Unmistakable reminders of fall, bountiful crops of nuts can come fromyour garden almost as easily as from the grocery store. Threenuts–macadamia, European hazelnut, and pistachio–have faraway originsbut thrive in the West; they also share an exotic appeal born ofscarcity. If you want to grow these nuts, see the map at far right tofind where each of them produces most reliably. But if you’reinclined, experiment: macadamias grow in Berkeley and pistachios inChula Vista. Harvests are irregular, but it’s fun to try to beatthe odds. Planting time for each nut varies: bare-root time in winterfor hazelnuts, spring for pistachios, almost any time for macadamias.Hazelnuts: at home in western Oregon and Washington In the Northwest, this delicious European nut became known as”filbert” to avoid confusion with the much smaller wildhazelnuts that abound in the region. But now, because importedhazelnuts are readily available, Northwest-grown ones use the same name.
Left itself, European hazelnut (Corylus avellana) develops into a15- to 20-foot-high vase- or fountain-shaped deciduous shrub; to developa single-trunked small tree, you can prune regularly to remove suckersaround its base. Flowers, or catkins, appear in midwinter, lasting intospring. Most varieties are hardy to about -5[deg.], but flowers aredamaged below 15[deg.]. All hazelnuts require cross-pollination. Thisis why varieties are considered as pairs, each either a “maincrop” or “pollenizer.
” The ‘Barcelona’ and’Daviana’ combination prevails commercially, although it isgradually being replaced by the superior ‘Ennis’ and’Butler’. Other pairs are ‘Du Chilly’ (pollenized by’Daviana’) ‘Hall’s Giant’ (‘Butler’or ‘Daviana’), and ‘Royal’ (‘Daviana’). Bare-root hazelnuts are available at the nursery in January orFebruary.
Production of nuts begins after 3 or 4 years; after 10 years,each tree typically yields 10 pounds of nuts. Collect ones that fall,mid-September to November. Dry unshelled nuts on a screen-bottomed tray, in an onion sack, ona sunny window-sill, or in a food dehydrator. Try to keep temperaturebelow 100[deg.], with plenty of air circulation. Nuts are fully drywhen their internal color changes from white to cream.
After drying,they keep for several weeks at room temperature; roasting enhancesflavor but shortens storage (one week at room temperature). Water when ground shows signs of drying; fertilize young trees withnitrogen if growth is slow, leaf size relatively small, and leaf colorpale. Protect the exposed trunk from sunburn with white latex paint orcommercial tree wrap. Aphids can be troublesome; they produce honeydew that drips–onereason many gardeners avoid planting hazelnuts near patios. Wash aphidsaway with a strong spray of water (perhaps mixed with mild dishwashingsoap).
The filbertworm often ruins nuts by tunneling throughthem–spray sevin in early and late July, and harvest and dry nutspromptly. Pistachio: from the Middle East to the Central Valley,Southwest deserts Looking quite unlike its relative, California’s familiarChinese pistache, the nut-bearing pistachio (Pistacia vera) is asmaller, somewhat less ornamental deciduous tree with slightly larger,dark green leaves. Within about 10 years, it grows 25 feet high and aswide. The picture at bottom right shows its rose-colored husks; ivorynuts are inside. Pistachios grow where summers are long, hot, and dry, and wherewinters are moderately cold: to induce dormancy necessary for good nutproduction, trees need at least 1,000 hours between 32[deg.] and45[deg.].
A dormant pistachio easily survives 15[deg.], but late frostsin spring–as well as strong winds and wet weather–can injure blossomsand interfere with pollination. You’ll need a male tree–‘Peters’–to pollinate atthe most 12 nut-bearing female tree–‘Kerman’–before flowerscan set fruit. If space is limited, graft a male branch onto a femaletree. Plant pistachios in spring after frost danger passes. They beginbearing after three or four years; a mature tree produces 40 to 50pounds of nuts a year. Harvest begins when hulls loosen, mid-Septemberto mid-October. (Growers shake trees so nuts fall onto a catching frameor canvas sheet.
) Remove hulls, then dry in the sun or air until crispto the bite. Refrigerated nuts keep several years. Prune young pistachios when dormant to develop four or five mainbranches, the first ones 3 to 4 feet from the ground. Once a basicstructure is established, prune only to remove interfering or brokenbranches. Water frequently during nut development–June throughAugust–stopping in mid- to late August to promote ripening.
Resumeregular watering after harvest. Fertilize in spring, usingapproximately 2 pounds of 10-percent nitrogen fertilizer per tree. Pistachios tolerate alkaline and saline soil, as long as it is welldrained. Trees are susceptible to verticillium wilt, a soilbornedisease favored by hot, dry soils; it’s most prevalent where cottonhas grown. Try to get trees on P. integerrima rootstock–the mostresistant.
Macadamia: coastal Southern California, Hawaii Native to eastern Australia, this 20- to 30-foot evergreen tree ishandsome enough to be planted as an ornamental, regardless of any cropit might bear. Glossy, leathery leaves make a dense canopy; white tored flowers appear late winter to early spring. By fall, clusters ofhard-shelled nuts hang like oversize grapes. Rough-shell macadamia (M. tetraphylla and hybrids) thrives inCalifornia but not in Hawaii. Nut husks are rough, leaves are spined(new leaves are usually tinged red ro pink), and flowers are light greenor cream to brown.
Nuts ripen October to January. ‘Cate’ isthe best known. Smooth-shell macadamia (M. integrifolia) is grown in Hawaii, rarelyin California. Nut husks and leaves are smooth, and flowers are white.Most nuts ripen July to November in Hawaii, November to March inCalifornia. Many varieties are grown in Hawaii; some California growersare experimenting with ‘James’, ‘Keaau’,’Pahala’, and ‘Smooth Queen’. The hybrid’Beaumont’ combines characteristics of both types; it is themost productive macadamia for home gardens.
Flowers are pink to red andvery fragrant; leaves are just slightly toothed. It’s fastgrowingand more wind-resistant than the others. Deep, fertile, well-drained soils are best, although trees tolerateheavy clay and slow drainage better than avocado trees, which grow inthe same climatic conditions. (Macadamia is virtually immune to avocadoroot rot, making it an excellent replacement tree where avocadossuccumbed to that disease.) Established macadamias tolerate some drought but perform best withconsistent watering. For best growth, fertilize regularly but alwayslightly (some growers favor fish emulsion).
Insect pests are rarely aproblem. Prune young trees to shape; encourage a strong central leaderwith wide-angled branch crotches beginning 3 to 4 feet from the ground. Macadamia trees usually begin producing in three to five years.Plant anytime except midsummer and midwinter. Fully grown after 10years, most trees produce 30 to 60 pounds of in-shell nuts a year.Harvest nuts that fall to the ground, beginning in September.Don’t shake the tree–it causes immature nuts to fall.
Husks areusually open at harvest time; if not, remove they dry. The nut insideis hard to crack, even with a hammer. Special macadamia nutcrackers areavailable from Gold Crown Macadamia Assoc., Box 235, Fallbrook, Calif.
In a dry, shady location, air-dry hulled nuts on hardware-clothtrays for two to three weeks, then dry further in circulating warm air,as in a food dehydrator.