Gardening with Wilson

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.

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.

The first instalment of the Root Awakening column for 2010 was published today.

The first question dealt with white insects on kangkong plants and this could be an infestation of white flies. To eradicate these pests, spray plants using white summer oil or neem oil. Make sure you cover every part of the plant thoroughly, including the leaf undersides as well as any spaces between leaves. There is also a need to repeat application of the pesticide several times to ensure all progeny that hatch from eggs laid earlier are also eradicated. Check surrounding plants for any signs of infestations as well. Pests from these plants can migrate over at times. They should be sprayed as well if there is any signs of infestation. Alternatively, this could be a fungal disease called white spot that commonly occur in kangkong plant. Note that the spots are not mobile and cause the upperside of leaves to have yellow spots.

The second question was about the growing of the rangoon creeper in a container. Note that the Rangoon creeper is a big vine and it may not be a good idea to constrain it in a pot as it will be likely to suffer from water stress. A plant that has grown larger with a dense crown of foliage tend to have a higher demand for water as it transpires more. The amount of water that can be retained by the soil in a pot may not be sufficient for the plant’s needs. A plant that has been allowed to dry out may show yellowing leaves or shed its lower leaves. It is hence necessary to transplant your vine into a larger pot. One may want to transplant your plant into ground if it has grown too big. For plants grown inside a small pot, do increase the frequency of watering and apply a layer of compost on top of the soil surface to act as a mulch, which can help to retain water and reduce rate of evaporation.

The last question was about the growing of orchids. It is definitely not true that orchids do not require fertiliser. In fact, many species and hybrids need to be feed to grow healthily and produce flowers. Some fertilisers that are good for orchids include Gaviota (available from Far East Flora).

This orchid is an epiphyte and it is likely to be grown in a porous mixture such as  charcoal chips and this dries out quite quickly. Depending on the growing conditions, it may be necessary to water it at least twice daily, especially it is grown under direct sunshine. The problem described by the reader seemed to suggest that his/her orchid plant may be suffering from heat and moisture stress. One can consider adding a little sphagnum moss around the root zone to help retain some moisture. It may be necessary to increase the frequency of watering too. Do also try to relocate the plant to a less windy area or provide some protection by putting up a barrier to wind by growing them amongst some plants.

Do check out the book published by the Orchid Society of South East Asia entitled ‘Orchid Growing in the Tropics’ for more information on how to grow various orchids in Singapore.