Growing Dates:
Phoenix dactylifera
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Botanical Overview
Phoenix dactylifera, the true date palm, is a member of the palm family (Arecaceae). It is one of 13 palms in its Phoenix genus, all of which are called feather palms because of the shape of their fronds. This is the only date palm grown for its edible fruit, and it has hundreds of cultivated varieties throughout the world. The number of cultivars is uncertain because many cultivars have different names in different countries and even in different provinces and towns.
Description
Form:
Palm.
Lifespan:
While this palm may live and be productive for 150 years, its maximum productivity declines
after 35 years. Some commercial operations cut down the palm at 40-50 years of age, when it
is about 50-65' (15-20m) high.
Leaf retention:
Evergreen.
Growth rate:
Slow. Medjool palms are the fastest growing cultivar at 12-18" (30-46cm) per year.
Mature Size:
100-120' (30-37m) high.
Flowers:
Tiny, in large clusters, three sepals and three petals, male are white and female yellow-green.
Male and female flowers grow on different plants. Both clustered inflorescences are covered
with a hard, fibrous sheath (the spathe) which cracks when pollination is to begin. Female
palms are naturally pollinated by wind, and one male palm may be grown for 40-50 females.
Hand pollination is performed in commercial production and produces significantly higher
yields.
However, if fruit thinning is not done after hand pollination, the palm will switch to alternate
bearing, heavy one year, light the next.
Bloom:
Usually mid to late winter.
Self-fruitful:
This palm can produce fruit without pollination, but unpollinated dates will have no sugar
and are tasteless and inedible.
Years before fruiting:
3-8, depending on cultivar. They are in full production after 15-20 years.
Fruit:
Fleshy, with a thin skin and a single seed. Each palm produces 5-10 bunches, with each bunch
capable of having more than 1000 dates. Dates have four stages of ripening: immature green
(kimri), mature full-colored but astringent (khalal), soft with full size and weight (rutab),
and finally, hard, much more dry, and less astringent (tamar). Natural fruit drop may occur
twice, at about 25-35 days and 100 days after female spathe cracking.
Months for fruit to ripen:
8-10 months. Taking climate, cultivation, and age into consideration, a Deglet Noor can
produce 200-300 pounds (91-136 kg) of fruit per year while a Medjool can produce 150-225
pounds (68-102 kg).
Storage after harvest:
Up to one year after fully ripened when humidity is under 20% and the fruit are properly
packaged. Some dates in each bunch do not ripen past the third stage and must be picked
and exposed to heat, but not sun, to finish ripening.
Leaves:
Green to blue-green fronds, up to 15' (4.5m) long, 2' (0.6m) wide, slightly curved, having
a v-shaped central stalk with long, narrow, folded leaflets growing along both edges.
The life expectancy of a frond is 3-7 years, although some may survive longer.
Stems:
The trunk has a diamond pattern from cut fronds, can be up to 2' (0.6m) in diameter, and
may be wider at the bottom.
Each frond stalk has 4-6" (10-15cm) long sharp spines along both edges.
Commercial growers remove the spines.
Roots:
Finely branching, with no tap root. The roots are normally encouraged to grow out 15' (4.5m)
from the trunk in commercial production.
Cultivars of Note:
'Deglet Noor' long, thin, somewhat chewy,
moderately sweet. Originated in Algeria. Widely grown in California, grown in Nevada,
unsuccessful in Arizona.
'Medjool' large, soft, very sweet. A high quality
date that originated in Morocco. Grown in Arizona and California.
'Black Sphinx' smaller, sweeter, thinner skin than
Medjool. Low crop yield. Ripens during late summer rains which cause mold and rotting.
Originated in Phoenix, Arizona as a mutation of 'Hamlin'.
'Barhee' / 'Honey Date' smaller, very sweet
honey-caramel flavor with low astringency, usually eaten in the third stage of ripening
before becoming dry and wrinkled. Freezing and thawing are suggested to soften the date.
This rare palm is said to grow 16-32' (5-10m) high.
Wildlife:
This plant does not attract pollinating insects or birds.
Toxic / Danger:
Sharp spines at the base of each frond may cause severe injury unless removed.
Origin:
North Africa or the Middle east. The date palm has been domesticated for at least 8000 years,
obscuring its origins.
Cultivation and Uses
USDA hardiness zones:
8b-11.
Chill hours:
None.
Heat tolerant:
Over 120°F (50°C). Heat is needed for pollination and to ripen the fruit.
Drought and rain tolerance:
This palm is drought tolerant, but it needs abundant irrigation to produce a quality fruit
crop. Summer rain and humidity can harm ripening fruit.
Medjool is acceptably tolerant of summer rain and humidity, Deglet Noor is not.
Sun:
Full sun.
Planting:
Palm offsets should be planted in full sun, 20-40' (6-12m) apart, between late spring and
early summer. Date palms do poorly in containers.
Soil:
Well draining, sandy, 3-5' (1-1.5m) deep, pH 6.6-7.5 (neutral). Date palms are moderately salt
tolerant. The location must not be subject to standing water. Medjool is more tolerant
of clay soils than Deglet Noor.
Fertilize:
Apply a palm fertilizer in late winter. Recommended palm fertilizers are slow release
and have a 3-1-3 NPK ratio plus magnesium and manganese micronutrients. The most common
palm nutrient deficiencies are a lack of potassium, magnesium, or manganese.
Water after becoming established:
Basin irrigate once a week during fruiting to once
a month. Commercial growers irrigate an area 15' (4.5m) in radius around the trunk, often
using low overhead sprinklers to better control water distribution.
Bubbler irrigation is another alternative.
Mulch:
Do not mulch.
First Year Care:
The roots on offsets must not be allowed to dry out; offsets should be planted in
the field immediately with their fronds tied up for the first year. New offsets need
continually moist, well-draining soil. Protect them from wind and cold and provide all day
part shade. After planting, palm offsets establish very slowly.
Pollination:
Once the hard, fibrous sheath (spathe) has cracked on the male plant, it is tied with
a string to hold it together and removed. The spathe is then hung upside down to dry.
When dried, the fine pollen powder is sifted into storage jars. The pollen of any Phoenix
species, such as that of the Canary Islands palm, can be used to pollinate the true date
palm.
When the female spathe begins to crack and open, it is removed to expose the flower strands. Some center strands are discarded to thin the fruit crop and make pollination easier. Pollen-infused cotton balls are inserted at the top center of the flower strands and the strands tied together just below that point. Wind dispenses the pollen to the flowers.
When the female spathe begins to crack and open, it is removed to expose the flower strands. Some center strands are discarded to thin the fruit crop and make pollination easier. Pollen-infused cotton balls are inserted at the top center of the flower strands and the strands tied together just below that point. Wind dispenses the pollen to the flowers.
Pruning and fruit management:
Two-thirds to three-fourths of the small green dates must be removed. In Medjool date
cultivation, green dates are thinned along the strand so that those remaining have more
space around them to grow larger and get better air flow. In Deglet Noor cultivation,
the bottom two-thirds to three-fourths of all fruiting strands, or some entire strands,
are cut off.
These techniques do not reduce the total weight of the fruit crop. Thinning is necessary
to prevent the palm from going into alternate bearing mode, where it has a heavy crop
one year and a very light crop the next. Fruit bunches are bagged after thinning to
protect them from humidity, rain, sunburn and bird predation.
Cut flower clusters off as soon as they are fully open if fruit is not wanted, but be careful not to cut green fronds. Removing flower clusters provides the palm with more energy to grow additional fronds.
Cut off brown and yellow fronds, leaving green fronds to supply energy to the roots.
Keep grass and other vegetation at least 6' (1.8m) from the trunk.
Remove offsets at the base of the trunk unless you want them for growing additional palms, then keep only a few.
Cut flower clusters off as soon as they are fully open if fruit is not wanted, but be careful not to cut green fronds. Removing flower clusters provides the palm with more energy to grow additional fronds.
Cut off brown and yellow fronds, leaving green fronds to supply energy to the roots.
Keep grass and other vegetation at least 6' (1.8m) from the trunk.
Remove offsets at the base of the trunk unless you want them for growing additional palms, then keep only a few.
Litter:
Moderate: flowers, dates, dead fronds.
Propagation:
Offsets, growing from the base of the trunk, are removed when they develop their own
roots and possibly flowers, after 3-5 years. Offsets are clones and true to the parent.
Seed does not breed true, partly because of genetic variability and partly because palms hybridize easily with other palms. There is no way to tell a male plant from a female until the plant has grown for several years and begins to flower. Seedling-derived palms are generally inferior to offsets in the quantity and quality of their fruit production.
Seed does not breed true, partly because of genetic variability and partly because palms hybridize easily with other palms. There is no way to tell a male plant from a female until the plant has grown for several years and begins to flower. Seedling-derived palms are generally inferior to offsets in the quantity and quality of their fruit production.
Uses:
Fruit, ornamental.
Comments
Pollinated fruit in the second to fourth stage of ripeness can be ruined by
rain and high humidity. Enclosing the fruit bunch with a small-hole-perforated bag after
thinning may protect it. If rain occurs and the bunch is not bagged, consider harvesting
the fruit and exposing it to heat, not sun, possibly in a hot, dark, ventilated shed, to
finish ripening over many weeks.
A young palm should not be purchased from a nursery until it is old enough so
that the nursery can tell the difference between male and female palms.
Do you have additional information or a different experience for these plants that you would like to share? Email info@GardenOracle.com. All contributions are welcome and appreciated.
Do you have additional information or a different experience for these plants that you would like to share? Email info@GardenOracle.com. All contributions are welcome and appreciated.
Latest update: August, 2024
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