The Dirt Gardener's Column for May 8

Q. I’m planning on reducing the size of my lawn and replacing it with edibles like citrus and pomegranates. How will the plants ever get the food with a four-inch layer of mulch and does it need to be removed every time I want to feed?

A. Today, all of the granular fertilizers are water soluble, so they dissolve in water. All mulches are porous, allowing water to pass through it. When we typically fertilize, the fertilizer is applied around the drip line of plants, scratched into the soil surface and then watered in. With mulched plants, there is no difference. The fertilizer is scattered over the mulch. When you water, the fertilizer dissolves and the mixture of water and nutrients percolates into the root zone. Another method of feeding would be to foliar feed; here the nutrients are absorbed into the plant through the leaves. If you have plastic sheeting under the mulch, you would concentrate the fertilizer around the area were the cut out for each plant is located. This is not necessary with landscape fabric as it is also porous. Personally, I don’t recommend either. A four-inch layer of mulch should do a very good job suffocating the weeds. Plastic and landscape fabric are a short-term fix for weed control, as the unwanted vegetation will eventually grow in the mulch itself. Bark is an organic material, it decomposes as the large particles become smaller and smaller. After a season or two the four-inch layer of mulch, becomes a one-inch layer of very fine material. Hence, it needs to be refreshed and the plastic or fabric gets in the way. Weed seeds are an annual problem as they’re air-borne from the wild grasses that grow in the open spaces and can travel a great distance. In non-irrigated areas, they germinate with the winter rains or within four to six weeks in irrigated locations. So, the expectation that the area is now weed free forever and ever is very flawed. It is just a matter of time before they return. You can prevent the weed seeds from germinating in the mulch by applying the pre-emergent herbicide Impede from Monterey Lawn and Garden. It can be applied right over the top of rooted plants without damaging them. You next must water the herbicide in to establish the chemical barrier, which last for about six months. A couple of final thoughts, before mulching install a watering basin around each plant and make sure the crown of the plants are not being slowly buried by the decomposing mulch.

Q. We have an eight to ten inch tall columnar cactus that has toppled over in its pot. It appears to have rotted at the base. Is there anyway, we can possibly save it?

A. With most plants, there isn’t much you can do; however, cactus is unique so I wouldn’t give up on it yet. I’d trim away the soft, rotten tissue and then replant it into fresh Cactus Mix. There is a better than average chance that it will reestablish itself

by Buzz Bertolero, CCNP