How Often Do You Need to Fill Up Your Ollas?

As I use more and more ollas in my garden, I'm learning a lot about them. One of the things that has surprised me is how often I need to fill them. When I originally looked at the Dripping Springs Ollas FAQ site (which I totally recommend), they mentioned that they fill their ollas 1-2 times a week in Texas. I figured I'd get about the same results here in Arizona. And I do... sometimes, under certain circumstances. Under other circumstances... not so much. So what circumstances effect how often I have to fill up the ollas?

Weather

This is no surprise, right? In the summer, the plants get a lot thirstier, so I have to water the ollas a lot more often than in the winter. Honestly, I can't remember how much I watered them last summer, but I can tell you it was more than this winter, when I sometimes went as many as 5-6 days between top-ups for some of the ollas. 

Plant Size

I prefer to keep the ollas around young plants more topped up than mature plants because the young plants' roots are shallower. If the ollas aren't relatively full, the plants might not be able to reach the moist soil because their roots are too shallow. On the other hand, mature plants have had a chance to develop deep roots that can reach the moist soil near the bottom of an almost empty olla.

They're so cute when they're young, but they need so much extra work!

Lately, I've been filling them up every other day or so, but I've come up with a couple of ideas for how I might be able to scale that back just a tad. (See the next entry.)

Exposed Soil?

One of the things that has really surprised me is that the ollas around big, established plants consistently drain a lot slower in my garden than the ones around small plants. For instance, that little zucchini plant in the picture above (which is about 10 inches in diameter) drains much, much faster than these monsters: 

No thank you. I couldn't possibly have any more. I'm full. 

That is a snap dragon plant and parsley plant. The parsley is over two feet in diameter! Both are very dainty drinkers. I'm filling up their olla about twice a week right now. I could probably get away with less. (Remember, I'm filling up the teeny, tiny zucchini plant's olla every other day, and I suspect I'm pushing it.)  

I'm assuming this phenomenon is caused by the big plants shading the soil around the ollas. Look at all that bare soil around the zucchini plant. I'm guessing that water is evaporating like crazy in into the air around it. There's barely any bare soil around the parsley plant, so there's probably very little evaporation happening there. 

Assuming I'm right, I'm thinking the right thing to do is to create some temporary shade for the soil around small plants until they have a chance to grow around the ollas and create some permanent shade. Perhaps I'll pile up some hay around the plants and ollas (leaving some room for any seeds I've got planted nearby) or erect some sort of shade structure. We'll see.

Update 4/15/15: So I tried adding hay around the ollas with lots of exposed soil and adding a little bit of shade--no joy. I still had to keep adding about the same amount of water to them. Then I had an "aha!" moment. The issue probably isn't exposed soil or shade. The reason established plants probably need so much less water is that their roots have had time to grow right up next to the ollas. For instance, check out this picture of an "inverted root ball" I found on the Internet: 

All that light brown stuff is a big mass of roots that grew right up against the olla. Once the olla was pulled out, the roots were formed in a perfect olla shape in the soil. 

So the reason young plants need more water than established plants is that they haven't attached themselves directly to the olla yet, which means more water is needed to pass through the soil to the roots. Once the roots get more established, they'll be pressed up right against the olla, and no extra water will be required to pass through the soil. So the extra water requirements for young plants is a purely a temporary situation. 

Soil Type?

I suspect results will also vary depending on your soil type, but since I only use one type of soil around my ollas, I really can't speak to that. (All my ollas are planted in native soil--i.e., clay and rocks--amended with manure and compost. Maybe they would need more fill ups with looser soil that drains better? I'm just theorizing here.)

So there you go. Those are the factors that I have found that may impact how often you have to fill up your ollas. In other words "mileage may vary depending on use." I'm still a huge fan and think they are a great way to save water. I'm just always looking for a way to make them more efficient!