Grape vine flowers appears as soon as the newly formed clusters starts “opening”.  What I mean by opening is explained in the following three images.

Grape Vine Flowers

Picture 1:  The grape vine flowers are not visible yet because it is covered with flower caps, so in other words; what looks like berries in this picture, isn’t actually berries!  This is still early days in the growing season, and as soon as the temperature rises, the grape vine flowers will become visible.  However, at this stage,  you will notice that the “berries” are compact, small and soft.

Picture 2:  The grape vine flowers are still not visible in this picture, because it is the early stage of grape vine flowering.  The grape vine flowers start to develop underneath the flower caps and soon the flower caps will turn yellow/brown and crack open.  This in an important stage of berry development and mild temperatures, enough water, calm wind conditions and no rain, is the ideal climate for perfect grape vine flowers.

Picture 3:  In this picture you can clearly see the grape vine flowers, with pollen carries and stigma.  If you enlarge the pictures of the grape vine flowers, you will clearly see the flower caps that cracked open, revealing the grape vine flowers and pollen carries.

Grape Vine Flowers

Most wild grape vines you find in the woods are male or female plants and need cross pollination to produce grapes.  Nowadays, 99% of the commercially grown grapes  are self-pollinated and no cross-pollination is needed.

Another question I often receive about grape vine flowers, is about cross-pollination of different varieties.  Some grape growers are concerned that if they plant two or more varieties in the same vineyard, that the grape vines will produce grapes that are not “variety-true”.

If you grow grape vines of different varieties in one vineyard, and all of them are self-pollinated, then you will not have any trouble with cross-pollination.  The vines will only accept pollen from it’s own pollen carries.

Have a look at the picture and email from Eric below – I will reply below his email.

Danie,

Can you tell me what’s wrong with my berries. This is the second year for my vines (they were probably 2 years old when I planted them. All the clusters are low on the vines and many of the berries in the clusters are dwindling away (see picture). Can you tell me what my problem is? I’m in a coastal region of Southern California.

Thanks for your help

Eric

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Hello grape growers.

Today we will be looking at the grape vine sex – and NO, this is not what most of you thought it would be!

Grape vines, like many other fruit types, are self-pollinated where the female and male parts needed for pollination are present on the same plant. If you can recall your biology lessons from school, you will remember that there are certain things that need to be present for a flower to be a perfect flower.

Female part (pistillate):

This is the central part of the flower and consist of basically 3 things

• The stigma – the soft tissue at the end of the pistillate, where pollen is accumulated
• The style – a tube where through the pollen will move to reach the ovary
• The ovary – the place where the fertilisation takes place

When you look at the a grape flower, you will notice the pollen-carriers (stamina), these are the male parts of the flower.

Male part (stamen):

This is the outer part of the flower, just underneath the petal and consist of basically 2 things

• The anther – the place where pollen is produced
• The filament – a long stem that supports the anther at it’s tip

For your grape vine to pollinate, all of these parts must be present in a grape flower. Certain wild grape varieties, do not have male or female parts on their flowers and is called dioecian plants. Cross pollination needs to take place for these grape vines to bear fruit. Most of the commercial grape varieties used these day are self-pollinated and do not need cross-pollination in order to bear fruit.

During pollination, the pollen from the anther of the male part of the flower, falls on the stigma of the female part, and grows down the style until it reaches the ovary, where it will penetrate the wall of the ovary so fertilisation can take place.

Dramatic climate conditions (wind, rain, and extreme cold and extreme heat) can have a negative influence on how well pollination will take place. Mild, sunny weather is ideal.

During poor pollination weather, you will notice that grape clusters will be straggly and very loose, with not many berries on the clusters and the opposite happens with too good pollination weather – the grape clusters is too compact, deforming and damaging nearby berries. This is often the starting point for secondary infection (botrytis or grey rot).

There isn’t much you can do about to straggling grape clusters, but in the case of compact bunches, you can thin out the bunches by removing berries by hand or blunt scissors. DO NOT work with scissors in a bunch after the berries softened – you will damage the surrounding berries and this will be were infection can start. Try to thin out the bunches when berries are still green (the size of small peas)

Have a look at this pictures to see what a male, female and perfect flower looks like.

male flower

female flower

perfect flower

Have a grape day!

Danie

“The Grape Guy”

PS: For more proven grape growing techniques, get your copy of the Complete Grape Growers Guide today!