Suzanne also recommends soaking a handful of ground oyster shells in the seasoned water. This helps increase soil alkalinity, something cape primroses like.
Many pet stores sell ground oyster shells as a digestive supplement for birds.
When the water in the can is gone, she leaves the shells in it and just refills with water and fertilizer. Just as with African violets, getting the foliage wet will cause spotting and scorching. Suzanne always waters her plants from the bottom so that she doesn't damage the leaves. She also lets the soil dry out before watering again. To start new plants, remove a leaf at the plant's base and cut down each side of the center rib, as shown in illustration at right.