What Is Budburst?

Spring signals the start of budburst in vineyards around Australia and is a significant step towards the success of the next vintage. But what is budburst, and why is it a vital part of the winemaking process?

We caught up with four Hunter Valley wine experts to answer these questions.

Andrew Margan

Winemaker and Owner, Margan Wines

Andrew Margan of Margan Wines.

Q. How do you describe bud burst?

In the biological sense, the budburst is when at least 80 % of the vine’s buds have their leaves out of the bud. This usually occurs in the Hunter Valley around the first two weeks of September, although every variety differs, and the aspect of every block has an effect. In an emotional sense, for those of us who grow grapes, it is the start of the new season that brings enormous expectation and hope for what the year will bring!

Q. Why is bud burst an essential stage for producers?

Budburst is the first sign of the next vintages crop, and whilst you can cut into buds to see how much fruit they are carrying, it is only once the buds have all shot (or not) that you can know how much fruit is on the vine.

Q. What is bud burst looking like in your vineyards?

The buds of early Chardonnay are starting to pop out, but the actual bud burst has yet to arrive. There is plenty of subsoil moisture, and we had really healthy vines last year, so it augers well for this season. I like to live with hope and not expectation.

Learn More About Margan Wines

Liz Riley

Owner, Vitibit and Viticulturist, Scarborough Wines

Liz Riley of Scarborough Wines.

Q. What measures do you take to ensure bud burst happens smoothly?

The winter season is when we prepare the vines for the new season with pruning to regulate bud numbers and set the vines up for the new season with good spacing, structure, and crop load. We time pruning to be not too early (to avoid any frost risk) and not too late (to see a delayed harvest), and if it has been a dry autumn and winter, we would apply irrigation in July and August to fill the soil profile with moisture.

This tends to support a more even budburst and better crop outcomes at harvest. Less glamorous, we also use this winter period for machinery, trellis, irrigation repairs, and maintenance to ensure the new season runs smoothly.

Q. Can you comment on how budburst is going in the Hunter?

The vines have started to pop in the Hunter with an early spring break and above-average temperatures, so we are already looking down the barrel of an early harvest for Vintage 2025! Chardonnay and Verdelho on the red and black soils, which warm up earlier than the pale soils, were first out of the blocks, and these will be followed by Pinot Noir, Shiraz and Semillon in the coming week or two.

Learn More About Scarborough Wines

Andrew Thomas

Winemaker and Owner, Thomas Wines

Andrew Thomas of Andrew Thomas Wines.

Q. What is bud burst?

Towards the end of the growing season in autumn, vines lose their leaves. As temperature decreases, vines undergo several processes in preparation for ‘shutting down’ for the colder months. During winter, we prune our vines in preparation for the following growing season. As the daily temperature rises, the individual buds on each cane of the vine start to swell and eventually burst with the start of the new season’s shoot growth.

Q. Why is budburst an essential stage for producers?

Budburst is an exciting time for vignerons and winemakers as it signals that the next vintage is coming. The vineyards must be well prepared and pruned for the new season’s growth and ideally have adequate groundwater to sustain the latest activity. For Thomas Wines, the first day of spring is also the time that we release our new suite of Semillons from the previous harvest and our next vintage instalment of our Cellar Reserve Braemore Semillon.

Q. What is budburst looking like in your vineyards?

We only grow Semillon and Shiraz which are generally slightly later to spring back to life. We have had some reasonable winter rainfall which has provided some good moisture levels in the root zone, so it’s looking like a perfect start to the new growing season.

Learn More About Andrew Thomas Wines

Mike De Iuliis

Winemaker and Owner, De Iuliis Wines

Mike De Iuliis of De Iuliis Wines.

Q. At De Iuliis Wines, how do you ensure budburst happens smoothly?

Apart from ensuring all vineyards are pruned and ready to go before budburst, there is not a lot we can do. Budburst is purely dictated to us by the change in seasons and the warm weather to increase soil temperatures, and the vines know it’s time to go!