Hibiscus forum: Hardy Hibiscus soil

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Name: Cole Williams
Colorado (Zone 5a)
Apr 8, 2020 11:28 AM CST
Hi everyone, I have a luna red hardy hibiscus (Hibiscus moscheutos) that I planted a couple years ago, this is my third season with it. I live in a zone 5 in Colorado.

Now I understand they are normally slow to start growing back in the spring, but mine is EXTRA slow because I made the mistake of planting it directly in my clay soil, no amendments at all. This was before I took any sort of gardening seriously. I probably had three or four blooms total last season, probably because it took so long to grow. Sad.

I don't think I can really dig up the soil very much to amend, can I? Would humic acid help? Top dress with compost?

Thanks in advance for your advice.
Name: Ken
Winston-Salem, NC (Zone 7b)
Daylilies & hardy hibiscus
May 1, 2020 6:46 AM CST
I would dig it out, add LOTS of compost (leaf compost works well, or finely ground pine mulch, or peat moss, or even bagged compost from a big box stores).

I guess you could add some bagged "garden soil" if you want. The most important thing I can think of is DON'T DIG WET CLAY. It will clump or peel and harden into balls or sheets. Plus, yuck.

Try to rough up the edges and bottom of the hole (a spading fork is perfect, or the pointed edge of a shovel). Youre trying to break the clay so roots have cracks or holes to grow into. You're also trying to avoid creating a sheer-sided clay "bowl".

Mix your amendments in with the existing clay, and replant your hibiscus. I guess up there maybe you plant it a bit deeper, but if it's too deep it'll take even longer to emerge in spring.

Anyone else have ideas? I mean, I suppose you could just let it be. They're pretty tough plants and eventually it'll grow.
Hardy hibiscus are a hobby, but daylilies are an obsession.

May 21, 2020 10:22 AM CST
Just be patient. I have two H. moscheutos planted directly in clay soil and the only amendment I did when planting them was to add some manure at the bottom of the dig. They are doing fine but I am in Zone 7b, a lot warmer than Colorado.
For this season you can try adding some organic mulch (hay, homemade compost, chipped twigs and leaves... they all work fine) to keep the soil warmer and start improving the texture of it and using a liquid fertilizer to help flowers a bit. A PK (no nitrogen) fertilizer is the best to help stimulate blooming and is easy to find.

After the plant has gone to rest in the Fall you can dig it out: that's the beautiful thing about H. moscheutos. Since it goes completely dormant you can dig it out, move it around, improve the soil etc without harming the plant.
These are really great plants and I love them.
I am just another white boy who thinks he can play the Blues.

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