I think that if you feel the need to work within the constraints of an all organic regimen for your plants' nutritional supplementation, your idea is well-considered, even if not ideal. Whenever we discuss what is or isn't an appropriate part of the methodology we use to make certain our containerized plants get all the nutrients essential to growth and good health, we would probably first want to be sure our objectives are on target. It's difficult to argue with the idea that our focus in supplying supplemental nutrition to our plants should be on ensuring all the nutrients plants normally assimilate from the soil are A) IN the soil and available for uptake at all times, B) in the soil in a favorable ratio - that is to say in a ratio that mimics the ratio at which the plant actually uses the nutrient, C) at a concentration high enough to ensure no nutritional deficiencies, yet still low enough to ensure the plant's ability to take up water, and the nutrients dissolved in that water, won't be impeded (by a concentration of solubles in the soil solution).

At this point, one can accept these premises as worthy goals or argue against them. If accepted, we should then necessarily examine our efforts at supplementation in the light of whether or not our efforts bring us closer to or limit our ability to see the goals implemented. What do you think about your ability to fulfill the ABCs via the plan you outlined (if you agree with the objective)?

Al

I just heard about making nettle tea as a great organic fertilizer from a class I took on Permaculture. There are some one other herbs including, comfrey, that supplement the nutrients missing from the nettle tea.

I haven't used it myself, so can't verify how effective it is.
I've added a link to the method for making it.

Here is a link that might be useful: nettle tea as plant fertiliser

I do agree with your objective, Al, and I think you've made a very convincing case in previous posts that, for container culture, synthetic fertilizers are better suited to achieving that objective. For that reason, I usually rely on synthetics (Foliage Pro and Miracid, primarily) to meet the nutritional needs of my container plants. Nonetheless, I've become increasingly curious about adapting organic techniques to container culture (especially since I've switched almost entirely to fabric aeration containers), so I'm planning to experiment a bit with my blueberry bushes this spring. I'll continue to fertilize most of them with Miracid, but a select few will receive either a combination of Miracid and organics or entirely organics. The soluble organic fertilizer blend that I mentioned in my initial post will be for the latter two categories. My primary intent is to put together an organic fertilizer blend that will come closest to meeting the nutritional needs of my plants without providing any particular nutrient in wasteful excess.

Thanks for the suggestion, nycgarden. I grow both nettles and comfrey, and I do use both to make compost and fertilizer tea for my garden. My favorite use for nettles, though, is eating -- the young spring leaves make delicious steamed greens. Nonetheless, the fertilizer tea is a bit of mystery brew...without submitting a sample to a lab, there's just no way to know what kind of nutrient profile that it's going to provide, and, at this point, I'd really like to have a good grasp of what my potted plants are receiving. That being said, a homegrown, homemade fertilizer would be my preference, so I'm glad you brought this up. It might be worth experimenting with comfrey and/or nettles tea at some point down the line.

Best luck - hope all goes well.

Al

Thanks, Al. I know that you hear this often, but I'll take this opportunity to say that your insights and advice here in the Container forum have been enormously helpful to me. My blueberry bushes love the 5-1-1 mix, and my houseplants have really thrived in the gritty mix.

shazaam, I'll chime in here, since I do mainly organic containers.

Precise NPK ratios aren't really very useful for organics. The soil web processes will dish out available nutrients in different ratios than your inputs anyway. Even given the extra heat and smaller volume, organic breakdown (and release of nutrients) does occur in containers. I've grow in 18 gallon tubs for several years now with good results. The leaves mixed into the containers always break down over the season and I see many worms in my containers. All evidence of organic breakdown.

I'd just use the liquid fish, a scoop of ashes, and mix in some dry crushed leaves for fertilizer.

One caveat on the air pot. I used one last year with poorer results than just plastic tubs. In my hot climate, the soil around the sides of the air pot dried out and no roots grew with 1-2" inches of the sides. So this really cut down the effective size of the pot and cut down how much air got to the roots.

Also I had my plastic tubs elevated, so air was able to get into the bottom, but the air pot sat in a tray so no air got to the bottom.

If you live in a cooler, somewhat rainy climate though the air pots should perform much better.

Here is a link that might be useful: Organic container pictures

Thanks for your input, emgardener (I failed to notice your addition to the thread until just a few minutes ago). You voiced some of the nagging doubts that were bouncing around my head with regard to trying to achieve an "ideal" npk ratio with organics.

Your caveat about fabric pots is interesting. I trialed some blueberries in Smart Pots last year and had outstanding results. By contrast, I have a devil of a time with plastic. For example, I started the season with three bareroot rabbiteye blueberries of comparable age. I planted two in a single 15-gallon Smart Pot and one in a 5-gallon plastic nursery pot -- the difference in growth and vigor was really amazing. There certainly might have been other factors at play, but I've had similar problems with plastic on other occasions. I'm not sure if the issue is climate or cultural (i.e. me), but I just don't have good results with plastics. Terra cotta and homemade wooden planters, on the other hand, have worked well for my plants, and, if they were lighter and less expensive, would be my containers of choice. The affordability, ease of handling, and overall good results with fabric have won me over, though. Nonetheless, as you observed, I've definitely noticed that they do dry out around the outside edges. I have several ideas about how I might mitigate that somewhat, so I'll be experimenting this year.

Finally, I found my way to your blog sometime last year (more than likely from a link here at garden web), and I like it so well that I bookmarked it. I have a little experience with hugelkultur, so I found your post about vertical hugelkultur to be really fascinating.