Succulent Garden Soil Issues
by Peter Gooller
(Chula Vista, California, USA)
I need help with my Succulent Garden. My soil appears to have a lot of clay. I think I may need to add Gypsum...
Hi Peter, generally, clay soil is good for succulents, however, what it needs more than gypsum is most likely gravel. I would mix some smallish gravel, like pea gravel size, into the top part of the soil, which unless it dries into concrete will open it up and prevent the pore spaces from clogging.
You haven't said if you are growing your plants in raised beds, but this might be a good idea so that the clay doesn't just get completely waterlogged and rot the roots of your plants.
In some cases the most successful succulent gardens are built with rock walls, which ensures the perfect drainage that these plants need. The soil can be nutrient poor, but absolutely must have the ability to drain.
I've also had good success with adding dolomite lime to the soil for succulents, especially in places where it's had decades of pine needles falling on it, or in your example, the soil is predominantly clay. This helps the plants by adjusting the acidity of the soil into something more close to neutral.
Be aware that Echeveria dislike lime, so if you're growing those, avoid putting dolomite lime on the garden.
Hope this helps a bit, if you have any more questions, ask me in the comments.