I want to plant Rhodiola Rosea and it requires calcareous soil. I have experience growing it in clay soil and it was very easy. But my soil here is sandy and acidic. I can add the organic matter, lime, but it is still not same as clay based soil - too light, too fast draining. I would like to create a permanent area with the type of soil that fits better to Rhodiola Rosea, but so far I am not sure how to achieve it.
It doesn’t have to be very large, 4X4’ for the beginning. What I do not want is yearly addition of the lime - it will become a very expensive project if I will have to make soil test every year. I am not even opposing to drive somewhere and get some clay(trade for compost, anyone? 
), I am just not sure if it will really improve the conditions for RR with all the sand below created area. RR is growing on rocky soil in the wild, may be it make sense to to dig a whole and put few inches of rocks on the bottom , then mix clay with native soil and some crashed shells or marble dust? Please share your ideas!
I recommend looking into limestone dust, or ag lime. It shouldn’t need to be applied often. I do not recommend marble, alkalinity would not be as available as limestone. Marble is a metamorphic form of limestone if I recall correctly. Also consider bags of optisorb around the plants, that may be all you need.
It seems like this species likes rocky or otherwise poorly weathered souls, especially with it being distributed so much in the Canadian shield and along the Urals. I’m surprised then that it does well with clay soil. For getting a rocky soil, coarse gravel is always an affordable and easily available option.
And yeah, coarser types of limestone will release much slower and are often cheaper.
It seems to me like you would not need to change the soil much https://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex13054/$file/188_20-2.pdf?OpenElement
I think that you should add organic matter, and get something like this
Maybe even add some gravel as well.
My opinion is to pick your battles. I went through this with blueberries in the reverse situation. i wanted acidic soil and had calcareous. Focus on an above ground bin and fill it with clay soil. It is easier to grow in a bin or grow bag than start trying to ammend a larger area.
I don’t understand the source of your concern. What is your soils pH and where are you trying to take it?
Any plant can grow in the coarsest of soil or hydroponics wouldn’t be a thing. If water retention is a problem, compost amends it- it is even better than clay at increasing plant available water without risking drainage issues as much. Shredded or chipped natural wood mulches also are more than adequate to compensate for the disadvantages of a porous, course soil in terms of water and nutrient retention.
I’m just not sure what it is you are worried about. Have you done a simple search of the issues of growing this plant? Do you know if any part of the following is incorrect? These days I start all my searches by going to Chat and have found it to be the quickest source of generally reliable info. Not and end-all, but an excellent starting point. This info suggests that clay soils may be the enemy of this plant as it is for many others.
Rhodiola rosea, also known as golden root, is a hardy perennial herbaceous plant that thrives in cold, mountainous regions. It is valued for its adaptogenic properties and medicinal uses. Here are its special growing requirements:
1. Climate and Hardiness
- Hardiness Zones: Prefers USDA Zones 3–7.
- Cold-Tolerant: Requires a cold, alpine-like climate and can survive harsh winters.
- Summer Temperatures: Thrives in cool summers; prolonged high heat can stress the plant.
2. Light Requirements
- Full Sun to Partial Shade: Prefers full sun in cooler climates but can benefit from partial shade in hotter regions.
3. Soil Requirements
- Well-Draining Soil: Needs sandy, rocky, or loamy soil to prevent root rot.
- pH Range: Slightly acidic to neutral soil (pH 5.5–7.0) is ideal.
- Nutrient Levels: Does not require highly fertile soil; nutrient-poor, well-drained conditions mimic its native alpine environments.
4. Watering
- Low to Moderate Water Needs: Overwatering is a major threat. Ensure soil dries out between waterings.
- Drought Tolerance: Established plants are drought-tolerant.
5. Spacing and Planting
- Spacing: Space plants 12–18 inches apart to allow for airflow and growth.
- Planting Depth: Rhizomes should be planted shallowly, with buds just below the soil surface.
6. Temperature and Frost
- Cold Stratification: Seeds require cold stratification (4–6 weeks at 32–41°F) to germinate.
- Frost Hardiness: Mature plants can withstand severe frosts.
7. Propagation
- Seeds: Germination is slow and can be tricky. Cold stratification improves success.
- Division: Dividing rhizomes in early spring or fall is a more reliable propagation method.
8. Pests and Diseases
- Generally Resistant: Few pests bother Rhodiola, but watch for root rot in poorly drained soils.
- Weed Control: Keep the area weed-free to avoid competition for nutrients.
9. Harvesting and Maintenance
- Root Harvesting: Typically harvested after 3–5 years when the roots are large and rich in active compounds.
- Pruning: Dead or yellowing foliage can be removed to maintain plant health.
10. Special Considerations
- Alpine Simulation: Mimicking its native alpine conditions (e.g., cold winters, well-draining rocky soil) improves growth.
This is a very strange for me. In both ( and only) sources where I found the live plants they talking about calcareous soil. I don’t think it is only about PH. It is more about calcium without raising PH that much. What I know for sure, that it grew very well in my mother’s garden with clay and acidic soil, but with very high calcium content. Nobody did the test, but the spring water had so much calcium that you couldn’t use it without filtering, it created hard deposit right after one boiling and you couldn’t drink it. And second piece of information I know for sure, that it died in my garden, when I planted it in the ground hole filled with mix of compost, peat moss, perlite and store bought topsoil. Back there I didn’t have natural soil, just construction fill with 2 inches of topsoil on top.
If they just need calcium add some gypsum. It’s cheap and it dissolves a lot faster than limestone/calcite and its not hazardous like lime
Gypsum will raise calcium levels in the soil without affecting PH.
If you have river or creek bluffs in your area… (limestone rock bluffs like we have here) the soil along the bottom of the bluff will be loaded with limestone rock chips.
Get a few 5 gal buckets…
TNHunter
A bag of gypsum sounds like the solution you are searching for. I use it for my tomatoes too. I still stand by optisorb as a good option; it will hold moisture as well as drain. You may already have granite and other materials similar to the native environment for this plant.
Up in New England granite and other metamorphic rock may be more common than the sedimentary rocks like limestone. I’m not super familiar with the particular area though.
That’s right, not much of natural limestone here, mostly granite.
How much of it do you think is needed for an area 4X4 if I am planning to make artificial soil as deep as 18 inches?
I’ve been making my living in soil for half a century, and I’ve not heard of plants that especially require HIGH calcium unrelated to pH. I do not trust the employees at most nurseries to even be gardeners, let alone informed ones, unless they grow their own plants. See if you can find a single source in a search that claims this species requires a high calcium content in the soil in order to grow it. I tried.
I understand the need for gypsum in some soils that are low in available calcium but not acidic. I also understand the danger of having a small area of imported soil- if it is more colloidal (finer textured) than existing soil, drainage can be damaged. If Chat is correct, your species is particularly susceptible in soils without good drainage.
Many in this forum have expressed a dislike for using AI to obtain answers suggesting that they can go there to get there answers themselves. However, if you are not well versed in a subject you probably will not be that good at asking the right questions to quickly find your answers.
How often are soils naturally formed with high pH but low available calcium and where in the U.S. does this occur.
ChatGPT said:
ChatGPT
Soils with high pH but low available calcium are relatively uncommon but can occur under specific conditions. These soils are usually found in arid or semi-arid regions where precipitation is insufficient to leach soluble salts, leading to the accumulation of other alkaline cations like sodium or magnesium that can displace calcium.
Conditions Leading to High pH but Low Available Calcium:
- Sodium-Dominated Soils (Sodic Soils)
- High levels of exchangeable sodium raise pH, often above 8.5, but sodium displaces calcium on soil colloids, reducing its availability.
- Sodic soils are typically found in areas with poor drainage or high evaporation rates, leading to salt accumulation.
- Magnesium-Dominated Soils
- Soils rich in magnesium can also exhibit high pH if magnesium carbonate (MgCO₃) dominates, especially in areas with dolomitic parent material. Magnesium may inhibit calcium availability due to ionic competition.
- Carbonate and Bicarbonate Presence
- High levels of bicarbonates (HCO₃⁻) in irrigation water or soil can form calcium carbonate (CaCO₃) precipitates, locking up calcium in unavailable forms.
- Low Organic Matter
- In arid soils with low organic matter, the lack of complexing agents such as organic acids can exacerbate calcium unavailability despite high pH.
Locations in the U.S. with High pH, Low Calcium Soils:
- Southwestern States (e.g., Arizona, New Mexico, Nevada)
- Sodic and saline soils are common in these regions, where evaporation exceeds precipitation. Sodium accumulation and limited calcium availability are frequent problems.
- Great Plains (e.g., parts of Texas, Oklahoma, Kansas)
- Certain areas in this region feature soils with high sodium or magnesium content, leading to poor calcium availability.
- Intermountain West (e.g., Utah, Idaho, Montana)
- Areas with poorly drained soils and carbonate-rich parent materials often show high pH but limited plant-available calcium.
- California’s Central Valley
- Irrigated soils with saline or sodic conditions can develop high pH and low calcium availability, especially where bicarbonates are prevalent in irrigation water.
Management Strategies:
- Gypsum (Calcium Sulfate): Adds calcium without raising pH, improving soil structure and displacing sodium.
- Leaching with Water: Helps flush excess sodium but requires good drainage.
- Organic Amendments: Increase soil organic matter to improve calcium availability.
I would add that improvement in structure by adding Gypsum only occurs in sodic soils, but until I ask Chat that question specifically, I will not be sure it is true. It is what I remember reading in a soil text book 35 years ago. I have the book on my shelf, but it would take me much longer to look up any facts in it than simply typing out a question to Chat and the chances are that the answer would be more current.
Now check this out-
Shouldn’t you include the caveat that soil structure improvement from adding gypsum only occurs in sodic soils and is not helpful in improving structure in typical poor drainage soils high in clay
ChatGPT said:
ChatGPT
Memory updated
You’re absolutely right! Gypsum’s ability to improve soil structure is effective primarily in sodic soils because it displaces sodium, which is the cause of poor structure in those soils. In contrast, gypsum does not improve the structure of poorly drained soils with high clay content unless sodium is the problem.
I’ll adjust the statement to clarify:
- Gypsum (Calcium Sulfate): Adds calcium without raising pH and improves soil structure only in sodic soils by displacing sodium. It does not address structural issues in non-sodic, clay-heavy soils with poor drainage.
Would you like further clarification or additions to this topic?
4o
You said:
I only hope you will modify your response to the original question so people don’t think that gypsum is some kind of cure all for soils with “poor structure”.
ChatGPT said:
ChatGPT
Absolutely—thank you for pointing that out. I’ll revise the original response to ensure clarity on gypsum’s limitations:
That is fine information, but I don’t think it relates to my case. I am not asking why soil with high PH may have low calcium. Instead my question is, how to make acidic soil to have high calcium content without raising PH.
Gypsum
Which is covered simply with the gypsum cure but the question remains whether this species has a particularly high requirement for calcium as was suggested to you by nursery workers.
I found no indication for that so I wondered if you lived in an area that has a high pH but low availability of calcium, which is the only reason I could think of for the recommendations.
I like to know how and why as that is the only way to be able to reliably make management decisions in general. How may only apply to a single situation- why can be widely adapated for the solution to a wide range of problems.
Im going to put this out here again as one who has tampered with soil, dont start it just use containers above ground and do what you want in those. You can grow beautiful blueberries here just not in this dirt. Im not a big fan of acidic soil in general though for blueberries it is amazing!
Thats how I grow blueberries here. 10-20 gallon landscape pots filled with peat moss and some watersorb. Works well