Budbreak occurs when new buds begin to open.
These buds may open to become leaves, flowers, or twigs, but timing is everything when it comes to budbreak. Open too soon and tender shoots freeze. Open too late there isn’t enough time for flowers, fruit, or other new growth to mature. Very often, when to fertilize or treat for pests and diseases is determined by budbreak.
What causes budbreak?
Budbreak (or bud break) occurs in response to a combination of factors. Lengthening days and warmer temperatures are the two main stimulants, but plant variety, genetics, age, and health are big factors, too. As soil temperatures rise, osmosis causes water to be drawn upward into the plant through the xylem. This water is carrying minerals, sugars, organic acids, and hormones from the roots. Those hormones stimulate the buds to ‘break’ open.
Fertilizing & budbreak
Many fertilizer instructions will say “apply fertilizer two weeks after budbreak”. This is because plants are using a lot of energy and nutrients in creating all this new plant tissue. Roots store the initial nutrients used, but young leaves may not be able to produce enough energy. Fertilizing in the early part of the process provides the nutrients needed for the best health and maximum production.
Pruning & budbreak
Most fruit and nut tree pruning is done while trees are dormant (apricot and cherry the only exceptions in the Bay Area, due to Eutypa Dieback). Pruning before budbreak makes a lot of sense. Bottom line: there’s no sense allowing plants to put effort into twigs and buds that are going to be pruned out anyway.
Budbreak & disease analysis
Erratic or reduced budbreak can indicate a number of different problems. Monitoring plants in mid- and late-winter and early spring can help you determine problem areas, such as:
Budbreak as a production indicator
When and how budbreak occurs can give you a good idea of what’s ahead. Early budbreak normally indicates earlier flowering and fruiting. Reduced bud break means less fruit thinning later in the season. Uneven budbreak may cause the harvest to be spread out over a longer period.
How to promote healthy budbreak
Healthy plants are generally able to recover from temperature, water, pest, and disease stresses well enough to generate a good crop of buds each spring. Maintaining that good health requires proper pruning, irrigation, feeding, and regularly monitoring for pests and diseases.
Commercially, substances are applied to stimulate simultaneous budbreak, for easier management. They also use fans and overhead sprinklers to protect against frost damage. This isn't realistic for the home orchardist. If your buds break too soon, as my almond tree did this year (in late January!), there isn't much you can do, except enjoy the shade this summer and hope for a better crop next year.
I hope this information inspires you to grow more of your own food. You can ask your garden questions on my Home page.