Fertilize Grapes in Mid Spring

Q. I have two grape vines, one white and one red. When and how should I fertilize these grape plants?

A. All grapes whether they are red, white or black are fertilized a couple of weeks before new growth begins. Your visual key to apply fertilizer is the swelling of buds for new growth. This gets the fertilizer in place and ready to be pulled into the plant by the plant roots when the plant is ready to grow. If you haven’t already done it, fertilize it now.

This is a wine grape just showing new growth in mid spring, about the first or second week of March in the Las Vegas Valley. It is not too late to apply fertilizer...if it needs it.

            The fertilizer, whether you are using conventional granular, compost or organic types like fish emulsion should be in contact with wet soil after it is applied. This means if your fertilizer is “fluffy”, like compost, any surface mulch is raked back, and the compost applied to the soil surface where the soil will get wet. Then rake the woodchips back and cover the soil again. Granular or liquid fertilizers like fish emulsion may be applied to the surface of  mulch and washed through it to the irrigated area of the soil using a hose. Granular or liquid fertilizers are a little easier to apply than compost.

            Granular fertilizers used for established lawns work well on young vines if the soil is covered with woodchips. Fertilizers used for tomatoes or roses work well on mature vines. If you planted your grapevine with a good quality compost mixed in the backfill you may not need any fertilizer the first two or three years. Look at the grapevine and judge for yourself. If it had strong growth last year then apply a half application of fertilizer. If the vine is weak and not growing well, apply a full amount of fertilizer.

Grapes perform much better with a surface layer of woodchip mulch applied to the soil surface in the desert.

            Grapes don’t grow well when surrounded by rock. Your grapes will perform better with less stress. In our desert soils, grapes prefer soil covered with woodchips. If your grapes are surrounded by rock, I would strongly encourage you to rake it back, spread an inch of compost on the soil surface and cover the soil, at least six feet in diameter around the vine, with 4 inches of woodchips. Grapes struggle enough in our hot deserts without adding the extra stress from surface rock.

            Apply fertilizers about 18 inches from the trunk or main stem of established vines so they don’t do any damage.