Hi I just planted two Encore azaleas (Autumn Sangria). The tag says that they recommend acidic soil. I put down some organic topsoil that we'd purchased from our local nursery, but I'm not sure how acidic it is. I looked at some potting soil I'd purchased and that didn't look any better.
Is there a top soil/potting soil that you would recommend for these? I also need some acidic soil for an azalea that I transplanted today (I used the organic topsoil on it for now) and for two other existing azaleas in front of the house. (These three are all standard variety azaleas, not the ever-blooming kind.)
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Garden Spider
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The easiest way to make soil acidic is to add peat to whatever soil you use. (This is a bit controversial, as peat bogs are being dug up all over the world, and I may take some flak for suggesting this). However, you don't need much peat; I buy a bale of it, and it lasts several years. Just drop several handfuls into the planting hole, mix it in with the soil.
If you are planting these next to the house, and you have a cement or concrete block foundation, lime will leach out of the cement, and you will need more peat in the planting hole.
To keep the soil acidic, spread coffee grounds around the plant. Starbucks has a program where people can collect their used coffee grounds; other coffee shops might let you do this, too.
Pine or fir needles will also acidify the soil, if you have a source of those--apply them as a mulch any time of year.
If you are planting these next to the house, and you have a cement or concrete block foundation, lime will leach out of the cement, and you will need more peat in the planting hole.
To keep the soil acidic, spread coffee grounds around the plant. Starbucks has a program where people can collect their used coffee grounds; other coffee shops might let you do this, too.
Pine or fir needles will also acidify the soil, if you have a source of those--apply them as a mulch any time of year.
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MaineDesigner
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This is one of those situations where you really have to know where you are starting from - get a soil test. A pH test is simple, you can do it at home or send it out to a lab if you want more complete results. If you have to move pH a significant amount, e.g. if your soil measures 7.8, the best solution is to add sulfur. Depending on the starting pH, the pH you are trying to achieve and the type of soil you have you'll find the correct amount of sulfur to use on the bag or container. Iron sulfate is faster acting but has less long term effect. I do not recommend products like Miracid for this application. The caveat is that if you are one of the parts of the U.S. where the parent rock is limestone the buffering capacity of the soil may be so great that maintaining a low pH is a constant battle.
You should check the pH of your water source too as it may be at least slightly alkaline in many parts of the U.S. (either from private wells or urban systems).
If you need to lower your pH more than a few tenths peat moss, pine needles or coffee grounds are not an efficient way to get there. Peat moss itself is not sustainably harvested. Although Canada does have huge peat reserves harvesting it very adversely effects those ecosystems. It is a much over rated and over used soil amendment.
You should check the pH of your water source too as it may be at least slightly alkaline in many parts of the U.S. (either from private wells or urban systems).
If you need to lower your pH more than a few tenths peat moss, pine needles or coffee grounds are not an efficient way to get there. Peat moss itself is not sustainably harvested. Although Canada does have huge peat reserves harvesting it very adversely effects those ecosystems. It is a much over rated and over used soil amendment.
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Garden Spider
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MaineDesigner, thanks for your input. I should have suggested getting the soil tested; I live in an area where the soil is naturally acid, and a few handfuls of peat in the planting hole does the trick. Of course, that is not the case everywhere.
In my experience, the soil can't be too acid for azaleas and rhododendrons; have you also found that to be true?
In my experience, the soil can't be too acid for azaleas and rhododendrons; have you also found that to be true?
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MaineDesigner
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Maine generally has acidic soils too so it usually isn't a problem here but in the Upper Midwest soil pH was often in the 7.2 - 8.0 range and there it was difficult to maintain a pH below 7.0 - the best solution was to build a raise bed with fresh soil.
I haven't tested the limits but I suspect soil can be too acidic even for most ericaceous plants - I would think that point is probably somewhere around 4.0 to 4.5 (roughly the pH of tomato juice). Lowbush blueberries actually do well in that pH so there are a few exceptions but that is extremely acidic soil.
I haven't tested the limits but I suspect soil can be too acidic even for most ericaceous plants - I would think that point is probably somewhere around 4.0 to 4.5 (roughly the pH of tomato juice). Lowbush blueberries actually do well in that pH so there are a few exceptions but that is extremely acidic soil.