The almond was originally native to the Middle East and Southeast Asia. They have since spread around the world. Almonds grow primarily in California in the United States.
Almonds are unusual in that the fruit of the almond is a drupe, consisting of a husk and then a hard outer shell protecting the inner nut. Almonds are not true nuts — they are related to peaches and plums and are considered a stone fruit. The almond is a deciduous tree that can reach heights of 33 feet.
Oddly enough, wild almonds are bitter and toxic. Crushing and chewing the fruit causes deadly prussic acid and cyanide to form in the fruit. As few as fifty wild, or bitter, almonds can be fatal. Sweet almonds, or domesticated almonds, are not toxic.
Almonds are one of the few fruits that can be grown successfully from seed. They are not grafted, so seeds breed true. Most people, however, buy young almond trees to plant.
Almonds prefer well drained, deep sandy soil. They will develop root rot in heavy clay soils or where drainage is not good. Almond trees prefer a climate with mild winters with no severe spring frosts and warm, relatively dry summer.
Plant trees by digging a hole deep enough for the tree to be planted at the level the tree was in the pot. Make the hole large enough around to spread the roots out in it. Fill with the soil you took out of the hole. Putting compost, peat moss, or potting soil in the hole will cause the roots to circle the tree and eventually girdle it. Water the tree in. Almonds need regular irrigation to produce a good crop..
Almonds will not pollinate themselves. You always have to plant two trees of compatible species to ensure pollination. Almonds are pollinated by bees. In the United States, fully half of all hives in the US are transported to California in February to pollinate the almond crop. As such, almonds have disproportionately suffered from colony collapse disorder in bees. There are efforts underway to develop self-pollinating almond trees with desirable fruit.
Almonds are mature at three years and begin bearing. They are five or six years old before they bear a full crop. Almonds need considerable care during the year to thrive and produce a good nut crop. In the winter, they must be pruned to open up the inside of the tree so air can circulate. In addition, dead or damaged branches should be removed then. Spray trees with dormant oil to kill peach twig borer, San Jose scale, and mite eggs. Remove all old nuts from the tree and ground and destroy them to prevent pests from overwintering in them.
In the spring, fertilize the trees with two pounds of urea per mature tree, spread around the tree and watered in. Trees need to be watered daily with drip irrigation. If this is not possible, sprinkler irrigate every 1-3 weeks after winter rains have fallen and lay down 2-3 inches of water per irrigation. Trees in very sandy soil need to be watered more often to keep them from drying out while trees on sandy loam can be watered less often.
In the summer, continue irrigating as in the spring. Fertilize again just prior to the last irrigation before harvest. Nuts are ready for harvest after the hulls split and the shell is dry and brown. Separate hulls from nuts and discard. Freeze in-shell nuts for 1-2 weeks to kill resident worms. Store in plastic bags to prevent reinfestation.
In the fall post harvest season, spray trees with copper during or after leaf fall to prevent leaf shot fungus in the spring. Make sure the spray is done before the winter rains begin.