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| Herbs in Shallow Soil |
Answered by: Inge Poot
Question from: Susan Pinder
Posted on: May 5, 1999
I have a question about growing herbs. I discovered the area I was going to plant in has a stone or concrete slab under it giving a soil depth of about 6 to 10 inches. Is this enough depth? The soil is rich and full of worms. I don’t think anything has been planted there in a long time.
As you have probably already noticed, the area with the impermeable base dries out faster than the rest of the garden. The soil there cannot wick up more water from deeper strata. Therefore this area will act more like a pot and since herbs can be grown in pots, planting herbs there is no problem - if you water when it gets dry. Many herbs will actually have a stronger taste since they will get more stresses due to heating and drying of the more shallow root ball. However these stresses are no different from those experienced by plants growing on a layer of soil over bedrock.
You might wish to not use the area for shrubs and trees, since confining their roots this way may stunt their growth and make them less winter hardy- but maybe you like bonsai trees!
Fertilizing regularely with a dilute fertilizer will also reduce the impact of the non-availability of sub-soil.