Best method of planting perennials (hydrangea) - native or amended soil?


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Hello!

I am planting six Nantucket Blue hydrangeas in Dallas, TX (8a). They will all receive dappled shade throughout the day courtesy of being under two large live oak trees. I hope the dappled shade will protect them enough to survive our hot summers. I will have drip irrigation set up for them, and I already purchased the 5-gallon plants from a local nursery but have not put them in their holes yet.

There's a lot of clay (alkaline) in Dallas, but it's not especially dominant or heavy in the beds that I'm putting the hydrangeas in. There are lots and lots of worms, so that's good, and there is a good amount of clay, but there's also some more workable soil too. The holes I dug are 10-12 inches deep, and are 3 feet wide and 4, 6, and 8 feet long. In the 4 ft and 6 ft holes I'm planting one hydrangea each, and in the 8 ft holes I'm planting two.

I see some conflicting advice regarding backfilling holes with NATIVE vs AMENDED soil for shrubs. Gardeners' World says in their show to backfill with only the NATIVE soil you took out so roots are encouraged to spread and avoid the issue of creating pot-like conditions where water might drown them, especially in clay soil. Neil Sperry, a local source of expert advice, says for hydrangeas to completely replace dug-out soil with a mix of half peat moss and half pine bark and mound it about a foot above grade as well, to discourage wet feet. Neil's recommendation seems too light on food for the plants, right? I also found thistlewoodfarms.com which has a page for hydrangeas in Texas and I am tempted to follow their recommendation, which is to replace the native soil with peat moss + potting soil + pine mulch.

Summary of what I could use help with:
1. Should I backfill with the unamended native soil, or should I get rid of the native soil and put in an amended mix?
2. If amended is better, what recipe should I use?
3. I want a mix of blue and pink blooms. In Dallas, I'm told that by default the blooms will be pink once they reach our alkaline clay soil, and I'll have to work hard to achieve blue blooms. My current plan (unless you advise me otherwise) is to backfill with peat moss + azalea soil + pine mulch + sulphur, and add aluminum sulfate on a schedule, if needed, to get blue blooms. I figure eventually some of the blooms will turn pink due to our alkaline natural soil around the beds and our alkaline tap water I'll be using to water them. What advice do you have to try for multi-color blooms?

Thank you all SO MUCH! I'm hoping these plants will help my wife and I be reminded of the amazing hydrangeas in New England!
 
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Wow, sounds like you gave much thought to this. good for you. my zone is 6, so my only experience, I get hydrangeas that can deal with harsh winters, my property is mostly dappled shade. When I plant any new shrub. I dig the hole 1 and 1/2 wider and deeper than the pot. Keeping the native soil to the side. I use 1/2 native soil and half a good rich garden soil, and fill in around the pot with that. I mulch a good 2 to 3 inches on top of that, pulling the mulch away from the base of the shrub, give it a good watering. And that is it. One year, I put in a hillside of heath and heathers, the company said they like manure and peat mixed in with the clay soil, so the rotatiller and I had fun with the bags mixing and blending. As far as color change for your hydrangeas, I have 13 varieties, that is something I don't deal with, what color they are, they are. Most of mine are cream. I actually enjoy finding the unique shapes of the flowers. There is a company that carries lots of hydrangeas up in Washington State, of which I had shipped in a few, and personally selected from them, maybe they can help you also with your question, their name is Heronswood, or maybe Heronwood. (no "S").
 
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LGY

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lol the potting soil vs native soil was what I have researched for a whole year, but for a Japanese maple rather than hydrangea. The theory is the same though, it all depends how big a hole you are digging to change the soil. If you dig just a regular hole with potting soil, when the root grow out and search for water, it will be happy for a short time, until it literally hit the wall of native soil. Then the root just stay within the small space and not happy and might even be root bound. If you are ready to dig a swimming poll size for a plant, then amending soil without native is the way to go. Otherwise just do half-half or at least one third.

I recently bought a compact hydrangea myself and trying to learn how to take care of it myself. I was told to use this fertilizer as starter for “amending” plus bonus it’s a fertilizer. https://www.ebstone.org/product/azalea-camellia-gardenia-food/

P.S. I didn’t dig a swimming pool.


Hello!

I am planting six Nantucket Blue hydrangeas in Dallas, TX (8a). They will all receive dappled shade throughout the day courtesy of being under two large live oak trees. I hope the dappled shade will protect them enough to survive our hot summers. I will have drip irrigation set up for them, and I already purchased the 5-gallon plants from a local nursery but have not put them in their holes yet.

There's a lot of clay (alkaline) in Dallas, but it's not especially dominant or heavy in the beds that I'm putting the hydrangeas in. There are lots and lots of worms, so that's good, and there is a good amount of clay, but there's also some more workable soil too. The holes I dug are 10-12 inches deep, and are 3 feet wide and 4, 6, and 8 feet long. In the 4 ft and 6 ft holes I'm planting one hydrangea each, and in the 8 ft holes I'm planting two.

I see some conflicting advice regarding backfilling holes with NATIVE vs AMENDED soil for shrubs. Gardeners' World says in their show to backfill with only the NATIVE soil you took out so roots are encouraged to spread and avoid the issue of creating pot-like conditions where water might drown them, especially in clay soil. Neil Sperry, a local source of expert advice, says for hydrangeas to completely replace dug-out soil with a mix of half peat moss and half pine bark and mound it about a foot above grade as well, to discourage wet feet. Neil's recommendation seems too light on food for the plants, right? I also found thistlewoodfarms.com which has a page for hydrangeas in Texas and I am tempted to follow their recommendation, which is to replace the native soil with peat moss + potting soil + pine mulch.

Summary of what I could use help with:
1. Should I backfill with the unamended native soil, or should I get rid of the native soil and put in an amended mix?
2. If amended is better, what recipe should I use?
3. I want a mix of blue and pink blooms. In Dallas, I'm told that by default the blooms will be pink once they reach our alkaline clay soil, and I'll have to work hard to achieve blue blooms. My current plan (unless you advise me otherwise) is to backfill with peat moss + azalea soil + pine mulch + sulphur, and add aluminum sulfate on a schedule, if needed, to get blue blooms. I figure eventually some of the blooms will turn pink due to our alkaline natural soil around the beds and our alkaline tap water I'll be using to water them. What advice do you have to try for multi-color blooms?

Thank you all SO MUCH! I'm hoping these plants will help my wife and I be reminded of the amazing hydrangeas in New England!
 
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