water to travel through much more easily. It’s I like to think of it as it creates a highway in the soil, right? So I could I could drive around and take all the back route back roads from city to city.
And I would eventually get there, I’d have a beautiful trip, but it would take quite a long time, or I can hop on the freeway and get there really quickly Same thing with water. It can travel between all these individual particles in the soil. But if it can hop on the highway, these big pores that are created because organic matter is coating the grains and creating larger aggregates Best case scenario. That’s a really good situation that happens.
Water Storage in Sandy and Clay Soils
The other thing that allows to have happen is that the soil can store water better. And this actually I like to think about in terms of sand. So sand, we have sandy soils, we have no problem with infiltration and drainage, and actually
It’s the opposite end where it can be a bit challenging in that soil just doesn’t want to hang on to water. It’s like seeing it’s kind of when sand sees water, it’s some stranger down the street. There’s just no attraction there But when we introduce organic matter, it can coat those particles and suddenly those particles can actually hang on to water a bit better. I shouldn’t say suddenly, but…
It’s there starts to be this attraction. So it works both ways. It helps clay soils by allowing us to infiltrate water better. store excuse me drain that water and then on the other end with sandy soils it helps hang on to that water in the root zone. So because having consistent soil moisture is very important for most cut flower crops other than the drought tolerant ones. When we don’t when there’s water stress, we start to see a lot of disorders develop. And I’ll talk more about those later.
Replenishing the Nutrient Bank
And then another one is too, so in cut flower production, we really are asking asking a lot of our soils. We if I think about all of the biomass that gets created in a season, what we’re all growing on our soils, we have to be able to replenish the bank. And I like to think of the soils as this wonderful nutrient bank.
There’s 14 mineral nutrients and it does a pretty darn good job with most of those, but we also got to replenish that bank. And so organic matter can be a wonderful way to do that too. And on this note, then reducing tillage is also helpful for because it takes so much time to create that beautiful structure in the soil. All right, I’ve yapped on a ton about organic matter in the soil.
Adding Organic Matter Sustainably
So now I want to talk about how to do it and how to do it sustainably because I think especially in a small farm situation, microfarms, there can be a tendency Great intentions, but maybe a little bit of loving it to death. So think of this as a marathon, not a sprint.
Every year it gets a little bit better. Gradually adding organic matter, not adding inches at a time So I like to think of giving the soil a healthy diet so it’s not just eating one thing, but rather finding organic matter from different sources.
Salts in Compost and Manure
And with compost and manure, this can be a challenge, especially within high tunnels. So I know that you guys get a whole bunch more water than we do, and that helps flush. Salts and so forth out of the soil, but if it’s underneath a high tunnel under plastic, it’s really easy to build up on salts And there’s a lot of salts in compost and manure. And that’s because actually most plant nutrients count as a salt in the soil. And I’m happy to talk about that more later if you’re interested.
So I put this picture of me. This is me handling liquid dairy manure. And I have a huge smile on my face because I love working with manure. I am not anti-manure or compost. It’s just that we have to be, it’s a marathon, not a sprint. Being conservative with those applications.
Another option which I’ll talk about here in a few slides is cover crops. Can be a great way to add organic matter. You don’t have to worry about salt that way They can help scavenge nutrients and do a bunch of other things. Another slide on that coming. Same with the last two items here on the list.
Reading a Manure and Compost Analysis
So this comes from a fact sheet. that I wrote and it’s not specific to Utah. I went through all of the manure and compost samples that our lab produced and made a table of just what those what does it look like? What’s the average NPK those three primary macronutrients for plants, what’s the pH, what’s the salinity associated with it. And it’s in this case this compost type is divided by if it’s manure based or something else. And looking at it by the animal.
And so especially for those who are using high tunnels and so forth, I’d keep an eye on salinity here. And what I want to say is your magic number is two. You can go a little bit above that. It’s not going to make the soil immediately shoot up, but I want to just give a kind of a reference point to show that 16 is really high. So is 11.
But these are both coming from bird sources. And I’ve got a picture of my chickens down here, some poop from my coop. And I want to just point out that white that is on their manure is their urine And urine is what holds a lot of salt. And it’s what you can get the burn on the plants and so forth. But that’s why poultry has a higher salinity. It’s because the urine is in the urine.
The main thing though too is that the NPK has about equal parts, nitrogen, phosphorus, potassium. And so it’s a great idea to use this to hit your phosphorus need. and then supplement the nitrogen. If you’ve applied enough to hit the nitrogen need, be overloading the soil with other things.
Just some other little details here too, if you want to nerd out with me and get deeper into the nutrient plan. So absolutely can use these to help build organic matter in the soil, but do so conservatively.
Cover Crops
In following up with the talk of cover crops So it’s this idea that we’re growing something more for the soil than for ourselves. And each cover crop can do different things But one of the big things that they do is produce biomass that we can then return to the soil and add that organic matter. I have listed on the slide a bunch of other things that organic matter excuse me that cover crops can provide the ecosystem services that they can provide on our farms.
If you’re like me, I don’t have a lot of land and I’m really into production and so I can’t just take a whole bed out of production for a year to grow cover crops. So a common question I get is how do I incorporate them into my system? And so I have a few sneaky ways You might consider if there’s an edge of the season when you’re not growing as much, that can be a great time to sneak them in if you’re rotating crops. If crops are already established, you could seed in cover crops, so you don’t want them competing with the main crop, but they could be grown between crops potentially. There’s been a lot of research coming out of the Midwest on that. I’ve also seen cut flower farms use it as an agritourism. Option.
Here’s a picture of crimson clover at our research farm and it’s just it was absolutely gorgeous. Buckwheat is gorgeous. There’s a lot of different options and I know UGA has so many resources for you. So definitely take a look at what UGA Extension has on cover crops. This is millet, by the way, different types of millet, which could also serve as a cut flower and for wreath making.
And then I also wanted to plug the West, excuse me, SARE Has a lot of information on cover crops. And then this guy over at Washington State likes to go through all the research on cover crops and soil health. And then he has a blog about what it all means.
And I and he writes it in a really easy to understand way. So if on Friday night, if you just want to start reading about cover crops, I recommend checking out his blog.
Crop Residue and Residue Management
And then a last comment here on cover crops is just that so they do take water. It can be hard to fit them in a season on a cut flower farm. And so Andrew McGuire who I was just talking about in the last slide, this comes from his blog. Where he was looking kind of through the literature at the use of crop residue and managing the residue. So if it’s not disease, if it’s disease, get it out of there. But if it’s not
It can be a great way to add organic matter to the soil. It’s a renewable resource. It can protect that soil surface from erosion. It can help keep it cool. It can aid in infiltration.
And when he went into the literature about cover crops and so forth, the biggest thing that he found mattered was about residue management. That’s why this bar here is so big. And so whether that’s coming from cover crops or from your crops, it both can help the soil.
Tillage
Alrighty. Last thing on soil. I’m sorry to talk so fast. There’s so much I want to share with you and make sure we have time for. Hopefully these notes can just be also a good resource to come back to if one of these picks your interest.
So a quick word on tillage. It’s everyone has a different size farm. Everyone is got their own challenges and so I don’t like to give a one size fits all approach but what I would say about tillage is that moderation and intention are key There are benefits to tillage. It can help incorporate that organic matter deeper into the root zone.
If you’re breaking ground, there’s really no other there’s situations where there’s certainly no other way, but getting that organic matter deeper into the soil can give a a really fast boost to the situation. But there’s drawbacks too and that mainly is that it destroys the soil structure. It breaks up those aggregates.
And actually microbes are one of the when he in the analyses of what keeps them healthy in the soil, they’re really sensitive to changes in pH and they’re really sensitive to physical disturbance. So thinking about it from a soil health standpoint and… Maybe considering conservation tillage that I’m not going to till every year, but maybe every couple years to get things mixed around Alrighty, so that’s keeping the soil healthy and resilient to be able to withstand these challenging conditions that come up with heat and drought.
Mulches
The next thing is this I want to talk about mulches. I don’t want to focus on plastic too much, but just this idea that having that soil surface covered with something can help with water savings and it can also help us control that root zone temperature that can add stress for plants.
Plastic Mulch
So plastic mulch, we use black plastic mulch early in the year to get the soil warming up
It also does, it helps with weeds and so forth. Because we’re in the desert, it we have about a 40-degree temperature swing from day to night, and so it helps us keep the soil warmer at night as well. We’ve done studies, this picture down in the middle, we were looking at black versus white plastic with dahlia to try to moderate that root zone temperature a bit. But then there’s a lot of drawbacks to plastic as well.
Natural Mulches
And so we in my lab, we’ve been getting really excited about natural mulches. What can we do? And some of these don’t scale to large-scale farms, but I like to say be creative. Benefit of natural mulches so it comes from some once living source.
Is that it can add organic matter to the soil, they can help save water, and they can moderate soil temperature. So keeping it cooler in the heat has been big. And so here’s just a few pictures Wood chips, this is from Christmas trees, the boughs from Christmas trees.
Over here, there’s some straw. So nothing is a perfect fit. There’s pluses and minuses to everything. So I tried to list a few of these things here, but… What is around you that might be able to serve as a mulch source that could help break down and add?
Wool Mulch Research
So a few years ago, our sheep specialist came to me and he said the the market for wool is terrible right now and there’s always coarse wool that never can get used and right now even the good wool isn’t selling. People are paying to landfill it. Can you use it with cut flowers?
And I got excited. I said, I think so, because I know it’s about 10% nitrogen, which is a lot, and that’s the number one plant nutrient. And I was really curious if it could help keep the moisture in the soil so it could reduce evaporation. It could keep maybe it could keep it cooler too.
The Annual Trial: Six Warm Season Crops
So we did a trial with six warm season annuals a few years ago, and we looked at it in mulch, wool mulch versus bare soil And we simulated a drought where in this state, if when we’re in droughts, we get restrictions on water use. So I simulated that. I purposely stressed these plants out to see who could perform and what was the difference with wool versus no wool.
And so a few things, I’ll just to summarize this study, we had at least 5% more moisture in the soil at any given time, which results that’s hundreds of gallons. And it kept the root zone cooler by a good five to seven degrees, which can be a big deal for plants. Once the plants got big and their canopy closed. We didn’t see that difference as much. But having that early when we’re trying to get these plants established and they’re actively growing was a huge help. Now I don’t have yield data shown at all.
I do want to point out This miniature carnation here on the right hand side. So on the left of the post it’s grown in wool and on the right of the post it’s grown in bare soil. You can just see the height difference there
So for each of these six cut flowers, if you check out my website, we published fact sheets on production and we put in what the results were from this trial. And the spoiler alert is that everybody performed better in the wool. than on bare soil except for statice. Statice didn’t care where it was.
The Perennial Study
Now we’re doing this study with perennials and we’re we picked three and instead of simulating drought, we are monitoring soil moisture and irrigating based on need. And I know I’m running out of time, so I can’t show you all my fun graphs. So I’ll just quick say what happened. So we’re looking at bare soil versus plastic landscape fabric versus wool Wool is in blue here.
Red is bare soil, black is fabric, and this is temperature, where we really would like to stay below 80 when we can, the day to night temperature. And you can just see the wool, the soil temperature under the wool is just so moderate compared to these huge swings that we’re getting elsewhere We measured a ton of things. This is looking at the growth of the three cover, or excuse me, the three crops with the different mulches. Long story short, more growth in wool.
And then this is a table showing how much water we used during establishment last year. And we saved 30% water using wool. Fabric had about a 10% savings compared to bare soil. There’s a lot of potential there. And then lastly, the soil nutrients, it varies, but it varies in the wool, but there are a heck of a lot of nutrients in that wool that get slowly released.
Selecting Crops That Take Heat and Drought
So lastly, thinking about soil moisture and heat stress, what is it that those plants want? How can we make the best environment for them? Or knowing it’s going to be hot and dry. Could we select crops that just take the heat and the sun and the drought, especially after establishment?
So I have a list here of ones that really stand up. to it they can handle that soil moisture getting low they can handle the root zone getting hot another thing that we’ll do if we know it’s gonna be a bad water year is trying to select crops that we can put in early and they’re going to finish early while we still have water because we depend almost entirely on snow melt. for our water so it’s in and out and then what may whatever may happen with drought later in the year.
Sometimes we’re told we just won’t have water after August 1st. So that’s where that comes in. If you’re interested we can talk more about early crops
Day Versus Night Irrigation
And then I want to just share, gosh, I just want to tell you all the things. This is an interesting one looking at sprinkler irrigation. It was of turfgrass and zinnia cut flowers. And the question was
What happens if you water during the day versus at night? And everyone assumed that night irrigation is going to save water And what we found was that was not the case, actually. So nighttime we were up we were irrigating right before sunrise. So it was between 3 a.m. and 5 a.m. and then daytime we were watering in the afternoon so between 3 p.m. and 5 p.m.
And what we found is that by actually irrigating during the day It helped cool the air and the soil and the zinnias really like that. So if we look at the yield, how many stems per square yard We did this for three years. The yield was much better when we irrigated them during the day.
And for those of you who want more, I can’t imagine that you do. But here’s a soil moisture graph Throughout the summer one year. These two lines, the light color is day irrigated soils, the darker purple color is night irrigated soils, and you can see that soil moisture is drier when we’re irrigating at night. And if you’re interested in why that is, I can share a little bit.
So this daytime irrigation, thinking about it, maybe around 5 p.m. when it’s hot during the day, it can cool off that environment enough, and then you get into the night. So it was a surprising result from the study.
Critical Water Phases
Another thing about water is if we’re in a drought and can’t water everything all the time, there’s a few phases that are really important to keep things hydrated. One is during establishment and the second one is during bloom. So when it goes the plant goes into bud through harvest is a really critical time to not stress out the plant
That vegetative stage that happens between establishment and bloom is more tolerant. There’s a lot of there’s more to be said about that, but it can’t be too stressed out because that can delay bloom Some ideas here are considering when you’re planting, putting plants together by water demand. Who doesn’t need as much water?
Who is a heavy drinker? Put those guys together and then in a drought situation when we need to add more water, we can focus on the areas that really need more of it and not the entire farm necessarily Can talk more on that here if there’s questions about it, but I know I need to finish up.
Dahlia
So I had a little bit here on dahlia. These are our thirstiest drink, thirstiest crops. They are not a water savings crop, and we looked at are there any kind of ways we can save water with them?
No. The answer is no. They need a lot of water. And end of story. Happy to talk more about this if you’re interested.
Protected Cultivation
And then lastly the heat load help. So protected cultivation, the use of high tunnels or hoop houses to help advance the season, which helps keep things under cooler conditions. For us that also helps with water availability too.
Here’s pictures of our high tunnels at our research farm. And so this is a kit and this is a county agent down in south in St. George But these are our tunnels up at Utah State, and you’ll notice they’re an unconventional design, and this is a DIY design that our fruit and vegetable specialist developed And we’ve got the design plans on my website, as well as at tunnel.usu.edu.
That well, what I really like about them, they’re smaller. They’re cheaper and they’re heating structures in the wintertime, so we just put plastic on them, but that’s easy to remove the plastic and then put shade cloth on. for the summer to try to get rid of that that heat load. And by not having plastic on all the time, we get more years of use out of it. And same with the shade cloth. We’ve also done a lot with low tunnels for adding shade and fabric and so forth.
Shade
So a few things with shade that and there’s great research out of Georgia. You guys are like the Mecca since you had you had Allan Armitage. I’m I’m in awe. So there’s a lot of more information coming from your state, but a few just
Things about shades, it doesn’t change the air temperature, but it does reduce the sun load on our crops, which helps them be less stressed in the heat and the drought. It also can protect from wind, which has a drying effect, and it helps increase the stem length, both because of the shade. And because it can help with the wind, so they’re not trying to hunker down.
And there’s a few things here about shade, and we actually did a study with a farm. Around here and she was looking at it with irrigation. She was actually able to cut her irrigation by 50% with shade.
Summary
In summary Whew, that was a lot of information through a fire hose, but building organic matter in the soil is important. Use different sources for it when you can. grouping crops by water demand, thinking about what species would go together, that what needs more water, what doesn’t.
New transplants need water. When the flowers are in bloom they need water, but there might be ways to cut back when it’s just that vegetative stage. And then alleviating the heat load by the planting timing and playing with trying to move it up or move it back potentially and then shade and so forth.
Closing and Survey
With that, thank you all so much for listening to me. Thank you for looking at all those graphs with me. And thank you to UGA Extension for inviting me I have a QR code.
It’s a five-question survey that’s really important to USU. If you could please fill it out. I’m going to throw the link in the chat as well. Please fill it out. It allows us to keep doing cut flower research. So with that, thank you, and I’d be happy to take a question.
Questions and Answers
Gabrielle LaTora: Dr. Stock, can you hear me?
Melanie Stock: Yes.
Gabrielle LaTora: Awesome. Thank you so much. It was really interesting to hear your perspective from Utah and how we can translate those recommendations to Georgia because we certainly are dealing with heat and drought issues here too.
So we got two questions in the Q&A that basically are asking the same thing. So I’m gonna combine them together So if you are using a wool mulch, do you incorporate it into the soil after harvest? Do you till it in, or can you save it for the next planting?
Melanie Stock: That is a fantastic question, and I’m so grateful that you asked that because so our perennial study that’s happening right now, we wanted to know that same question. How long does it persist?
And so what we’re looking at in that study, I had mentioned we’re looking at plastic landscape fabric, bare soil, and wool, but within that, with the wool, we’re looking at Adding it annually, so putting fresh raw wool down, pulling it up and putting fresh again, versus applying it once and seeing what happens for the duration of the study. And I’ll say out here in Utah it doesn’t break down as quickly and it’s because we don’t have as much water. So I think it would break down much more quickly in Georgia It is not a drawback of this is that it does not lend itself to tillage.
So trying to incorporate it after a season, however much is left. I think it would be problematic. So it’s really, I think it’s best in a perennial situation where or in a no-tillage situation. You could also just pull off what’s remaining if you did want to till, and that would be possible too Great question.
Gabrielle LaTora: Perfect. Thank you. So we’re going to go ahead and kick over to our next speaker, but Dr. Stock, you got a couple questions in the chat. So feel free to answer those if you have time. And we really appreciate you. Okay, thank you. Thank you.
Transcript processed for UGA Center for Urban Agriculture / Cut Flower Symposium Archives
Source: Corrected SRT (Stage 1), GTBOP_Transcript_2026-07-23_StockDroughtAndHeat.srt (438 blocks)