The 2015 Vintage is on its way…
….Well at least it is in its early stages. At present the vines are coming into flower and the weather during flowering will determine fruit set – put simply this is the number of flowers that develop into a grape.
Many of the guests I take on a tour around the Marlborough wineries are surprised that grape vines have flowers but it is a pretty standard rule for most fruiting plants that fruit follow on from flowers. In general no flowers means no fruit. There are a few exceptions to that, the one I am most familiar with is the fig tree in my back garden which develops fruit without the need for flowers.
So back to the grapes. You can see in the picture on the left the flower buds. Each of the little green blobs is a flower bud. The green covering – called the cap – is made of fused flower petals and rather than opening as most flowers do the cap simply falls off. Grapes rely on the wind to spread their pollen so although the flowers do have a faint delicate small there is no need for coloured petals and nectar to attract insects.
Once the cap falls off the pollen and ovary are exposed. Pollen needs to be transferred from the anther to the stigma for pollination to occur. At this time of the year the weather is critical. For the few days of flowering we are hoping for warm,dry and breezy weather so that the pollen is carried on the wind. Very cold wet weather can lead to low pollination rates, which means poor fruit set and lots of empty spaces in the bunch.
The two photos are of chardonnay grapes at Na Clachan on 29 November 2014. Each grape variety tends to flower at a slightly different time so you can get perfect weather whilst one is in flower and very poor weather when another is in flower. As an indication today we have had rain and very cold wind as a southerly batters its way up the country. Tomorrow it is forecast to reach 23C.
It is easy to see which flowers are developing into fruit as the ovary quickly begins to swell.
So all that needs to happen before Christmas so that the individual grapes have plenty of time to fill out and ripen.
There is a lot going on before we can get that wine into your glass. Join Na Clachan on a Marlborough wine tour and find out more