Harvest time wine grape Brix readings from heavily frosted Central Coast vineyards will look more like Joseph’s multi-colored coat than a Hart Schaffner Marx Navy blazer.

The lack of uniform maturity is the only bet veteran grape grower Dana Merrill is willing to make on the outcome of this year’s wine grape crop in the wake of a bone-chilling spring frost.

Merrill manages 6,000 acres of wine grapes on the coast under the umbrella of Mesa Verde Management in Templeton, Calif. He has been farming on the coast for 40 years and has experienced nothing like the early April frost this year. Temperatures plummeted down to as low as 24 degrees and stayed there for an extraordinary nine hours or more in some areas. It fried tender, just emerged shoots so badly there may not even be a crop worth harvesting in some vineyards.

While Merrill is certain whatever crop is harvested will not be uniform, beyond that he is waiting and watching like other growers to see how the vines compensate for the killing frost. Crop loss estimates now range from 30 percent to as much as 90 percent. The county agricultural commissioner is documenting losses in anticipation of declaring a disaster.

San Luis Obispo County UC Cooperative Extension Viticulture Farm Advisor Mark Battany is advising anxious growers anxious to sit tight before trying salvage a crop by pruning off damaged wood or doing much else.

“It is going to be awhile before people know exactly what they have. I would be leery of a definitive early assessment at this point,” said Battany. “When we start seeing flower clusters and set, we’ll have a much better feel for the crop and damage.”

Battany admits damage is “pretty significant, but we really do not have numbers to put on it,” he added.

Battany is getting calls about what growers can do to salvage a crop. The first thing he reminds them is that frost season is not over. “The danger for frost continues until late May” and growers do not want to do anything that will jeopardize what crop they will make.