New Vegetable Garden Watering Settings.. Fixed or Flexible?


#1

I just built a new planter and have finally got the plants in. There’s a combination of tomatoes, squash, peppers, chilis, pole beans, corn, onions, lettuce, broccoli and carrots.

…A little late for SoCal but it is what it is…

Now on to the question. I set this up with Rain Bird 2gph drippers and currently just have it running each day for an hour in the morning and an hour in the afternoon, similar to what I used to do at my old house with flood bubblers. The soils seems to be staying moist for sure and the plants are starting out well.

Going forward it will get much hotter here, up into the 100’s for days on end some weeks in the summer and then between the high 80’s and 100 the rest of the summer. I want to use flex zones but am not sure how to set that up as “Vegetables” is not a choice. I was thinking of perenials but am not sure. Also, as far as drippers, the input is in in/hour but the drippers are rated in gallons per hour so how to convert this? I assume that the area, can just be input as the overall square footage of the beds themselves.

Should I even bother with flex zones or just keep watering every day? currently it puts out about 70 gallons per day which works out to 280CF or 2.8HCF (billing units). Even if I bump into tier 3 at around $5/HCF that is still only $14 a month but it would be nice to keep in tier 2, which I was well below before this planting due to the Rachio keeping my water use barely into tier 2 and sometimes even in tier 1.

Side note: our water district has an app on their website that allows you to compare your usage with those nearby and I consistently score in the top 10, 5 even, since getting the Rachio.


How to set up a drip system in Rachio
#2

I’m very interested in a good way to set rates on emitters like this. It sounds like we have almost the same kind of system – the green flag emitters?

As a quick estimate, I figure that an emitter that has a single small stream of water will make a water profile that is like an inverted cone… a small point at the top of the soil and spreading as it goes down. How wide that cone gets where your plants’ roots are is likely what matters. Let’s say it’s about 20 square inches (that’s roughly a 5" diameter circle). That is a guess, and it will depend a lot on the type of soil.

A gallon of water is 231 cubic inches, so a 2 gal/hr emitter will send 2 * 231 / 20 or 23" of water through that 5" diameter circle in an hour. 23", that’s not a typo.


#3

Have you looked at this post? http://community.rachio.com/t/drip-emitter-calculator-for-precipitation-rate-area/6155 That should help you determine what to enter as nozzles.

If you are watering vegetables, it won’t matter if you enter in perennials or annuals — you are going to need to go in and put in a custom root depth as well. And you will need to up the Crop Coefficient.

@sunny, could you help out here? I know you’ve done quite a bit with vegetables.


#4

You are definitely going to have to play with the advanced settings a bit if you want to use flex. I use the below reference to determine crop coefficient:

http://www.fao.org/docrep/X0490E/x0490e0b.htm

Since you have a pretty wide mix of plants you will probably just need to go with the highest crop coefficient to ensure the thirstier plants don’t dry out.

I also adjust the root depth at least weekly to account for root growth. For allowed depletion I set it at 35%. I don’t remember where I pulled that from but it seems to be working well for me. Finally for the precipitation rate I did pretty much what you suggested, took the area of my garden bed along with the total gallons applied from all of my drip emitters and converted it to inch/hr.

One thing I’ll note, I’m pretty sure flex will result in less watering than you are expecting. I live in AZ so it is pretty hot here as well but currently it skips watering every 2 days or so. And I’m only watering once in the morning for about an hour.


#5

For this, I don’t want it to skip watering, EVER. I will probably leave it on fixed as Flexible looks to be way too much effort to save a couple bucks on the water bill.


#6

Thanks for the vote of confidence, @Linn. Even though I have been growing flowers and veggies since I was a kid, I’m not sure I can answer this question. There are too many variables. I will toss out some very general suggestions.

Knowing the soil type (texture) has a big impact on watering times. Unless the box is filled with native soil, the USDA soil survey is of no use and a jar test would be more helpful. Since you built a box, my assumption is that it is filled with purchased soil from the local nursery or big box store.

If that is the case, then the soil is most likely a “loamy” type–that is most likely an even mixture of sand, silt, and clay.

As @Linn suggested, take a look at the spreadsheet that @azdavidr put together. For raised bed vegetable gardening watered with a drip system, instead of thinking surface wetting pattern, think in terms of the depth of the wetting pattern. The team at Rachio has put together a great knowledge base with lots of illustrations. http://support.rachio.com/article/262-choosing-soil

Flexible schedules work great for my lawn and even some of my well-established xeriscape, but veggie gardens are unique. Plants at different stages of development may require different amounts of water. Overwatering can cause the same symptoms in the the plants as underwatering, such as drooping leaves, yellowing and leaf drop. Overwatering also leaches nutrients from the soil and prevents oxygen transfer.

Some vegetables may wilt on hot days even if they are properly watered. If they “perk up” in the morning, they are most likely fine. Wilting leaves during dry, hot days are not uncommon in tomatoes, peppers and broad-leaved plants like squash and cucumbers.

The “general rule of thumb” veggie gardeners follow is 1" of water / week. During hot and dry seasons, depending on what is planted and stage of growth, 1 - 2" / week would be appropriate. 1 inch of water applied to 1 square foot is approximately equivalent to .6 gallons.

The best suggestion I can share is “observation”. Spend time in the garden (to me that is destress time). Observe plant growth and health. Push your finger into the soil to test the moisture level. With some experience, the soil moisture levels can be estimated quite accurately.


#7

Wow! Thanks for the link, @sunny! I don’t know when they added this article, but it’s a goodie!!


#8

Agreed! I’ve been a fan of this company from the git-go. Not only do they have a great product, they have awesome customer support and the folks in this community are so willing to help one another.

Not sure how I could manage two very different gardens in different locations without this smart controller.

(Better stop gushing over them–don’t want it to go to their heads. :wink:)


#9

@sunny Too late :wink:

@Sammy2 if you are never wanting to skip, I would absolutely use a fixed schedule. I would also probably avoid most (if not all) of the Weather Intelligence. Adding your zone settings in and then created your fixed schedule for every day will produce a tailored, “Rachio recommended”, run time. Other than this, no intelligence will be applied.

McKynzee :rachio: