Growers contended with patchy frost in spring and extreme heat in summer but Heathcote Winery winemaker Rachel Pavlou said the crop had potential to be better than last year's.

"There's a lot of flavour and really good colour in the shiraz due to the cold nights we’ve been having," she said.

Mrs Pavlou said the winery had picked some of the grapes from its 10-hectare Newlans Lane vineyard, seven kilometres south of Heathcote. 

"What we’ve seen so far I think is at least as good, if not better than last year," she said.

"We are very pleased, especially considering the heat we've had."

Mrs Pavlou said hot days earlier in the year meant waiting to get the right flavour from the vines.

"The vines shut down and stop producing during the extreme heat, which hit a bit later than previous years. We had 11 days over 40 degrees in January and five days over 45," she said.

The last grapes to be picked will be shiraz from the four-hectare Slaughterhouse Paddock, just north of Heathcote.

Heathcote suffered patchy frost in spring but a frost detection and spray system saved most of the crop.

"Mother nature throws a lot of interesting things at us and every year is quite different," Mrs Pavlou said.

Water Wheel Vineyards owner Peter Cumming said frost and hot weather were also the main challenges at Bridgewater this year.

"We’ve got three vineyards but frost is a very fickle thing," Mr Cumming said.

"One vineyard was devastated, one was touched a bit, and the one in between was untouched. 

Mr Cumming, whose vineyards cover about 95 hectares, said hot weather in January had delayed the vintage by almost two weeks.

"Due to global warning we pick more than a month earlier in Bridgewater than we did 20 years ago," he said.

"This year was different and the reason was ironically because of the hot periods in January. "

Mr Cumming said it would be difficult to beat last year's vintage.

"For whatever reason 2013 was a fantastic year and it’s unlikely that this year will be as good," he said.

Another challenge for the Bridgwater winegrower is water quality. He irrigates his crop from the Loddon River.

"With global warming we get less rain and the water quality in the river we irrigate from declines," Mr Cumming  said. 

"If water quality is down, so is your yield and quality."

Big Hill Vineyard managing director Jo Barclay said November frost also hit the Ravenswood area hard. 

"We won’t have shiraz or cabernet sauvignon this year but we are hoping for good results from the merlot," she said.

"We have the same challenges as any other farmers. It’s no different to growing wheat or anything else."