soil preparation for rhododendrons in a non-acidic soil

mikelata

Hi all,

A few years ago, I was starting with gardening, I did not know anything about soil types and plant needs, and I planted azaleas and a camellia plant in non-acidic soil. The plants went sad and I fixed them using iron fertiliser. The camelia is now healthy and flowers beautifully, but the azalea plants never really took off and only randomly flower every year. They are still the same size

I want to plant Rhododendrons now. What soil preparation would you advice me to do now, so I don't repeat the same mistakes?

Thanks

wildwillow

I'm going to annoy you by saying work with the soil you have and forget plants which need acid soils. They will never really thrive. You need to drive around West Cork and Kerry and see those plants in their preferred soil to see how poorly they do otherwise.

There are thousands of plants which will be beautiful in your garden without going to extraordinary lengths to accommodate them. I speak as someone who started gardening on acid soils but am on alkaline soil for years. I have a wonderful mix of shrubs and flowers, lots of colour and scent.

But if you persist you will do better growing in large pots where you can supply acid soil. This may mean using lots of peat, which isn't encouraged.

Using rainwater will help as it should be more neutral than mains or well water.

Responder XY

rhodoodendron is a horrible invasive species. Be glad it doesn't grow in your garden and move on to grow something more appropriate.

magicbastarder

rhododendron ponticum is a horrible invasive species, and is illegal for sale here IIRC.

there are hundreds of other rhododendrons which aren't invasive and it's almost certain the OP is not talking about planting ponticum.

mikelata

Thanks for your replies

The original motivation for the garden was creating a Japanese-influenced garden, which explains the initial choice of those plants. I completely understand the advice to work with the soil you have. It makes lots of sense

Not sure how it is technically called, but the rhododendron type I was thinking gives you lovely red flowers. I hope it was not a ponticum

I might need to think of another red-flowering shrub that is happy in my soil

Thanks

looksee

Ponticum is the purple flower rhododendron, you will not obtain it unless you go into the mountains and dig one up.

You can plant red flower shrubs, chaenomeles (flowering quince) has bright red or orange flowers and is spectacular in spring. Weigela also can be got in red (also pink) and is easy and reliable. Flowering current is another easy one, more pink than red but get the right one and you can have lovely red (edible) berries in autumn. You can find red hydrangeas and they are great value for easy flowers. And of course roses. Don't forget cherry blossoms for winter and spring.

Also remember that there are lots of plants with red leaves and stems - a red stem dogwood can be spectacular in spring with red branches and brilliant acid green leaves - keep it well pruned. Pieris Forest Flame is another one that has startling red new leaves that stay red for a good bit of the season, it really prefers a slightly neutral to acid soil but is pretty easy going. Red robin if kept well under control also has good red leaves in spring. You can get Japanese Acer for spots that are a bit sheltered from wind, some are red and others turn red in autumn, they have a very Japanese garden look about them (funny that 😀) They also have a bit of a preference for slight acid but I have grown them in a lime soil garden no problem. Sweet Gum will give you glorious orange red leaves in Autumn.

mikelata

I went yesterday to the National botanic gardens to compare my acid loving plants agains against theirs…

I could not find any azalea but they had lots of camellia japonica, and a huge range of rhododendron types.

You can see the difference between the camellia plants in the pictures. If you get closer to my camelia you find lots of brown leaves, even thought I gave it some iron recently

mikelata

You can roughly see the state of my 2 azaleas in the previous message images. They have not grown in 5 years. I am tempted to remove them altogether and plant them in a pot with the right soil. I am equally tempted to do the same with the camellia and rethink that spot

I have another azalea in the garden too, which is doing slightly better in terms of colour , but it never grew either

My idea is to have evergreen plants with occasional red flowers, which is the reason why I chose a camellia, azaleas and i was targeting rhododendrons. This is why I did not add any hygrendrias, that even though they are beautiful, they are not evergreen. I already have a beautiful Japanese maple tree but I will check @looksee suggestions above.

Thanks a lot for your great suggestions, advice and recommendation everybody!

The Continental Op

OP the RHS have some good advice https://www.rhs.org.uk/soil-composts-mulches/acidifying-soil , which I mention as no one has said anything about the traditional soil acidify Sulphur.

mikelata

The issue is that the plants are already planted and according to the article “Applied to the surface it can take years for the acidity to be changed at root depth”

Something I should do is to measure PH levels, which I have not done yet.

Cheers

looksee

If you really want to stick with camellias and azaleas you could wait until next early winter (November-ish), dig up the plants, keep the rootball on them and keep them damp (cover with something to stop them drying out, plastic sheet for example). Dig out the soil in the beds to a depth of about 18 - 24 inches, then fill with ericaceous compost. Over-fill as the surface will settle. If you could get hold of some acid soil that would be better again, but probably difficult. Gently wash the soil off the roots of the plants preferably with rain water, then carefully replant the (now) bare root shrubs. Or put in new ones - probably a better idea. If you put in new ones they will be in ericaceous compost so just plant as they come out of the pot.

I still tend to the opinion that its better to use what you have and plant accordingly, but otherwise that is a possibility.

mikelata

Yes, I think you are right.

My current thinking is replanting the camellias/azaleas in pots with the right soil and putting them somewhere else.

Then, rethinking what evergreen/shrubs to plant in place of them that suits my garden soil and fits the Japanese influence intention

Cheers

MacDanger

I saw part of a gardening programme sometime last year where they were talking to a woman who has loads of rhododendrons (almost certain it was rhododendrons, she was talking about crossing-breeding them and what not) in a location where the soil isn't ideal and apparently she uses the prunings from the plants as mulch underneath to help acidify the soil - might be worth trying. If yours aren't growing too well though, you may not have much in the way of prunings

macraignil

Another suggestion for an evergreen with red flowers would be Crinodendron hookerianum (Chilean Lantern tree) but that is another one that prefers acid soil and I have lost some here as they may not be cold hardy enough for my north facing hill top garden. Embothrium coccineum( Chilean fire bush) might be another option. Lots of shrubs as well have nice red berries with Cotoneaster franchetii, Holly and pyracantha potential options for that. Red currant berries are also nice in colour but the flowers are not very much to look at.

The rhododendron in the garden here get the cut up pieces of old Christmas tree as mulch in the hope that will make the soil acidity suit them a bit better but it is slightly acidic anyway and they have been doing well since planting with nothing done to change the soil pH.

Happy gardening!

standardg60

https://www.boards.ie/discussion/comment/120462417#Comment_120462417

Before you do anything drastic give the beds a good feed of general purpose granular fertilizer, none of the plants look particularly healthy, you might be surprised with the results in a couple of months.

The Continental Op

https://www.boards.ie/discussion/comment/120474231#Comment_120474231

I'd go one further and suggest a feed with Sequestered Iron.

standardg60

https://www.boards.ie/discussion/comment/120474314#Comment_120474314

Op has already applied iron. General yellowing would suggest iron deficiency, whereas yellowing between the veins and/or edges is more often than not just lack of nutrient.

The Continental Op

https://www.boards.ie/discussion/comment/120474534#Comment_120474534

As long as the Iron they used was in a form the plants could use.

mikelata

https://www.boards.ie/discussion/comment/120474231#Comment_120474231

I am gonna do that this weekend...

If I then transplant them to a pot, how easy is to buy acidic soil? I was looking in a couple of places and I could not find any

looksee

Look for ericaceous compost in most garden centres or hardware shops.

celticbhoy27

Just flicked through thread so forgive me if already mentioned. There's a species of rhododendron that are lime tolerant. Inkharo is their name

mikelata

hi all,

Just to experiment and see if an acidic miracle happened, I tried to change the pH level by applying Sulphur to one azalea and Aluminium Sulphate to the other two. I bought a little pH test device, but the pH levels didn't move at all, and I started this process about 2 months ago.

I think I'm gonna start transplanting the azaleas to pots with ericaceous compost. Is this a good time of the year to do so?

Having said that, the Camellia might not be thriving, but at the same time, it's doing way better than the 3 azaleas. Every time I give the plant iron, it reacts positively and promptly. Once I remove the azaleas, I'll have more room in the ground to fertilize or acidify from a deeper spot and improve the soil around it. So, I'm wondering whether I should give that plan a go.

Any advice would be great. Thanks a lot for your help and advice so far in this thread!

looksee

Is it a good time of year - not really, give it another few months, into November.

My experience with plants that do not thrive (or have been too long in a pot) has been that generally they don't really improve all that much regardless of what you do to the conditions they are in. You don't really have anything to lose by potting them, but don't be too dismayed if they don't do much. As I said earlier, I think you are throwing money away trying to change the PH of your soil and planting acid loving plants again, but that's just my opinion.

mikelata

Thanks for the advice! I’m going to give it a few months and not get my hopes up too much for the azaleas.

Your suggestion about not planting more acid-loving plants in the wrong soil makes sense. Just to clarify, I already have a camelia in that soil, and it seems to be doing better than the azaleas – maybe it’s more adaptable? So I’m thinking of focusing on making the camelia happy in the current soil before deciding I need to go for the same plan B as with the azaleas

Cheers

looksee

It depends on what kind of Camelia it is. It its one of the common ones that flowers in early spring with darkish pink flowers, they seem to be much more accepting of alkaline soil than any of the varieties.

Just looked at the pics, the first one with dark green leaves looks like the one I was referring to, the other one looks a bit sad.

mikelata

Thanks @looksee

A different but related question. I have a few ferns and a couple of fatsia plants in the garden, that I would like to move to a different location of the the garden. All of them are doing great, but we did some work in the garden and I was wondering about transplanting them to a new location in the garden.

I guess I should also wait for a few months until the weather has fully cooled down. Any other consideration I should keep in mind?

Thanks for the advice!

looksee

Fatsia shouldn't be a problem, depending on how big and manageable they are. Most ferns will move provided you get a good root ball on them and move to a similar environment - don't take a fern that is thriving in damp shade and stick it in the sun for example, and vice versa. Do it later in the year though. Don't despair of them for at least 12 months if they appear to die off, many of them are very good at coming back from apparently dead.

mikelata

The context is that when I planted the ferns a few years ago I was really ignorant of their growth properties. So, as a result, I have a couple of ferns that are buried in between other taller plants.

I was thinking of moving them 2m away from their current location, so they will be getting similar conditions: soil quality, humidity, etc. so I'd assume that they will adapt well to the new location, especially if I manage to take as much of the root ball as possible to minimize transplant shock.

Now that the idea is in my head, it's hard to wait until November! :-)

Thanks!

mikelata

I was told yesterday that , in cold climates like Ireland, it would be better to wait until spring to transplant the azaleas. Would you agree, or would you still transplant in November as planned?

thanks

Jim_Hodge

https://www.boards.ie/discussion/comment/121208516#Comment_121208516

If you're taking a decent root-ball do it when it suits you. I'd personally do it in spring as November soil can be very wet and nothings going to happen until spring anyway.

mikelata

https://www.boards.ie/discussion/comment/121209119#Comment_121209119

Thanks, would it make sense to do it now, and relocate the newly potted Azaleas indoors if the leaves begin to yellow/decay?

Weedy Gonzalez

I too love rhododendrons so don't be put off by people who consider all rhododendron invasive as it just isn't true.

I find they grow well in neutral to acidic soils. However, they can be grown in any soil conditions buy doing a bit of groundwork prior to planting. Dig a very large rectangular hole 4ft by 4ft. Buy 2 large bags of peat moss. Using a screwdriver pierce about 20 holes on one side of bag. Place this bag into the hole with drainage holes on the bottom. Then cut a 2 foot square window from the top side. On top of that add another large bale of compost with a two foot window cut and placed directly in line with the existing bag in the hole. Top bale should be at ground level. Cut another window from the top and plant the rhododendron. Mulch with bark chip to cover any visible plastic. Your rhododendron will live happily in this altered environment for many years.