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Misting by Scott Armstrong
 

7/18/2000

In this year's quest for a larger pumpkin, I have borrowed an idea used by some heavy hitters in hot climates... Misting. Misting is a great way to keep your plants from suffering from heat stress during the day, which hopefully in the long run will result in a bigger pumpkin.

Have you ever gone out to your patch in the middle of the afternoon and noticed that your leaves are all wilted and droopy? That is the plant’s reaction to dealing with heat. It is under stress. To try and alleviate this stress, and keep the pumpkin(s), and the plant in a constant forward direction, some growers mist their plants. Depending on where you grow, misting may, or may not be right for you. For those of you who live in warmer climates and could benefit from misting your plants during the heat of the day, I will outline what I have done, where I purchased these products, and any tips that I have discovered along the way.

All the products I used in setting up my misting system were purchased from a company by the name of Dripworks. They have a website, (www.dripworksusa.com), where you can order a catalog that’s chock full of irrigation supplies. I was very happy with the service I received. They were always nice, even after my multitude of questions that, at points I’m sure seemed ridiculous to the non-giant pumpkin grower! I found them to be most knowledgeable, and extremely helpful.

When designing and setting up a misting system you can make it as elaborate, or as simple as you like. It really depends on your needs, your time, and you desire. Options are endless. When I set out to make my own misting system, I wanted one that was simple, easy to use, and easy to put together. What follows is a sample of the steps I went through to arrive at my current misting system.

The process by which misting works is called evaporative cooling. When the leaves get wet, and the water evaporates, the leaves are cooled. Just like when we are exercising and we sweat we are cooled. Misting also to some degree can cool the air around the plant, which is also beneficial in reducing heat stress. Because we only want the leaves to get wet, and not the ground, most generally tend to mist in short cycles of approximately 5 minutes, every half an hour. Your timer and misters can be adjusted to meet your individual needs of course.

The first step is to decide when you need to mist. Go out and take a look at your plants. If you’re not seeing wilt until 2 in the afternoon, and it subsides at 4, then you don’t need to mist very long. If on the other hand you’re experiencing heat stress at 11:30 in the morning, and it doesn’t dissipate until 4:30, then you’ll have to mist through a larger portion of the day.

Now that you’ve decided when you need to mist, you can start to look for a timer/controller. For argument’s sake, let’s say you want to mist for 5 minutes every half-hour from 12 until 2:30. This would mean that you have 6 start times. 12, 12:30, 1, 1:30 etc. until 2:30. You will need a timer that has the capability to perform that task. One timer that has 6 start times that is able to run in short cycles of 5 minutes every half hour is the Rainbird 1900. It is very easy to program, and at $47.75 is fairly inexpensive.

If you want to run your misters from 11:30 until 4:30 in the afternoon, for 5 minutes every half hour, you will need a timer that has 11 start times. This is not so easy to find. I have found a timer that has this capability. It is the DIG GREENHOUSE TIMER. This timer is equipped with an “irrigation window” where you can set the time the window opens (11:30A.M) and when the window closes (4:35 P.M), and the duration (5 minutes) in specified intervals (every half hour). Now your plants will be misted for 5 minutes every half hour from 11:30 until 4:30 every day, unless you manually override the program, (simply move a lever on the valve), or change the program altogether. The controller is waterproof and battery powered (two 9 volt batteries), and can be mounted either on top of the valve or on a wall or beam (it is connected by an 18” wire). This is the timer that I have purchased, and, although the instructions are extremely difficult to understand, once I was able to get it operating properly I have no complaints, and am actually very pleased with it’s performance. I had Dripworks add brass fittings to inlet and outlet sides of the valve just in case I got a little overzealous with my tightening! The timer is $115, and with the fittings, it came to slightly more. It is a very flexible unit in terms of its watering options. If you only need 6 start times or less, I recommend the Rainbird, simply because it’s less then half the price of the DIG. However, if you ever decide you want to expand your system, you want more out of it, or you need more then 6-start times, then the DIG’s the way to go.

Okay, so, now we’ve decided when and how long we are going to mist, and we’ve picked out a controller based on our needs. The next step is to pick out our misters.

Since we only want to get our leaf surfaces wet, we don’t need very high output misters. There are many different types of misting heads available. I went with the tornado mister in 4gph. The wind blows the mist around to some degree, but it is very effective in accomplishing getting the leaf surfaces wet. One note on picking out your misters...you should try and overlap the spacing of the misters in your patch, this way you are sure to get all the leaf surfaces wet. Also look at your plant, in my particular case, I have one plant that is very thick, that no matter what gph I use the ground probably wouldn’t get wet. My other plant is more open, and I probably should switch to a lower gph, because the ground at times can get wet. Dripworks has a sampler pack that you can purchase to try out an assortment of heads. Or you can just pick out some different ones and try them. Most cost less then a dollar.

The next issue we need to address is spacing. Do we want our misters on risers? Or do we want them to come directly out of the mainline? How far away from each other should the misters be? Where should we put the misters? How many misters do we need? These are all decisions that are easily made based on trial and error in your own patch. The best advice I can give is to allow some overlap with the mist so that you get all surfaces wet. Other than that, careful observation will lead you to your decision. My patch is long, and narrow, so if you looked at my patch from above, you would see 2 misters in a row (one on either end of the width of the patch) then forward from that, one mister in the middle, then 2, then one, …..all the way down the length of my patch. True, I could have put 3 in a row, but I found the way I set it up allowed for better water distribution. Once you figure this part out, you can decide how many misters you need to purchase.

Finally, before we actually order our system, how do we set it up? And what do we need (other then what we’ve already addressed) in order to accomplish this? As stated earlier, I went for simple,……really simple. What I did was, I ran ½” mainline tubing down one side of my patch, and tapped into it. Another method that could be used would be to put this mainline on risers down the length of your patch and just tap your misters directly in. I know Jon Hunt used a similar method last year. Basically, it’s up to you. Initially I thought running the mainline down the center of the patch on the ground would be best, but after thinking about it for a while I decided that a pumpkin could end up anywhere in the patch, and I really didn’t want to have to start moving my entire misting system to accommodate it. Here is a list of this of what I used to construct my system:

  • DIG GREENHOUSE TIMER
  • 100’ of ½” mainline tubing
  • 200’ of ¼” spaghetti tubing
  • 1female smart loc fitting (for attaching hose to mainline)
  • 1 male smart loc fitting with end cap (for end of mainline tubing)
  • 2 tee filters (200 mesh)
  • 25 tornado 4gph misters
  • 25 ¼” transfer barb’s
  • 1 yellow handle punch (for putting holes in mainline tubing)
  • 25 green garden stakes (purchased at home depot)
  • zip ties


First, I laid the mainline tubing down one side of my patch (when laying out the mainline, it is a good idea to let it stay out in the sun for a bit, it makes the tubing easier to work with.) Then, I attached the male smart loc fitting with end cap to the end of the tubing, and I attached the female smart loc to the other end (this is the end where you will attach your hose). I then attached a tee filter just before the mainline, (connecting it to the female smart loc fitting).

Then, I placed my risers in the patch where I wanted them, and took my yellow handle punch (you can use a scissors, but I wanted to make sure I didn’t have any leaks) and punched holes in the mainline where I wanted to run my misters. I inserted a ¼’ transfer barb into the holes. Now all you need to do, is take your spaghetti tubing, cut it to the appropriate length (the height of the riser, plus the distance across the ground to the mainline), inserted one end on the transfer barb attached to the mainline, and screwed the tornado mister into the other end. The mister goes in really easily. Then I took a zip tie, and tied the tubing to the top of the riser. At first wasn’t sure this would hold, but, if you tie it at the very top, where the mister goes into the tubing, things are pretty stiff there, and you can pretty much make it as tight as you want without worrying about impeding water flow. Continue this process until you are done with the patch. Then, attach your controller (be sure and program it) to your water source, (I have a tee filter after the timer as well), and attach this set up to your mainline, and your done! Congratulations, you now have a system that will keep your plants cool on the hottest of days!

Ultimately actually setting it up was easier then I anticipated. It is also a lot easier to do if there isn’t much plant taking up your patch. If your plant is large, it will be difficult, (but not impossible), to set this up around it, especially running the tubing through a maze of vines. You can also zip tie the tubing to the bottom of the riser as well. Be careful when walking around in the patch not to trip over the tubing. Next year I think I will bury the spaghetti tubing just for that reason. In addition, I added a “vee” on the outlet side of the valve. This allows me to use a hose whenever I feel like it, without running the misters or taking the whole setup apart. It does not affect the programming in any way.

Since I started using a misting system (this year) I have noticed no wilt whatsoever. In the past, no matter how much I watered in the morning, I would still get wilt, and at times even leaf burn. So, I guess misting does work!

Total cost for my set up was around $175 dollars not including the stakes. Obviously the timer was the most expensive part, but all other parts were inexpensive. Much more elaborate systems can be made if you desire, and perhaps even more simpler and cheaper systems can be made with some ingenuity. This is just what I came up with, and I’m very satisfied…. especially when I hear about guys who spend over $300 just on the timer ALONE. Now get out there, keep those plants cool, and grow a giant!

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