Definition - What does Bud mean?
A bud on a grapevine is the area that fosters new growth and undergoes many changes throughout the seasons each year. There are three different types of buds, primary, secondary and tertiary on the vine that present themselves as the need arises.
Buds are an integral part of the vine because it is where the shoot, tendril or leaves start to grow. At the bud, we also see the vine make “decisions” to grow out of a bud or keep it dormant depending on what the vine needs for optimal growth.
WineFrog explains Bud
The primary bud on the vine is actually the bud that will produce a shoot, flower or fruit but contains the two other buds within it to be used as needed. Most of the time, the primary bud is developed the year prior to growing and influenced by environmental conditions around the vine. If conditions are good the primary bud will grow the next year after bud break.
If conditions are not favorable, the buds may stay dormant or the secondary and tertiary buds will grow in place of the primary. The secondary bud functions as a backup to the primary bud, which grows if the primary bud has been damaged by climate, pests or disease. The secondary bud can produce comparable yields and growth to the primary bud but in most cases, only the primary bud develops into flowering clusters and fruit during the growing season. If the vine is in extreme distress the tertiary bud will act as a safeguard and continue to grow but typically will not produce flowers or fruit. Under harsh conditions or in cases of extreme pruning, all three buds will produce shoots, flowers and fruits but this is a rare occurrence.