Fertilizing Acid Loving Plants

RAlmaroad

LawnSite Silver Member
Location
SC
Part of my program is to fertilize foundation planting and beds. Generally there is about 1 gallon+ of fertilizer left in the bottom of the tank. I just drain this in a 5 gallon bucket and dilute it and feed it to these plants. However, there are a few Camellias, Crepe Myrtles, and Azaleas that want acid fertilizer. For these plants since these plants also like a micro nutrient rich product WHAT WOULD acidify the mix for them. I have been just using a little wettable sulfur (1/4lb/5gallons) but those plants are just sitting there--some of the Crepes are no bigger than they were 2 years ago. Foliage is nice, blooms are nice but growth is undesirable. Any suggestion or should I just be grateful as I prune also. Oh yes, all of them have drip irrigation.
Roy
 

greendoctor

LawnSite Fanatic
Location
Honolulu, Hawaii
I think you are doing fine. One of the worst things to do to ornamentals is try to overstimulate them with too much water and nitrogen. Azaleas and camellias also do not appreciate being pushed with too much phosphorus either. That will simply lock up iron and cause worse chlorosis. Crepe myrtles might want heavier soil and more water, but be glad it is not growing like crazy. In my area, azaleas and camellias do not grow very fast unless pushed with too much fertilizer. In that case, it sets them up for attack by leaf spot and powdery mildew. If I remember your soil type correctly, 1/4 lb sulfur is a bit light per 1000 sq ft. 1 lb is more like it.
 
OP
R

RAlmaroad

LawnSite Silver Member
Location
SC
That was a 1/4lbwettable sulfur/5gallon bucket. I then would put it around plants at about 1 gal/plant/month. Sorry for the confusion. This generally would feed 5/6 plants depending on their size.
 

Smallaxe

LawnSite Fanatic
Slow or no growth in shrubs makes me look at the roots, when the soil is dry enough to dig down, without too much damage to the invisible root hairs...

Start at the trunk and carefully 'rake' back the top bit of dirt until to reach the end of visible roots, then go down into the perimeter of the rootball and see what's going on...

I usu. use a 3 or 4 tine prong for this... Be sure the cover the disturbed area adequatelywith rich mulch material and flood it when you're done...
 
I fertilize all ornamentals with slow-release granular. Either 8-2-12,8-10-10, or 13-3-13. Only reason I would use liquid would be if there is severe Fe/Mn def. or if they are new plantings and I am trying to get quicker fill-in.

Down here, slow-release granular is really the way to go due to our sandy soils. IMO, all acid loving ornamentals along with most other ornamentals down here need 4x/year. Esp, ixora, gardenia, etc.
 

heritage

Inactive
Location
New Jersey
Part of my program is to fertilize foundation planting and beds. Generally there is about 1 gallon+ of fertilizer left in the bottom of the tank. I just drain this in a 5 gallon bucket and dilute it and feed it to these plants. However, there are a few Camellias, Crepe Myrtles, and Azaleas that want acid fertilizer. For these plants since these plants also like a micro nutrient rich product WHAT WOULD acidify the mix for them. I have been just using a little wettable sulfur (1/4lb/5gallons) but those plants are just sitting there--some of the Crepes are no bigger than they were 2 years ago. Foliage is nice, blooms are nice but growth is undesirable. Any suggestion or should I just be grateful as I prune also. Oh yes, all of them have drip irrigation.
Roy
Sulfur is one way yes. Will work slower though as the Sulfuric Acid reaction takes time as the Sulfur changes to Sulfate.

Ammonium Sulfate is the quicker way to go. I would not apply it though, added to your leftover mix. Some of these plants do not like a high salt load.
 

greendoctor

LawnSite Fanatic
Location
Honolulu, Hawaii
His mix already contains a substantial concentration of ammonium sulfate. On salts: the most harmful salt I find in most fertilizers is potassium chloride. I do know that azaleas are another chloride sensitive plant. When I am trying to maintain chloride sensitive plants in soil that is already full of chlorides, last thing I do is apply anything containing potassium chloride. Which means I end up blending my own in order to get a suitable analysis.
 

heritage

Inactive
Location
New Jersey
His mix already contains a substantial concentration of ammonium sulfate. On salts: the most harmful salt I find in most fertilizers is potassium chloride. I do know that azaleas are another chloride sensitive plant. When I am trying to maintain chloride sensitive plants in soil that is already full of chlorides, last thing I do is apply anything containing potassium chloride. Which means I end up blending my own in order to get a suitable analysis.
Yep same here. Only using Potassium Sulfate. I don't even use Potassium Chloride on Turf any longer.
 

greendoctor

LawnSite Fanatic
Location
Honolulu, Hawaii
Mine is potassium nitrate blended with ammonium sulfate or calcium nitrate dependent on soil chemistry and plant requirements.
 

lilmarvin4064

LawnSite Senior Member
Location
transition-zone
Mine is potassium nitrate blended with ammonium sulfate or calcium nitrate dependent on soil chemistry and plant requirements.
Have you come across any specific incompatibilities with mixing Ca nitrate? and does the product you use contain PHCA?

whats' your preferred liquid P source if you need it? MKP? TKPP?

K thiosulfate vs K nitrate? other than the obvious

I don't use all that many liquids yet, but I'm having some trouble trying to source what I want and don't what to trial and error mixes. Most of the soils I'm dealing with are moderate to very acid soil, many very low in P, sometimes low in K.

thanks for anything you can help me with-
 

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