Thursday, December 27, 2012

Carissa macrocarpa (natal plum)

Carissa macrocarpa (syn. C. grandiflora) is a very attractive shrub that bears edible fruits. It is sometimes called natal plum, but it is not a plum, belonging instead to the Apocynaceae family.
Very fragrant white blooms appear near the stem tips whenever the plant is in growth. The fragrance doesn't carry far, so it's best enjoyed up close. Individual flower are five-petaled and about 2 inches across. Pollinated flowers are followed by 1-3 inch long reddish fruits.
When the fruit turns dark red, starts to soften, and gives slightly under gentle pressure, it's time to pluck it off and pop it in your mouth. Even fully ripe fruits have a slightly milky sap, but it is undetectable when eaten whole.
Each fruit contains a few small brown seeds that are soft enough to chew or swallow. The chewed seeds do detract somewhat from the cranberry/raspberry/strawberry flavor, so I usually swallow them whole or spit them out.
The plant can be relatively slow growing, but eventually reaches 8 feet. Branching often takes on a layered look, and the stems have a cluster of sharp spines at each leaf node.
The 2-inch diameter rounded, leathery leaves are very dark green and have a glossy sheen.
The entire plant exudes a milky sap when injured. Some low-growing and thornless cultivars exist that are used commercially as groundcovers.
Carissa macrocarpa is native to South Africa and will grow in sun or shade. It is drought-tolerant and resistant to salt spray, making it popular on oceanfront properties. It is recommended for USDA Zones 9B-11.

Wednesday, November 28, 2012

Chayote (Sechium edule)

Chayote (Sechium edule) is a perennial squash that will produce well for several years. The vines grow rapidly and can extend more than 50 feet from the base of the plant. This requires a strong support. A sturdy fence or horizontal trellis is ideal, as it keeps the fruit within reach and easy to pick. Other alternatives would be to plant on a vertical trellis or small tree. The vine attaches itself and climbs by means of tendrils that curl around whatever support is available.
Chayote will grow across the ground like other squash, but they take up a tremendous amount of space in the garden and you'll have to pick through the vines to find the mature fruits. Leaves are similar to most other cucurbits and grow to about 8 inches in diameter.
Chayote are native to a wide swath of Central America and have been cultivated there since pre-Columbian times. A long growing season is required, as the formation of flower buds isn't initiated until the days shorten in fall. It takes about another month for the flowers to develop and open, then an additional month for the fruit to grow and mature. It is recommended for USDA Zone 8 or higher.
Flowers grow on a stalk emerging from the leaf axils. They produce a lot of nectar and chayote is said to be one of the best honey plants. Hummingbirds are also attracted to the blossoms.

Female flowers are at the base of the stalk, one per stalk. The male flowers open in sequence on the elongating stalk. In frost-free areas, crops may be harvested nearly continuously for about 6 months, and older plants may yield several hundred fruits per year. I've harvested as many as 45 squash in a single day from one plant.
Individual fruits typically reach about 6 inches in diameter, but they are usually harvested at a smaller size for commercial production. Multiple varieties exist, some with deeply furrowed or very spiny skin. The base of the fruit is distinctively grooved or puckered.

The chayote squash is prepared by peeling and then boiling, steaming or baking. It's also possible to cook it first and then remove the skin, as is done with most winter squash. It may also be eaten raw or used like cucumber in salads. The skin of fruits picked before they reach full size is tender and edible like that of summer squash. As the fruit ages the skin becomes more tough and fibrous. Young raw fruits have a slightly sweeter taste than older ones.

The sap from the raw cut fruit can cause skin irritation or numbness in some individuals. This may vary from plant to plant. I have experienced some temporary reduced sensitivity in my fingertips after peeling a large quantity of raw fruit, but I find it less bothersome than wearing gloves.

The squash remains firm after cooking and has a mild, slightly buttery flavor. There is a large single seed at the center of each fruit that has a delectable nutty taste. The raw seed tastes something like raw English peas.

The tendrils and young shoots are edible when steamed, and unlike many "edible" shoots or vines, these have a pleasant taste.

The large tuberous roots can also be dug up and eaten as a vegetable after cooking. The tuberous portion of the plant is known as ichintal. Older roots can supposedly weigh up to 20 pounds. It may be possible to dig up a root and carefully remove it without affecting the health of the plant, but I think it would be difficult. I dug around the base of a 2-year old plant and exposed the top of the storage root. The ichintal is the large, fat root growing straight down directly from the base of the plant and you can see the lateral roots spreading out to the side.
I think it would be very difficult to dig the ichintal without seriously damaging the plant, so I'm leaving it alone for now. If we get a hard freeze some year and the plant dies back, I'll try and dig the root then.

The rest of the root system spreads out over a 12-foot diameter area, so give it plenty of room and only plant shallow-rooted plants within the root zone. A full sun location is best for fruit production. In regions where the top inch or so of soil freezes in the winter, a thick mulch applied in fall will protect the crown of the plant until growth resumes in the spring.

Excess harvest can be stored by wrapping the squash in newspaper and keeping it in a cool location. It can also be frozen for use during the off-season. The squash is a very good source of dietary fiber, vitamin C, vitamin K, folate, zinc, copper and manganese, and it is also a good source of niacin, vitamin B6, pantothenic acid, magnesium and potassium. The green shoots are even more nutritious.

In some regions, the strong dried stems are woven into baskets and hats.

Chayote is propagated by planting the entire fruit, buried about halfway into the soil. New shoots and roots will quickly sprout from the base of the squash and start a new vine that will produce the following fall.

Monday, November 26, 2012

Luffa aegyptiaca

Luffa aegyptiaca is an annual climbing vine that produces a fibrous, sponge-like fruit commonly used in many bath and body products. These natural plant-fiber sponges are used in the bath or shower to gently exfoliate skin, in the kitchen to scrub pots, pans and non-stick cookware, or outdoors to wash cars, trucks and boats.

Luffa requires a long growing season. If planted early enough in the year, a few fruits will form in the spring that ripen by fall. During the long hot days of summer, pollination is inhibited, but resumes with the shorter days of autumn. If you have a 10-12 month growing season, you'll get a bumper crop of luffas at the end of the year.
The showy yellow male flowers open one at a time on an elongating upright stem.
 Female flowers are solitary with a pre-formed fruit. Individual blooms are about 3-4 inches in diameter.
Pollinated flowers result in a rapidly growing fruit that eventually reaches 15-18 inches in length. There are other cultivars of luffa; they may be longer and thin, short and thick, or with ridges on the skin. Young fruits that are up to 6 inches in length may be cooked and eaten as a vegetable. In China, the flowers, leaves, and young shoots are also eaten.
As older fruits reach maturity, the skin changes from dark green to yellow-green. Finally it turns brown and dry. At this point it's ready to harvest for the fibrous sponges. Harvest as soon as the skin turns brown. Clip the fruit off to avoid damaging the vine because more fruits are still forming. When the skin is dry and brittle, crack it open and peel off the outside.
Inside you'll find a beautiful luffa that may be any shade of brown to nearly white. Shake out the seeds and wash the fiber thoroughly to remove plant sap. Dry it in the sun and your luffa is ready to use. Leave it whole for use in the bath, or cut it into conveniently sized pieces for other uses.

Luffa aegyptiaca is native to tropical Africa and Asia. The vine grows more than 30 feet long, so give it plenty of vertical space. They'll quickly climb a trellis or fence and cover adjacent trees or shrubs. Grow in full sun for best flower and fruit production. Here's a photo of one of mine covering a sabal palm.

Sunday, November 25, 2012

Sunchoke (Helianthus tuberosus)

Helianthus tuberosus is a species of sunflower that produces edible tubers commonly referred to as sunchokes. The plants grow 6-10 feet tall, depending on variety, and are covered with bright yellow sunflower blooms all summer long. The flowers are about 3 inches in diameter and lightly fragrant. Each plant sends up multiple stems that generally remain unbranched until flowers start to form.
In the fall, as the days shorten and become cooler, the plants decline and turn brown. In short-season growing areas, frost may be the determining factor for the end of growth.

Once the plants are dry and brittle, it's time to dig the tubers. Most of the edible portions will be within 12-18 inches of the main stem and within 8 inches of the soil surface. I dig a circular perimeter around the plant and then work toward the center excavating the tubers. In sandy soils I do most of the digging with my hands. It's easier to find small tubers this way. In heavier soils a shovel or potato fork works well.

Watch my video on digging sunchokes here

It seems that sandy soil also produces knobbier tubers, while heavy soils produce smoother, more compact tubers. The photo above shows tubers dug from heavy, mucky soil, while the photo below shows the same variety grown in almost pure sand.
Here is a photo of some tubers grown in compost:
The harvest will consist of tubers ranging in size from tiny pips to pieces weighing a couple of ounces. The total yield per plant averages 2-4 pounds in typical garden conditions, although yields as high as 6-10 pounds have been reported for commercial plantings. Any pieces you miss while digging will remain dormant over the winter and then grow new plants as the soil warms in the spring.
A few named varieties exist that have been selected for skin color, yield, or tuber shape. Some have reddish skin and some have more torpedo-shaped tubers.

The harvested sunchokes should be stored in the refrigerator in a sealed container, where they'll keep for several weeks. If they become dehydrated they'll feel rubbery, but they'll firm up again when soaked in water.
After they are washed and lightly scrubbed, sunchoke tubers can be eaten either raw or cooked. The raw tubers have a sweet, crisp quality like jicama or water chestnuts, and are excellent alone or thinly sliced in salads. They can be added to stir-fries, soups and stews. They can also be cooked like potatoes.
Nutritionally, sunchokes are a very good source of iron, and a good source of thiamin, phosphorus and potassium. The carbohydrates in the tuber are stored as inulin, which breaks down into fructose rather than glucose during digestion. For diabetics, this makes it a good substitute for other starchy foods like potatoes.

Helianthus tuberosus is an annual, only living for one season, but the buried tubers that re-sprout in the spring give it a perennial growth habit. It is recommended for USDA Zones 3-9.

The species is native to the eastern half of North America, and many Native American tribes consumed the tubers which they called sun root. They are also known as topinambour. In some regions, the plants and tubers are mysteriously known by the misleading and nonsensical name of Jerusalem artichokes, even though there is absolutely no connection to either Jerusalem or artichokes!

Thursday, November 8, 2012

Odontonema strictum (Firespike)

Odontonema strictum is a great shrub for late summer through early winter blooms. The red tubular flowers attract hummingbirds and butterflies.
Also known as firespike or cardinal's guard, this plant grows 3-5 feet tall in full sun to half shade. Blooms appear in clusters at the tips of the stems and the inflorescence continues to elongate throughout the flowering period.
Often, the flower spike will take on a crested form as the season progresses.
Firespike is classified as an herbaceous perennial, since it doesn't form woody stems. The broad green leaves are about 6 inches long, and deer are known to feed on the lush foliage.
Odontonema strictum is native to Central America and is recommended for USDA Zones 8-11. Frost will damage the foliage, but the plants quickly re-sprout from remaining green stems, or from the crown of the plant at soil level.
Plants are very drought-tolerant once established, but thrive in evenly moist soils.
O. strictum is considered to be synonymous with O. cuspidatum.

Related reading: Odontonema callistachyum

Thursday, October 25, 2012

Carica papaya

Carica papaya is a fast growing tropical herb that produces delicious fruit. Many different strains exist, producing fruit sizes ranging from 1 to 20 pounds. The flesh color also varies from plant to plant and may be yellow, orange or reddish.

Papaya grows rapidly. Under ideal conditions flowers and fruit will be produced the first year from seed, often starting when the plant is only 4-5 feet tall. It takes 3-4 months from flower to mature fruit.

When the skin is mostly yellow it's time to pick the fruit, cut it open, and enjoy! Even the black seeds are edible and have a peppery taste similar to nasturtium.

Mature green fruits may be cooked as a vegetable. A young plant will produce 2-3 ripe fruits per week. Older, branched plants will produce many more.
Leaves are palmate and deeply lobed, often growing more than 2 feet across. In the East Indies, young leaves are cooked and eaten like spinach. Crushed leaves wrapped around a tough cut of meat before cooking will help tenderize it. The milky latex exuded by immature fruits is also collected and used in commercial meat tenderizers.
Old plants form thick trunks that support a branching canopy of foliage. Branching is often stimulated by some injury to the growing tip, such as a light freeze. This 10-year old papaya has a trunk circumference of 4.5 feet at the base.

Carica papaya has a complex sexual morphology. Plants may be male, female or hermaphrodites. All flowers are very fragrant.
female flower
male flower

Papaya is believed to have originated in Central America, but is now cultivated in tropical regions around the world. They are recommended for USDA Zones 10-11, but due to their rapid maturity, can be successfully grown in Zone 9 as well. I have had several plants live more than a decade in my Zone 9B garden. Most references indicate that productivity rapidly declines with age, but I find older, branched specimens produce far more fruit than young, single-trunk plants.

Thursday, October 11, 2012

Podranea ricasoliana

Podranea ricasoliana is a vigorous vining plant that blooms throughout the warm months of the year, when the plant is actively growing. The pink flowers appear in clusters on the ends of new growth. Each flower is about 2 inches across and lightly fragrant. Unfortunately the fragrance doesn't travel, so you'll have to stick your nose right into the bloom to catch the scent. There are about 18-20 flowers per cluster, opening several at a time.
Although this is a vining plant, the stems do not twine, grasp, or root onto their supports. Instead, the long flexible stems head skyward and simply lean or lay across supporting objects, which are often adjacent trees or shrubs. It quickly and easily climbs to 30 feet or more. When stems reach the top of a tree they arch over, and either flower or head back to the ground and form another plant.
If no vertical objects are nearby to climb, the stems run across the soil surface until they find a place to climb. Wherever stems contact the soil, they'll send out roots and start a new plant so it's imperative to keep horizontal shoots clipped off. Old plants develop a woody trunk that is deeply furrowed with a corky texture.
Leaves are dark green, pinnate, opposite on the stem, and 6-8 inches in length.
It's unclear where Podranea originated, but it is common in tropical and subtropical regions around the world. The plant will grow in nearly any location, surviving heat, drought, and several degrees of frost. Flowering is best in full sun. It is recommended for USDA Zones 9-11, but may survive as a perennial in slightly colder locations.
Common names include pink trumpet vine and Port St. Johns creeper.

Tuesday, September 18, 2012

Doritis pulcherrima

One of the most reliable orchids for late summer and fall blooms is Doritis pulcherrima. Even the smallest plants rarely fail to send up a spike each year.
This genus is closely related to Phalaenopsis and much hybridization between the two has been done over the years. The Doritis genes bring smaller plant size and a more erect flower spike to their progeny.
The natural species usually only has a leaf spread of 4-6 inches and several plants can grow comfortably together in a 4-inch pot.
They multiply by clumping so it's typical to see plants grouped together in a single pot. When they fill the pot it's time to divide them, giving each one its own space. I like to divide in the spring, giving the young plants all summer to get established and ready for the annual bloom.
Individual flowers are about 3/4 inch across, with petals strongly recurved back toward the stem. The blooms open a few at a time, progressing up the spike, which continues to elongate as new buds are produced. The flowering period easily lasts for 2-3 months, with the spikes often reaching 3 feet in height. In high light the spikes are mostly vertical, but in shade they tend to bend toward the light.
Doritis pulcherrima is a fairly cold-tolerant species and survives brief temperatures in the upper 20°F range if situated under dense trees or shrubs during cold snaps. It also tolerates higher light and drier conditions than its Phalaenopsis relatives.

Friday, September 14, 2012

Turnera ulmifolia

Turnera ulmifolia (TERN-er-uh  ul-miff-FOLE-lee-uh) is an ever-blooming shrub that thrives in subtropical gardens. The bright yellow flowers each last only a day, but new flowers are continuously produced. The plant grows about 3 feet tall in a single season and requires very little care. It is drought-tolerant and thrives in nearly all soil types. The dark green leaves are usually about 2-4 inches in length and the flowers are about 2 inches in diameter.

Turnera ulmifolia is sometimes called yellow alder, but it is not an alder so that is a poor choice for a common name. There's really no reason to call it anything other than Turnera. It is native to the Caribbean and is recommended for USDA Zones 9-11. A hard freeze may knock it back to ground level, but it will quickly recover when the weather warms. In colder locations it can be grown as an annual. The plant reseeds itself easily and you're likely to find seedlings coming up all around the garden. The seedlings are easily identified by the distinctive leaf, so they can be pulled, transplanted, or allowed to remain where they sprout, depending on your preference.
Although you may find seedlings coming up in random locations, they generally aren't prolific enough to become weedy. The flowers attract butterflies, especially Gulf Fritillaries and Sulphurs.

Thursday, August 9, 2012

Cuban Oregano (Plectranthus amboinicus)

Plectranthus amboinicus is a tender perennial herb with many common names including Cuban oregano, Spanish thyme, oregano brujo, broadleaf thyme and big thyme.
The leaves are chopped and used with stuffing, salads and meats. It can also be used as a substitute for oregano or sage. If you've picked a few leaves for use in the kitchen and didn't use them all, do not refrigerate what's left. This is a tropical herb and refrigerator temperatures quickly cause brown deteriorating spots. Excess leaves store very well in a sealed plastic baggie or container at room temperature for up to two weeks.
The leaves are large, fleshy and covered with fine hairs.
In full sun the leaves are generally 3-4 inches in diameter, but with a little shade they can easily reach 6" or more in length. Long stems tend to flop over, so keep the plant compact by frequent harvest of the growing tips for use in the kitchen.

This plant is recommended for USDA Zones 9B-11. In areas that experience frost, Cuban oregano is best grown as an annual during the warm months. In frost-free areas the plant is perennial, developing a woody stem at the base and growing about 2 feet in height.
Older plants are not as vigorous, so I like to plant fresh starts each spring that quickly become large specimens. Cuban oregano thrives in sun or part shade. There is also a variegated form that is slower-growing.