Unmistakable reminders of fall, bountiful crops of nuts can come from
your garden almost as easily as from the grocery store. Three
nuts–macadamia, European hazelnut, and pistachio–have faraway origins
but thrive in the West; they also share an exotic appeal born of
scarcity. If you want to grow these nuts, see the map at far right to
find where each of them produces most reliably. But if you’re
inclined, experiment: macadamias grow in Berkeley and pistachios in
Chula Vista. Harvests are irregular, but it’s fun to try to beat
the odds. Planting time for each nut varies: bare-root time in winter
for 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 wild
hazelnuts that abound in the region. But now, because imported
hazelnuts are readily available, Northwest-grown ones use the same name.
Left itself, European hazelnut (Corylus avellana) develops into a
15- to 20-foot-high vase- or fountain-shaped deciduous shrub; to develop
a single-trunked small tree, you can prune regularly to remove suckers
around its base. Flowers, or catkins, appear in midwinter, lasting into
spring. Most varieties are hardy to about -5[deg.], but flowers are
damaged below 15[deg.]. All hazelnuts require cross-pollination. This
is why varieties are considered as pairs, each either a “main
crop” or “pollenizer.” The ‘Barcelona’ and
‘Daviana’ combination prevails commercially, although it is
gradually 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 or
February. 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, on
a sunny window-sill, or in a food dehydrator. Try to keep temperature
below 100[deg.], with plenty of air circulation. Nuts are fully dry
when their internal color changes from white to cream. After drying,
they keep for several weeks at room temperature; roasting enhances
flavor but shortens storage (one week at room temperature).
Water when ground shows signs of drying; fertilize young trees with
nitrogen if growth is slow, leaf size relatively small, and leaf color
pale. Protect the exposed trunk from sunburn with white latex paint or
commercial tree wrap.
Aphids can be troublesome; they produce honeydew that drips–one
reason many gardeners avoid planting hazelnuts near patios. Wash aphids
away with a strong spray of water (perhaps mixed with mild dishwashing
soap). The filbertworm often ruins nuts by tunneling through
them–spray sevin in early and late July, and harvest and dry nuts
promptly. Pistachio: from the Middle East to the Central Valley,
Looking quite unlike its relative, California’s familiar
Chinese pistache, the nut-bearing pistachio (Pistacia vera) is a
smaller, somewhat less ornamental deciduous tree with slightly larger,
dark green leaves. Within about 10 years, it grows 25 feet high and as
wide. The picture at bottom right shows its rose-colored husks; ivory
nuts are inside.
Pistachios grow where summers are long, hot, and dry, and where
winters are moderately cold: to induce dormancy necessary for good nut
production, trees need at least 1,000 hours between 32[deg.] and
45[deg.]. A dormant pistachio easily survives 15[deg.], but late frosts
in spring–as well as strong winds and wet weather–can injure blossoms
and interfere with pollination.
You’ll need a male tree–‘Peters’–to pollinate at
the most 12 nut-bearing female tree–‘Kerman’–before flowers
can set fruit. If space is limited, graft a male branch onto a female
Plant pistachios in spring after frost danger passes. They begin
bearing after three or four years; a mature tree produces 40 to 50
pounds of nuts a year. Harvest begins when hulls loosen, mid-September
to mid-October. (Growers shake trees so nuts fall onto a catching frame
or canvas sheet.) Remove hulls, then dry in the sun or air until crisp
to the bite. Refrigerated nuts keep several years.
Prune young pistachios when dormant to develop four or five main
branches, the first ones 3 to 4 feet from the ground. Once a basic
structure is established, prune only to remove interfering or broken
Water frequently during nut development–June through
August–stopping in mid- to late August to promote ripening. Resume
regular watering after harvest. Fertilize in spring, using
approximately 2 pounds of 10-percent nitrogen fertilizer per tree.
Pistachios tolerate alkaline and saline soil, as long as it is well
drained. Trees are susceptible to verticillium wilt, a soilborne
disease favored by hot, dry soils; it’s most prevalent where cotton
has grown. Try to get trees on P. integerrima rootstock–the most
resistant. Macadamia: coastal Southern California, Hawaii
Native to eastern Australia, this 20- to 30-foot evergreen tree is
handsome enough to be planted as an ornamental, regardless of any crop
it might bear. Glossy, leathery leaves make a dense canopy; white to
red flowers appear late winter to early spring. By fall, clusters of
hard-shelled nuts hang like oversize grapes.
Rough-shell macadamia (M. tetraphylla and hybrids) thrives in
California but not in Hawaii. Nut husks are rough, leaves are spined
(new leaves are usually tinged red ro pink), and flowers are light green
or cream to brown. Nuts ripen October to January. ‘Cate’ is
the best known.
Smooth-shell macadamia (M. integrifolia) is grown in Hawaii, rarely
in California. Nut husks and leaves are smooth, and flowers are white.
Most nuts ripen July to November in Hawaii, November to March in
California. Many varieties are grown in Hawaii; some California growers
are experimenting with ‘James’, ‘Keaau’,
‘Pahala’, and ‘Smooth Queen’. The hybrid
‘Beaumont’ combines characteristics of both types; it is the
most productive macadamia for home gardens. Flowers are pink to red and
very fragrant; leaves are just slightly toothed. It’s fastgrowing
and more wind-resistant than the others.
Deep, fertile, well-drained soils are best, although trees tolerate
heavy clay and slow drainage better than avocado trees, which grow in
the same climatic conditions. (Macadamia is virtually immune to avocado
root rot, making it an excellent replacement tree where avocados
succumbed to that disease.)
Established macadamias tolerate some drought but perform best with
consistent watering. For best growth, fertilize regularly but always
lightly (some growers favor fish emulsion). Insect pests are rarely a
problem. Prune young trees to shape; encourage a strong central leader
with 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 10
years, 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 are
usually open at harvest time; if not, remove they dry. The nut inside
is hard to crack, even with a hammer. Special macadamia nutcrackers are
available from Gold Crown Macadamia Assoc., Box 235, Fallbrook, Calif.
In a dry, shady location, air-dry hulled nuts on hardware-cloth
trays for two to three weeks, then dry further in circulating warm air,
as in a food dehydrator.