i was about to post almost this exact question. Except backwards. I am planning on using Soil Acidifier at the end of this month and also wanted to use holly tone for fertilizer. is that ok ? I know some of yall don't think fertilizer is needed but it makes me feel better about doing one application in the spring/summer period.

Yes, you can do both without worry and it really doesn't matter with the order either, although sulfur takes time to work its magic on soil pH so is generally applied well in advance of the bloom season.

Depending on how radical your pH change is, once you have achieved the pH you want, just the Holly Tone application may be sufficient to keep it where you want it without a need to reapply the sulfur each season. This usually works best when the pH change is not big.......a significant pH change is very difficult to maintain.

Yeah, they are both ok to use in any order. The only suggestion I can offer is to consider using the fertilizer Holly Tone (I think they call their fertilizer "food" in the packages) closer to leaf out time. I tend to use the amendments during winter or if I do not wish to trigger growth for whatever reason.

Since it is a fertilizer, it has nitrogen and may trigger growth in the middle of winter. This may not be a problem in warm zones where there may growth starting soon but it can cause problems in colder zones if they are in the midst of warm temps.

If you are adding two products containing sulfur -a fertilizer and an acidifier amendment- at the same time, try not to exceed the suggested label directions much as "really too much" sulfur can burn the small hydrangea roots.

You would not believe how easy it is to have an "Oooops Moment" when adding these two products into the soil. ;o) Ha!

It is hard to guess what color the blooms will be at any time when one tweaks the soil. At 6.5, I would not expect much in the form of pinks... you can start to see some shades of blue or maybe purple, although purple happens in a narrow band of pH. The variety also makes a difference as some "resist" changing to blue. This is part of the "fun" of tweaking the soil pH (ie, guessing what colors you will get).

Keep good records of how much amendments you add so you can alter that (up or down) if the color is not quite what you want.

Ok that's great news. So if i am going to space this out like suggested.. I was thinking of adding the Soil Acidifier maybe at the end of the month, say March 1. Then i would re-apply every 60 days; May 1 and July 1. When would be the best time to add the Holly Tone ? I can either do April 1 or June 1; before or after they leaf out.

Does the product label suggest you reapply every 60 days? That seems excessive to me. Generally, a sulfur application is done at most twice a year and it takes 4-6 weeks for the product to become effective (longer if using sulfur chips). How much are you intending to lower pH (what is it now....what do you want it to be)?

btw, blue flowers on a bigleaf hydrangea are the result of adequate aluminum levels in the soil, not necessarily just the acidity. It is just that an acidic soil tends to make the aluminum more available. But you can have very acidic soil but still not have blue flowered hydrangeas if aluminum levels are too low.

Maybe just using aluminum sulfate, aka "hydrangea bluing", would be an easier route to go?

I was taking the directions based on Espoma's website. It does say 60 days, although that can be marketing too ! My ph last fall was 6.5 in this area. I don't want to change all my hydrangeas, just a couple Original's and a couple Bloomstruck's. I think lowering to 5.5 would be ideal based on what i have read.

I like your suggestion on the "hydrangea bluing" although what i have read all directed me to this product. I can do more research, i just found this as the ideal choice in my readings. Is there any article you have that is reputable for me to read over on using just aluminum sulfate ? With directions on how much per plant and usage amounts ?

This was the first article that came up for me..

http://homeguides.sfgate.com/apply-aluminum-sulfate-hydrangea-85746.html

Directions are on the package label. And this IS the recommended additive for increasing blue flowers on bigleaf hydrangeas! Dirr has a entire section on it in his treatise Hydrangeas for American Gardens.

Ok good to hear. Can i generally find a bag at Lowes or Home Depot ? I'll have to go look, but is there a brand or just any aluminum sulfate bag ? Should i get any additives in it ?

No it is just plain old aluminum sulfate, Al2(SO4)3. Brand name doesn't make any difference (just like the sulfur - it is what it is). And it should be at the box stores. Will definitely be available at a proper retail plant nursery.

Ideally, I would have done the first application in fall (that's when I did mine that are being affected by a siting too close to concrete). I only apply twice a season (will do so again as the shrubs start to leaf out) as I don't have to apply very much to get blue flowers.

Just follow the label directions....you'll be fine :-) Make sure you keep it away from any azaleas or rhododendrons - they are very sensitive to aluminum toxicity.

ok so if I apply the 1lb/5gal water.. per plant this week. Then can i still apply again in the early summer ? My soil is sandy so only one application makes me nervous it wont do anything. I too have my bloomstrucks right next to concrete so i want that deep purple. They were great last year but still young so im worried about this year.

Also I have some camellia near my hydrangeas, 4ft away. is that ok ?

Camellias are OK - it is just the rhodies that have that strong sensitivity.

You need to apply the aluminum sulfate before the flower buds develop. I'd do so now and then again in late spring or early summer before you begin to see 'broccoli'.

Ok great, so one application of 1lb/5gal water now, another application somewhere around May 1.. then once the first buds open i can still apply some holly tone ?

Last year i didn't realize this garden was covered in OLD weed barrier and after removing it i noticed that water wouldn't even seep through. My hydrangeas were pitiful last year so i am really trying this year ! ha

I have not had issues with azaleas or camelias besides the hydrangeas that got a/s buuuut I knew about the toxicity so I try to keep the a/s somewhat away from the hydrangeas.

PS - I have not "seen" a/s for sale at my Lowes or HD. I usually get at other local plant nurseries.

i went to both lowes and hd.. no luck ;( ill be calling my nursery today

Good luck. I only see it at a few places locally and see garden sulfur more often than a/s.

Follow the directions on the package :-))

Although not clear from the small excerpt you posted above, it appears that they are suggesting using the AS as a soil acidifier rather than as an amendment to intensify the blue coloration on hydrangeas.

I would not use AS for this purpose, just due to the potential toxicity issues involved with excess amounts of Al in the soil!!

I meant using AS just to acidify the soil. That is NOT its most effective and best use. Fine for use on hydrangeas.......not nearly as fine for use to appreciably lower soil pH!

now let me toss a wrench into the application instructions. it says 1lb per 3ft of growth on a shrub.. if my hydrangeas were 1 gallon last year they are maybe 1-2ft max. still go with 1lb or cut that in half ?

Cut in half. My bag of AS says the same but equates 1 pound to 2 cups. So I would sprinkle one cup around the dripline of the hydrangea, scratch it in lightly and water well.

thank you thank you !

As long as you or Mother Nature gives it enough water, it does not matter.

I always try to amend the soil before we are scheduled to get a good rain. That way, I do not have to water and I save some change $$. However, if we just get a light rain then I hand water.

We are scheduled to get a few days of rain too so I amended early (I usually leave amending for March but I had a/s on hand and it was going to rain so there). Ha.

Amending withing soil with AS - In fear of over-application, I've always just done the 1tbs-gallon ratio and then water well

You need to regularly do a soil pH test. About once a month maybe? Once every two weeks tops. Compare the results from month to month to see how it is going. Write the results somewhere so you can trace the way things are changing. If the soil pH appears to be stuck at a given level for a few months then consider adding more a/s. Mark the amt on the measuring cup with a pencil so you can keep track of that better.

You will need to continue the a/s application monthly (or whatever the product label said) forever as the soil has a tendency to revert back to its original pH level if you do not amend.

ok great. i knew some of these products did change the pH but didn't know how to gauge A/S. I have my readings from yesterday so i will do that, keep a log and test every week or so. Since i did this yesterday, how long will it take for this area to change? If i do my test next week will it already have the new pH, or will it take a couple weeks ?

If in SC, I assume your soil is already on the acidic side. So you are not necessarily using this to lower pH dramatically but only as it applies to the hydrangea coloring. And the 1/2-1 cup application is intended to be an annual dosage. It's the 1 tbsp to gallon of water method that is applied monthly.

But you really do need to determine what your current soil pH is so you know if you do need to apply more frequently.

ETA: the soil pH will not change that fast (4-6 weeks) You do not need to test any sooner than once a month. And I doubt I would even do it that frequently as you have used the higher, annual dosage.

FWIW, my soil pH is naturally 6.3. I only apply the AS to the hydrangeas that are directly adjacent to any concrete. Others planted elsewhere in the garden flower blue all on their own - no AS required.

This process is slower than watching paint dry so do not expect quick changes. Hee hee hee! ;o) No need to test weekly; might be way expensive to do that. I do it monthly or every two months.

Obviously, to measure changes in blooms (meaning the shade of blue or purple or pink), you may need to do something like I do which is to take pictures of the blooms every year in order to compare. I only do this to one shrub which blooms in Spring and late in the Fall so I get pics twice a year -hopefully- using the same camera and I try to take the pics under the same conditions (8am and sunny). While not perfect, it makes it easy to compare from one month to another or year to year.

Ohh my mistake, i re-read Luis's post. I thought you said every week, you had said every month ! now it makes more sense. I have my pH written down at home, I think it was 6.5/6.6 but i remember last year i had lots of mixed blooms, and more importantly i have three hydrangeas that are along a walkway next to all concrete so i really wanted to help them. They are the bloomstruck so i want good purples out of that plant. That clarifies a lot up, i guess ill go back to waiting for spring and new blooms !

Can Soil Acidifier be use in June? We just planted some Hydrangeas.

You can apply it any time you want. But it will have little to no impact on flower color for this season.

You are supposed to use it all year long forever. If you stop applying it per the label recommendations, the soil will slowly revert back to its original soil pH. There are times of course, when one cannot apply it... like in cold zones during winter, when the soil freezes.... so just resume applying it when the soil thaws.

Thanks for all the help here I live in Va. My blue hydrangeas were dark purple . My neighbors said they but baking soda on theirs a the blooms were beautiful but mine are now turning green and not so blue what can I do to correct this ?

Baking soda won't do a thing to incease the blue coloration of Hydrangea macrophylla, so feel free to toss that idea in the can :-) The pigmentation of most blue or pink colored hydrangeas is determined by the amount of aluminum available in the soil. Adequately acidic soil will release AL freely, resulting in blue flowers - more neutral to alkaline soil pH will tie up aluminum or make it less available, resulting in pinker flowers. Baking soda will tend to neutralize soil pH or push to the alkaline side of the scale (if applied in quantity) so will prevent the bluing rather than enhance it.

Blue hydrangeas that are more on purple side are generally indicating that the soil is not sufficiently acidic or that aluminum levels may be low. Using aluminum sulphate, aka hydrangea bluing, helps to both acidify the soil (sulphur) and provide adequate levels of AL, should that be low. The greening you are seeing is very common to the aging of hydrangea flowers, regardless what their original color was. Just part of the natural color changes they go through as the flowers age.

The purple color should last a few weeks, maybe up to a month before the bloom starts getting old and begins to show greens and sometimes splotches with various shades of pink (darker or lighter). Some of my blooms have started changing to brown now.

I add aluminum sulfate throughout the year to the one shrub that I am trying to turn blue. However, it gets stuck in purple-ish colors. The one it got this year was rather interesting. In the mornings and in the afternoons, the blooms looked purple. At around 7-8pm, when the sun goes down, the shaded shrub had a tinge of blue when I looked at it. Mind you, I am currently trying to keep the blooms purple instead of turning blue. I started trying to get them blue but decided I liked the purples and have not increased the levels of aluminum sulfate any more.

Is holly tone acidified the same thing as aluminum sulfate ?

No, they are 2 completely different products. HollyTone is an organic fertilizer that has some slight acidifying effects due to the cottonseed meal it contains as well as some sulfated forms of other plant nutrients. It is not aluminum sulfate, which is an inorganic compound. HollyTone contains no aluminum.

In alkaline soils, if you want to change colors, you will need to use either (1) aluminum sulfate or (2) if you know that your soil is alkaline but has aluminum then you can also use garden sulfur. A soil test can tell you if your soil is alkaline and if it contains aluminum. Or you can just amend with garden Sulfur about two months before blooms appear and observe if blooms change color. If you do not want to do a soil test then just use aluminum sulfate to eliminate the guesswork of whether you have aluminum or not..

When you amend the soil with garden Sulfur or aluminum sulfate, the products lower the soil pH and make the soil more acidic. Continue amending per label directions as the soil tends to revert back to its original state if you quit amending. This happens slowly though but, just be aware so you do not forget to amend.

I used AS, to turn my Hydrangeas blue, do I still need to used a fertilizer like holly tone to feed my Hydrangeas?. By using only the AS, are they getting the proper food?, Thanks

No. Aluminum sulfate is not really a fertilizer as it provides none of the three primary nutrients required by all plants. At best, it is just a soil amendment :-)

Something like Holly Tone would be a good fertilizer. But hydrangeas don't require a lot of fertilizer. I just mulch mine with compost and that seems to provide all that is necessary. Even just cottonseed meal works fine.

Once your plant has become established in the garden (say, after about 1-3 years), you can switch to mulch only (or mulch + organic compost or composted manure). But if your soil is sandy or has mineral deficiencies, you may need to continue (for long periods if the soil sandy or until the deficiencies are no more).