How often to DynaGro 7-7-7 in my environment?

Discuss repotting, soil, lighting, fertilizing, watering, etc. in this category.
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dscid
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Joined: Tue May 31, 2022 3:33 pm
Location: Austin, TX

How often to DynaGro 7-7-7 in my environment?

Post by dscid »

Hi,

I've recently started using the liquid fert in reverse osmosis water. All my cacti are clay-potted in 75% inorganic/25% sieved compost/castings.
Humidity swings wide in Central Texas, and this works for me to prevent rot throughout the year.
In the case of 100 degrees Spring/Summer the soil dries out daily. (potted shrubs wilt daily )

What is the proper way to fertilize my plants? My potted shrubs show deficiencies (chlorosis, or deformed/stunted new growth), clueing me into not fertilizing enough (they have 50/50 soil mix). I am concerned that watering so often is washing out the nutrients. Especially if during growing season, I want to pump them up and am watering daily.

Should I actually be following the instructions for use given by Dyna-Gro? Fertilize every time I water?
The only signs on the columnars I see become apparent at night with a bright LED, I can see non-uniform green blotchiness along all my cacti. I was trying to just add DynaGro to my water once per week, as per "internet advice" (while some internet blogs say to fertilize cacti 2-3 per year??).

Any advice?
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Steve Johnson
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Joined: Thu Nov 03, 2011 4:44 am
Location: Los Angeles, CA (Zone 10b)

Re: How often to DynaGro 7-7-7 in my environment?

Post by Steve Johnson »

See this:

https://www.cactiguide.com/forum/viewto ... 85#p393985

As I said in that post, I grow the vast majority of my cacti in a 60% pumice/40% granite gravel mix -- essentially a hydroponic approach, so I have to fertilize every time I water. If you have soil in your mix, cation-exchange capacity (CEC) in the soil means that any nutrients not taken up by the roots will be released in subsequent waterings. My guess is that once a month in the growing season should be fine. Fertilizing cacti only 2-3 times per year is bunk.

When you said "clay-potted", I'm assuming it's terracotta. If that's the case there is a big difference between low-fired and high-fired clay. If your terracotta pots get moisture on the outside shortly after you water, they're low-fired and porous. If they're high-fired, they're nonporous. In the event that you're growing your cacti in porous clay pots, see this:

https://www.cactiguide.com/forum/viewto ... 90#p382390

What is your inorganic component?
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
dscid
Posts: 2
Joined: Tue May 31, 2022 3:33 pm
Location: Austin, TX

Re: How often to DynaGro 7-7-7 in my environment?

Post by dscid »

Thank you for pointing me to CEC. After learning about it, I have a much better grasp on the situation :)

Mix: 12.5% Red Scoria, 50% Pumice, 6.25% Decomposed Granite, 6.25% Zeolite | 15-25% Compost, 0-10% Worm Castings, (add Coir to non-cacti)
(some of my earlier mixes were closer to 18.75% per inorganic component.)

Indeed cheap unglazed terracotta has been used for all my plants. Your test/results is a hard pill to swallow!

This year I added a soil probiotic to my watering regimen called Holganix Bio 800+. It does have fulvic/humic acid, and some kelp/yucca extract, so in that regard it is similar to compost/casting teas. However, it seemed like the soil changed almost overnight into a darker, overall healthier composition.
Whereas last year I made humic/casting teas that did not have any obvious effect on soil quality/structure. The pots would absorb the water, and the soil looked more like crumbly dirt after the following hot day.

It gives me the impression that living organisms increase CEC (even if indirectly through by-products), and/or if a terracotta pot contains a healthy/living system, an appreciable amount of moisture will stay in the core of the substrate, which the roots will permeate.

Your results speak for themselves though. I'll investigate during my next repot session.
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Steve Johnson
Posts: 4514
Joined: Thu Nov 03, 2011 4:44 am
Location: Los Angeles, CA (Zone 10b)

Re: How often to DynaGro 7-7-7 in my environment?

Post by Steve Johnson »

I don't want to make any assumptions about new members' level of knowledge and experience -- just out of curiosity, how long have you been growing cacti?
If you just want photos without all the blather, please visit my Flickr gallery.
My location: Los Angeles, CA (Zone 10b)
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