Gardening with Wilson

Fans of Thai green curry (like myself) would be familiar with firm, pea-like fruits that are one of the ingredients of the savoury dish. Those fruits are produced by a plant that is botanically known as Solanum torvum, which is a relative of the common tomato and eggplant where all belong to the Solanaceae family. The plant is known via a range of common names which include devil’s fig, prickly nightshade, wild eggplant, turkey berry and pea eggplant.

Native to the Antilles, Solanum torvum is a slightly hairy but spiny, perennial plant, which adopts a shrubby growth habit. The plant can grow up to 3 m tall and features leaves that resemble those found on the eggplant (S. melongena). Flowers are produced in clusters and each blossom is white, in contrast those which are yellow produced by the tomato or violet by the eggplant. Fruits are small round berries which harvested for food in the immature stage when they are firm and green. Besides Thai cuisine, they are also used in Lao and Indian cuisines. When ripe, the fruits turn yellow.

It is also grown as a medicinal plant where the roots are traditionally used for poulticing cracks in the feet and seeds for the treatment of toothache in Malaysia. In Vietnam, the leaves are used to treat insomia and menstrual disorders. Extracts of the plant are used in India as an antidote for snakebite and insect stings and fruits are eaten to relieve stomachache. The fruits and leaves of this plant yield a steriodal alkaloid, solasodine, which is a precursor used for the manufacture of oral contraceptives.

Solanum torvum is a weed in tropical areas where it is common to find it in disturbed areas such as wastelands and construction sites. Birds which consume the fruits help to spread the seeds. It can also be introduced to new areas via equipment or transfer of contaminated soil. This plant is not usually available for sale in local nurseries and packeted seeds are also hard to come by (I have only come across a nursery selling  its seeds in packets imported from Thailand). Since it is a food plant, I have been wanting to introduce this plant to the Fruit and Vegetable Garden in HortPark but before I got to do so, two individuals appeared miraculously between the fruit trees in theme garden!

Besides useful being a source of food and medicine, this plant is valuable as a rootstock source to confer resistance towards bacterial and verticillium wilts in economic solanaceous crops such as tomato, eggplant and naranjilla. Grafted plants are said to be more vigorous and able to tolerate diseases affecting the root system.

As mentioned before, Solanum torvum can be grown from seeds but new plants can also be raised from stem-cuttings. If more than one plant are grown, they should be spaced about 2 m apart. They thrive in a sunny spot that is well-drained and fertile. It is rather drought-tolerant and relatively free from pests and diseases but may succumb to attack by soil nematodes.  Note that heavy rainfall will affect fruit set adversely.

Gynura procumbens is a common medicinal herb that can be seen being grown by home-owners, either in pots by high-rise apartment gardeners or in planter beds by more fortunate gardeners with an outdoor private garden or community garden.

I have only seen in one occasion where there is an English name for this herb, that is, the scrambling gynura, otherwise, it is better known via its Chinese name called ‘jian feng wei’ (尖凤尾, which translates into ‘pointed phoenix tail’) and Indonesian name, daun sambung mjawa. It should not be confused with daun dewa which is another related Gynura species.

In Singapore, Gynura procumbens is believed by the Chinese here to be one that possess the ability to lower blood pressure and sugar levels. Locals here will recommend you to eat 3 – 7 leaves daily in the raw form. I have tasted the leaves before and they have a mild raw taste which makes them quite easy to consume.

To date, there had been a limited number of scientific studies done on on this herb. A Singapore study that used diabetic rat models showed that an alcoholic extract of Gynura procumbens was able to reduce elevated blood cholesterol and triglyceride levels while another by a Korean group of researchers reported that this herb possessed anti-hypertensive properties in a rat model.

Besides the above medicinal properties, according to the Plant Resources of South East Asia (PROSEA), this plant is also used in Africa, where the boiled leaves are applied externally to relieve general body pains and raw leaves for rheumatic pains. Dried and pounded leaves are mixed with oil and applied as a poultice to treat skin compliants. It also used for the treatment of kidney problems and dysentery.

Gynura procumbens is generally regarded to be a relatively harmless herb to consume. In fact, in Java, the young shoots of this plant are eaten raw as a vegetable. Singaporeans may find it more palatable if the leaves have been blanched in hot water before consumption.

This plant grows easily from stem-cuttings. Seeds are not available. It is best grown in well-draining, fertile soil that is kept moist at all times. Semi-shade is preferred by this plant although it can be slowly adapted to grow in full sun, provided the plant does not dry out at the roots. Initial planting under direct sunshine will result in burnt leaves and stunting in growth. Growth should resume once the plant has acclimatised to its new growing conditions.

Gynura procumbens grows as a scrambling perennial plant with stems that can extend to 6 m long if left to grow. The fleshy leaves are bright green that are rather smooth to touch. The shape of leaves can vary depending on the growing conditions and they can range from roundish to ovate in shape but are all shallowly toothed at the margins.

In shade, they are darker green and appear rather flat but under direct sun, the two sides of each leaf may develop a slight V shape along the mid-rib and take on a lighter green colour. The plants I have seen so far have green leaf undersides although I read before that there are plants with purple undersides.

The stems can be totally purple or have patches/specks of purple. From the above description, one can observe that Gynura procumbens can be highly variable. To date, I have not seen flowering specimens before in Singapore.

The water hyacinth is perhaps the first floating water plant we learnt about in school and we were also told that they are fast-growing and troublesome weeds in waterways because of their rapid growth and ability to form dense, impenetrable mats of vegetation which hinder navigation and fishing, obstruct irrigation and drainage of farm land and crowd out other plants. As a result of this, this water plant has earned itself a bad name.

But do you know that the water hyacinth is one beautiful water plant? For those of us who have seen it bloom, you will know what I mean. Water hyacinths are members of the Pontederiaceae family which produce spikes of pretty lavender flowers (like the bulbous hyacinths) on top of lush, shiny leaves. There are two species of water hyacinths that one can can choose from.

The first and most common species is Eichhornia crassipes. The leaves of this plant grow from a rosette and the rounded base of each leaf is inflated and spongy which helps to keep the plant afloat on the water surface. For those of us who have picked up one plant a pond, one will observe that the water hyacinth has feathery, freely hanging roots are almost black in colour. These roots do not anchor the plant to any base and hence a water hyacinth is free to float around. Under optimal growing conditions, water hyacinths are prolific bloomers but each flower is rather short-lived, lasting for at most a day or two.

Plants also propagate rather freely by sending out new plants via stolons like a strawberry plant. Although its growth rate can be a nightmare, people have put the water hyacinth to good use after finding out it has phytoremediation properties as it can soak up soluble heavy metal ions and cyanide in polluted waters. The water hyacinth plant also has abundant nitrogen content and it has been harvested and used a substrate for biogas production.

People have also harvested water hyacinths from overgrown colonies for making green manure, compost and mulch for soil improvement. It is sometimes used as a fodder for animals for buffalos and pigs (this is why in Singapore, the older generation calls this plant as the ‘pig plant’ (猪草)). The water hyacinth is also eaten has a leafy vegetable in Taiwan and Java but do exercise caution before consumption as this plant can be contaminated with toxins if it is harvested from polluted waters.

There is another species of water hyacinth known as Eichhornia azurea and its common name include the creeping water hyacinth, peacock water hyacinth. It is less common in Singapore and its flowers are more lavender in colour and smaller compared to Eichhornia crassipes. One will also notice that the yellow spot in the dorsal petal of this species to be more prominent which is not surrounded by a darker patch of purple seen in Eichhornia crassipes. The plant also adopts a slight different growth habit as it grows along a long stem unlike Eichhornia crassipes which adopts a rosette growth habit. Its roots are also less feathered. Eichhornia azurea is propagated via stem-cuttings instead of separation of its stolons (for Eichhornia crassipes). The stems of this species are used to make furniture and baskets.

Both water hyacinth species are sun-lovers and demand a location with more than 6 hours of direct sunshine to grow well. If they are grown in a shady area, one will notice they will simply disintegrate in a matter of a few days.

Water hyacinths are good for ponds which suffer frequently from algae blooms as they help to soak up excess nutrients! Always keep a look out for the growth of your water hyacinth plants in such a situation – promptly remove excess plants before they invade your pond.

If you are afraid they will take over your pond, grow them in a container of water that has some fertiliser added to it. Note the type of fertiliser added as some are harmful to fish if you intend to have fish in the containerised water garden. Fish is recommended as they help to eat up mosquito larvae.

Interestingly, water hyacinths can also be grown in soil. They do well in soggy soils as long as there is water over their crowns!

A maximum of 30 participants attended the recent gardening workshop entitled ‘Success with Western Cooking Herbs’ that was conducted at HortPark on 23 Jan 2010. It was the first gardening workshop in a series that was crafted to enhance horticulture excellence among Singapore gardeners. Topics covered will be those that will be more relevant to local gardeners. For this workshop, I was surprised by the great turnout and hope that the workshop had been an enjoyable and fruitful experience for all.

I was the instructor of this first workshop and shared with my participants some tricks that will enable them to successfully grow popular Mediterranean culinary herbs in tropical Singapore. With the lack of a local supply of potted culinary herb plants, participants got to learn how they can start their first herb plants from materials bought from the local grocer. Each participant got to bring home a pot of culinary (not commonly available in local nurseries), some pre-mixed soil, herb seeds, rooting powder and a CD containing the workshop presentation slides. Even though 3h was a little long, there is still insufficient to cover such a broad topic. I will work into future workshops more hands-on session.

For those of you who missed this first workshop, do look forward to a second run that is planned to take place in the second half of this year. Gardening enthusiasts can look forward to attend other basic gardening workshops in the series which include basic plant propagation techniques, pest and disease identification and management, high-rise gardening and starting your first outdoor garden.

The third and last instalment of the Root Awakening column for Jan 2010 was published today.

The first question was about the growing of hibiscus plants from stem-cuttings.  Hibiscus can be propagated via both softwood and semi-hardwood stem-cuttings. Softwood cuttings are taken from soft, succulent, new growth. Shoots are suitable for making softwood cuttings when they can be snapped easily when bent and when they still have a gradation of leaf size (oldest leaves are mature while newest leaves are still small). They usually root faster than semi-hardwood cuttings.

Semi-hardwood cuttings refer to stems taken from partially mature wood. Such stems are reasonably firm, the leaves of mature size and may have some bark on them. Avoid material with flower buds if possible and remove any flowers and flower buds when preparing cuttings so the cutting’s energy can be used in producing new roots. Take cuttings from healthy and disease-free plants. Take stem-cuttings from plants that have been well-watered and do so in early morning when it is cooler.

Cuttings are best around 4 to 6 inches long by using a pair of sterilized sharp pruning shears. Remove the leaves from the lower one-third to one-half of the cutting. Cut large leaves in half to reduce water loss. Dip the cut end of a stem-cutting with some rooting hormone powder made into a slurry.

Stick stems into a new soil mixture that is sterile, low in fertility, and well-drained to provide sufficient aeration. Insert the cuttings one-third to one-half their length into the medium and maintain the vertical orientation of the stem. Cover the cuttings with a plastic bag and place in indirect light. Keep the medium moist until the cuttings have rooted. Rooting will be improved if the cuttings are misted on a regular basis.

Rooting time varies with the type of cutting, the species being rooted, and environmental conditions. Grow cuttings in a pot until they attain a larger size before transplanting to a permanent location.

The second question was about the shrivelling of leaves of a tree. It could be due to hot and dry weather. Under such weather conditions, it may be beneficial to ensure the plant is well-watered and roots are kept moist. Do also apply a layer of mulch around the root zone to ensure it stays moist and cool. If possible, provide some form of shade during this period. It could also be due to a bout of insect infestation and hence it would be necessary to check if there is any and ensure that all pest infestations have been cleared. Any remaining population can re-infest a plant if not properly eradicated. Several rounds of pesticide application may be necessary.

The last question was about the pruning of a money plant. A money plant will not die if its growing tip has been cut. The plant will respond by producing side shoots and this can take any time at least two weeks, depending on the growing conditions. Cutting back a money plant can be beneficial at times as it helps to keep a plant’s growth in check and can help to maintain or promote a bushier growth habit.

I contributed an article written on two small fruit trees that can be grown in containers in the January 2010 issue of the Serangoon newsletter. The two plants included the Surinam cherry (Eugenia uniflora) and Barbados cherry (Malpighia glabra). Both fruit trees produce fruit when they are quite young and can be grown in containers. They bear loads of attractive looking fruit which can cover the whole shrub/tree and between the two, I like the Surinam cherry more – which is obvious – as the fruits of the other are very sour!

Surinam cherry and Barbados cherry will do pretty well if grown under direct sunshine for 4 to 6 hours daily. One can grow them inside a container filled with fertile and well draining soil. They should be kept moist and not allowed to dry out completely or experience wet feet for prolonged periods. Fertilise them to promote growth and fruit production.

This article is a summarised version of two posts that I have put up on this blog. To know more, do refer to them via the links given below:

Barbados cherry

http://gardeningwithwilson.com/2009/07/13/the-pretty-barbados-cherry-tree/

Surinam cherry

http://gardeningwithwilson.com/2009/09/03/the-pumpkin-like-surinam-cherry/

Last Sunday, airplant growers gathered at HortPark’s multi-purpose hall to listen to the first gardening talk in 2010 entitled ‘Airplants – Plants For The Modern Gardener’. It is the first in a series that have been planned to take place in odd months of the calendar year that will not just be a talk but more of a gardening talk show that encompasses interviews and demonstrations involving hobbyists and landscape industry partners.

I decided to kick-start this special talk show series with airplants as they are small, relatively ‘clean’ and easy to grow by most gardeners who live in high-rise apartments. The ease of their cultivation makes them good for modern urbanites who are often too busy to find time to tend to a garden where space is also a constraint for many. Commonly called “airplants”, these plants are members of the genus Tillandsia, which are mainly epiphytes that literally live on air. They are relatives of the pineapple and hence make an equally auspicious symbol for the the Lunar New Year which will fall in mid-February this year.

The 2h session was not all talk or demonstration by myself. I have invited three fellow airplant enthusiasts from my Green Culture Singapore discussion, namely, Kevin Cheong (greenhorn), Benedict Tay (benetay) and Lynnette Terh (Velvetine) where they shared their varied airplant growing experiences which range from an outdoor community garden, high-rise apartment window/balcony to the rooftop garden. Near the end of the session, I also demonstrated to participants on how they can construct a unique 3D vertical garden using a range of epiphytic plants which included airplants, antplants, ferns, Dischidia and Hoya.

The second instalment of the Root Awakening column for Jan 2010 was published yesterday. As usual, answers to three gardening questions were provided.

The first question was about the growing of the flaming beauty (Carphalea kirondron), which is a sun-loving shrub that is also a heavy feeder. It prefers to be grown in consistently moist soil that is enriched with well-rotted compost. One has to watch out for small sucking insects such as aphids, mealy bugs and white flies that may feed on young, emerging shoots. Attacks by these pests can cause new growth to die back. Spray with neem oil or white summer oil to eradicate these pests.

The second question was about a reader’s proble in growing of a rose said to be from Kunming. Note that the rose plant needs to be protected from the tropical mid-day sun. Roses like to be grown in a sunny area with moist, well-draining, fertile soil that is supplemented with organic matter such as compost. One can fertilise plants with a suitable rose fertilizer or water-soluble ones like Gaviota and Phostrogen, made up according to the manufacturers’ instructions. Heat can be a serious problem with roses during the hot season where new shoots and buds can dry up as a result. Grow in pots so that it is easier to move plants to semi-shaded areas during that time.

Also, rose plants are commonly affected thrips or spider mites that commonly attack young growth and new flower buds of rose plants. To eradicate these pests, Condifor (active ingredient is imidacloprid), which is a systemic pesticide has been found to be particularly effective. Before spraying, it is best to prune away affected parts so as to reduce the population of pests.

The last question dealt with the lack of flowers of a yellow frangipani plant. Note that this plant is a sun-lover and one has to ensure his/her frangipani plant receives sufficient duration of direct sunshine. A recommended duration would be at least 6 hours daily. It would be beneficial to feed the plant with a fertiliser to promote flowering that is high in phosphorous content. Refrain from fertilizing your plant with only organic fertiliser which is usually rich in nitrogen that promotes growth of foliage. Make sure that the soil pH is right so that nutrients required for growth are not locked up or in excess which will affect the plant. The optimal pH range for frangipani is from 6.4 to 6.8.

Known via a range of common names which include devil bean, large yellow rattlebox and wedge-leaved crotalaria, Crotalaria retusa is a highly ornamental plant that you can grow in your garden. A member of the bean family (Fabaceae), it produces bright yellow flowers that are borne on an upright spike which is presented promindantly above a mass of jade green leaves. For ornamental purposes, this plant is best grown in mass in either a flowerbed or as a border plant.

Sometimes found growing as a weed in wastelands, Crotalaria retusa grows as an annual herbaceous shrub that can attain a height of about 1 m. This plant can only be from seeds and the process is an easy one but trying to get some seeds can prove to be difficult. It loves a sunny spot that is also well draining. Being a legume, Crotalaria retusa can fix its own nitrogen from the atmosphere and hence can be grown in nitrogen-poor soils.

Besides being useful as an ornamental plant, Crotalaria retusa has an interesting characteristic that will probably interest kids. The pod-like fruit this plant produces, when mature and dry, becomes a rattlebox that can be shaken and heard. The common name of this plant ‘rattlebox’ is derived from this interesting feature.  The genus name Crotalaria is derived from the Greek word, κροταλον, which refers to the musical percussion instrument castanet. If you are looking for a candidate to grow in your sensory garden, plant Crotalaria retusa in it to confer the sound/audible component.

Like other legumes, Crotalaria retusa can be grown as a green manure, where mature plants can be worked back into the soil to add nitrogen. It is also grown as a source of plant-derived fibre and dye.  Crotalaria retusa is also grown as a medicinal plant. According to Plant Resources of South East Asia (PROSEA), its roots are used against coughing up blood while its leaves are mixed with those of another relative, Crotalaria quinquefolia, and consumed or applied externally against fever, scabies, lung diseases and impetigo. Flowers and leaves are both edible as vegetables due to their low alkaloid content and are purportedly sweet. Seeds are roasted and eaten in Vietnam. Note that this plant is also nematode-resistant and studies have found dried plant parts can be worked into the soil as a soil amendments to deter and reduce root galling by the root-knot nematode, Meloidogyne incognita.

Lastly, note that Crotalaria retusa is a butterfly host plant. According to the Butterfly Circle website, Crotalaria retusa is the food plant for the pea blue butterfly (Lampides boeticus). Unlike other butterfly caterpillars that chew up leaves, the first two instars of the pea blue bore into flower buds of this plant and consume the flower parts contained within. The larger 3rd and final instar caterpillars will move on to eat the developing seeds within seed pods. For more information on the pea blue butterfly, please refer to the webpage below:

http://butterflycircle.blogspot.com/2009_09_12_archive.html

Do your part for the wildlife and environment around us, try to grow this plant without the use of pesticides. In rapidly urbanising Singapore, we are losing loads of our native species of flora and fauna without many of us knowing. Butterflies have an important role in our environment and one of the most obvious role they play is that of a pollinator where they help to transfer pollen that help plants to set seed and ensure the survival of subsequent generations.

The e-newsletter of the National Parks Board is now available online for all to read and can be accessed via the link given below:

http://www.nparks.gov.sg/cms/nparksenewsletter/issue4/

There are four feature articles to read from and the one featured on the main page is ‘Getting Festive with Fittonias’.  Lately, I am fascinated with some of the newer nerve plant (Fittonia species and cultivars) due to their unique foliage features. Some of them have very vivid red leaves that makes them so suitable for use in the upcoming Chinese New Year where red is an auspicious colour. What’s more these plants don’t die away like many other festive plants. They are quite easy to care for and make good Valentine’s Day gifts. Read on to find out more!

Getting Festive with Fittonias

http://www.nparks.gov.sg/cms/nparksenewsletter/issue4/gardening/gardening-festive.html

My colleagues from my Hort Outreach team contributed two other articles. One of them is by Jin Hong  and Pearl that was written on how you can grow your own pea sprouts, which is a leafy green that is so easy to grow from seeds bought from the supermarket. They make a healthy vegetable dish for the reunion dinner this coming Lunar New Year!

Pea Sprouts: Easy To Grow, And Tasty Too

http://www.nparks.gov.sg/cms/nparksenewsletter/issue4/gardening/gardening-pea-sprouts.html

The second article, written by Joyce and Pearl, was on the topic of pots, those that we use to grow our plants. In it, you get to read more about the differences between plastic and clay pots and containers that are termed as a ‘grow pot’ and a ‘cache pot’.

Pottering Around With Plant Pots

http://www.nparks.gov.sg/cms/nparksenewsletter/issue4/gardening/gardening-pottering.html

The last article was contributed by Maxel, from Community in Bloom and one can get to know more about community gardening in ST Kinetics.

Green Fingers At Work In ST Kinetics

http://www.nparks.gov.sg/cms/nparksenewsletter/issue4/gardening/gardening-greenfingers.html