After reading multiple posts about how the top layers of stacker dry out more than the bottom ones do, I had an idea that I'm wondering about - whether it is practical or not.
For the upper two pots, would it be helpful to block the bottom drainage hole, and insert a new drainage hole about an inch up the side? Or would adding some of the softer cornstarch water absorbing crystals on the top two pots help balance this at all?
I don't have the pots yet, still doing planning/coveting, working out all the pros/cons.
Thus far the difference in moisture level between the top and the bottom of my stackers has not been an issue.
I think part of it is just physics. In my stacks, the top planter is always dryer than the lower ones because it is the most exposed. And the lowest one is always the dampest because it gets drainage from 5 pots above it and the lower ones are partially covered by the pots above.
I have 2 stacks of 6. However, none of them are too wet nor too dry at any given time so far. I'm using coir and perlite mix in my pots with an organic fertilizer in the mix.
I agree with Quinx...I was almost afraid to post previously that the bottom pots in a stack would remain moister longer than the top pots for fear someone would make a boogerbear out of the information. I insisted, in my posts, that it was not a serious problem at all, but wonted people to be aware of it. ONLY during long extended periods of rain did I get any indication of it temporarily effecting my stacker plants. The emphasis is on temporarily.
I wouldn't recommend modifying the containers. Modify your grow mix if necessary after a season of experience with the stackers and modify your watering schedule to fit your climate and type of plants. Coir/perlite is a great mix for stackers. If you wont them to drain faster, add more perlite and you might have to water a little more often. If you wont the stacks to hold moisture longer, add less perlite to the coir or just use straight coir. Your first year of experience with the stackers will tell you what to do. After all, your plants are right up there at eye level so you can look at them, sniff them, poke and punch them, have an intimate relationship with them. That works out pretty good unless of course, your spouse gets jealous."-)
Talk about an appropriate time to mention overwatering of stacked containers. Here is what happened. My youngest daughter visited me over the weekend. The kid is only 45 years old, not even old enough to get her own mail from the AARP yet. She was just really impressed with all the grow pole stackers in my back yard. I told her the African Daisy pole was about to make flowers and she really wonted to see that. I let her take over the watering duties while she was here. She was like a kid with a new toy, walking around poking the moisture meter into all the pots and adding water where necessary. But she really wonted to see those African Daisy flowers bloom. My son told me he saw her out there adding just a little extra water to that African Daisy pole. She was evidently determined to see them bloom and thought some more water might help. I have been guilty of the same thing in the past untill I learned better. The result is that the African Daisies bloomed...after she left. :-) And also their foliage now has a yellowish cast to them, a sign of too much water. You can see the yellowish cast to the foliage in the attached photo. I am going to send her a picture of the blooms...but Im not going to mention anything about overwatering. Geezzz, what kind of Daddy would do that? Besides, she is just a kid.
This is a good time to talk about what I called "un-balanced" planting in stacked containers in another post. By unbalanced I mean one pot having plants that require a lot of water compared to all the other plants in the same pole. In the attached photo, you can see Sunflowers growing from the top pots of two four pot poles. The sunflowers can quickly suck their pots dry of moisture while the lower pots still have plenty of moisture. Not many of you are as goofy as I am to plant sunflowers in the top pot of course. I do it just for kicks. I wont people passing down the road to see a sunflower towering above my privacy fence and think it is ten feet tall.
The sunflower on the left is the kind that makes multiple blooms. I keep deadheading it and it keeps pumping out more blooms. The one on the right looks like it is one of those types that grows tall and makes one big bloom at the top. These are volunteers from last years sunflowers so I dont know which type is which untill they grow.
I just pass by these sunflower poles two to three times a day, depending on the weather, and tap just that top pot with enough water for the sunflower but not enough to drain down to the lower pots which still have enough moisture.
I have another pole with convovulus (miniature morning glory's) planted in the bottom pot and that pot gets sucked dry before the upper pots.
Stacked containers are so easy to care for if you use a moisture meter to check them and water only where necessary.
I do recommend flooding the stacks thoroughly at least once a week to flush out accumulated fertilizer salts which can harm your plants.
Once full summer sets in here, and one hot day follows another, I expect I can set up an automatic watering schedule to flood the stacks at least once a day...maybe two. On the stacks where I am trying to grow tomato's, I may even have to manually water them extra above and beyond what the automatic system does as they are really water hogs.