Growing Almonds: From Tree to Table – A Complete Guide to Nature’s Nutritious Nuts

Standards for the market

In California, all almonds sold to the public are pasteurized to reduce risks of salmonella.

The United States Department of Agriculture (USDA) maintains strict standards and grades for California almonds covering everything from defects to discoloration.The top grades, such as US Fancy, Extra No. 1 and US No. 1 (Supreme) require strong visual appeal with low levels of chips or scratches (5-15%), only 1% of kernels should be split or broken and the sample should contain less than 0.05% ‘foreign’ material.

Levels of dust also need to be kept to a minimum in all grades at <0.1%, and harvest management is critical in this respect. Grades such as US No. 1 Whole and Broken, or US No. 1 Pieces, accept higher levels of chips or scratches and broken nuts. Nut size and levels of other defects are less critical and these nuts are sold at a lower price for use in food ingredient manufacturing.

Pruning encourages consistent, high yields of good quality nuts. It is also used to shape the tree to ensure it has the right pattern of branches to carry the load and allow good light penetration and air circulation as well as to remove diseased or weak branches and those that grow into the working space between the tree rows.

Pruning young trees helps them develop a desirable shape and branch structure. As nut trees become larger, unless it is needed to allow better light penetration, pruning is usually limited to removing dead or damaged branches. Common practice is to prune the tree branches at planting. This results in several shoots competing for the position of the new leader or main trunk. As a consequence, when the new shoots are 8 – 12 inches long, growers select the strongest and straightest as the leader and pinch out the growing tips of the competing shoots.

In late winter or early spring each year, the lower branches are shortened. If any of the lower branches grow vigorously during the growing season, the practice is to pinch out the growing point. As the tree grows taller, these lower branches can be cut right back. Leaving the lower branches on the young tree, aids early growth by maintaining its photosynthetic area; it also provides shade for the trunk during the growing season. Eventually all branches arising from the trunk within 3 feet of the ground are removed. This facilitates mowing and other cultural practices.

Hazelnuts, which are commonly multi-stemmed, need more aggressive pruning to thin out the smaller and weaker suckers each spring, cutting them off at ground level.

Alternate bearing – where a high crop load in one year is often followed by a low yield in the next year – is an issue in most nut tree species.

The reasons for alternate bearing are not fully understood, but it is assumed that parameters such as hormonal imbalances, or the competition for carbohydrates or nutrients during flower bud differentiation/fruit development, are to blame. Long term studies of flower and fruit production in almonds show that individual spurs alternate between years in which flowers and fruits are produced, and years in which only leaves are produced. As a result, if the majority of spurs on a tree bear fruit in one year the tree will produce a greater than average crop and the following year most of the spurs will mainly produce leaves, resulting in a lower than average crop.

Researchers suggest that where high levels of a tree’s energy and nutrient resources are used in one year, there are fewer reserves available for the spring flush in the following crop. In an off-year, leaves have lower resource demands than the fruit and result in increased local storage for the following year when fruit are produced. In addition, the increased vegetative growth enables the tree to produce more carbohydrates for storage due to increased photosynthetic activity.

Because alternate bearing in almonds is largely due to competition on a spur level and there is a balance between fruiting and leaf-bearing spurs, annual fluctuations in yield are not as great as with some other nut species. Pistachio has perhaps the greatest tendency for alternate bearing. Research at UC Davis, California shows that after pollination, as pistachio fruit grows, new flower buds develop within the branch.

These growing fruits suppress developing flower buds that would otherwise flower and develop fruits in the next year. As a result, during years with greater than average fruit yields, the majority of developing flower buds are suppressed so that the following year only a few flowers and fruit are produced. This creates regular oscillations between high and low yields in alternating years, with more blank nuts produced in the off-year (Table 11).

Weather conditions that impact on flower and fruit development can exacerbate the alternate bearing tendency of individual trees or whole orchards. For example, a severe frost during bloom would kill developing flower tissue and result in a very low fruit set. Diseases that lead to early defoliation of the tree will also encourage alternate bearing. As a result of the low fruit set and reduced use of stored carbohydrates at each individual spur, the following year the majority of shoots will produce flowers and set fruit. If all spurs on a tree are synchronized to flower during the same year it will generate a whole tree, and even whole orchard, pattern of alternate bearing. This in part explains why groves across a complete region will have off- and on-years that correspond. Trials confirm this. In an off-year annual biomass growth declines, but shoot and leaf growth increases. As a result, in the off-year, while there is less nitrogen used by the tree, most of it is found in tree reserves. The research work also shows that in the on-year, more nutrients are found in the kernel compared to those in the lower yielding off-year.

Crop nutrition that ensures nutrient supplies are sufficient from the end of the dormancy, right through the season, can help to mitigate the effects of alternate bearing.

Growing Almond Trees – Flowering and Harvesting

FAQ

Are almonds considered a crop?

Maintaining the trees’ health during the almond growing season is essential for harvesting a plentiful crop.

Are almonds a tree crop so that farmers don t need?

Farmers do not need to replant trees every year to produce a crop of almonds. It takes at least five years after planting for trees to bear fruit. Several factors such as weather, disease, and long-term projections about price impact the supply of almonds available.

Are almonds a permanent crop?

Permanent crops are perennial trees or vines that are generally harvested every year and have 20+ year lifespans. Examples include almonds, apples, pistachios, olives, and wine grapes.

What zone do almond trees grow in?