Hoya Macgillivrayi is an indigenous climber originally from Australia. It was named in honor of Dr. William David Kerr Macgillivray, a famous ornithologist and naturalist.
He collected the type of specimen in north Queensland, Australia, at the end of the 19th century.
It is one of the rarest species of Hoya, and the IUCN (International Union for Conservation of Nature) included the plant in the so-called red list of rare or affected plants in 1997.
What Is Hoya Macgillivrayi
Hoya macgillivrayi is a fast-growing evergreen climber whose flexible stems can grow several feet long. It has thickened, leathery oval leaves of light green color with pointed tips.
The leaves in pairs grow opposite each other. A pronounced central vein on the leaves divides the leaf surface into two leaflets.
Small, fragrant, star-shaped flowers appear from early summer to fall.
The individual flowers are gathered in a cluster, but unlike other species, the Hoya macgillivrayi flowers grow on slightly longer stems, so they do not form a compact flower ball .
Each tassel-like umbel consists of 6 to 16 individual flowers with a total diameter of 2.5 to 3 inches. They are most often dark burgundy, but there are also cultivars with purple or red flowers.
Hoya Macgillivrayi Care
As an indoor plant, Hoya macgillivrayi grows best in heated greenhouses, where it can get enough of the light, moisture, and heat needed to thrive and bloom all year around.
Yet, it is not to say that it will not thrive even in standard room conditions since, with a bit of extra care, you can grow this fragrant decorative creeper like all other houseplants.
Hoya Macgillivrayi Soil
The key factor in growing Hoya macgillivrayi is choosing suitable soil since the plant is very sensitive to soil compaction and impermeability. If you want a lush, richly leafy plant, provide it with a peaty, crumbly, very airy, and well-permeable soil through which water passes quickly.
Hoya macgillivrayi is classified as a succulent plant, and you can grow them in ready-made cactus mixes. Even such soil should be further lightened with perlite to improve permeability.
You can also make a mixture of peat moss and perlite, to which you will add some chopped pine bark as Hoya macgillivrayi likes neutral to slightly acidic soils with a pH reaction of 6.1 to 7.5.
The frequency of watering Hoya macgillivrayi primarily depends on the type of soil in which it grows, and then on the temperature, amount of light that the plant receives, and, of course, on the season. Roughly, water it twice a week during the season of active growth if it grows in well-draining soil.
In the summer months, the water evaporates faster due to high temperatures. In such circumstances, if it grows in well-draining soil, your Hoya macgillivrayi may need watering every other day. Therefore, water as soon as the surface part of the substrate dries to a depth of 2 inches.
From mid-October, gradually reduce watering, and during the winter months, water it once a week or every ten days, just enough so that the substrate is not completely dry.
When watering Hoya macgillivrayi, do not use tap water as it contains active chlorine, which adversely affects this plant, especially if it accumulates in the soil for a long time. Therefore, always let the water stand for at least 24 hours before using it to hydrate the plant.
After watering, be sure to pour the excess water that has drained into the pot tray since the plant does not like sitting in wet soil.
In climate zones 11a and 11b, where the temperature does not fall below 40 F, you can grow Hoya macgillivrayi as a garden climber planted in the ground. In all other zones, Hoya macgillivrayi thrives as a potted houseplant, protected from low temperatures.
The lower minimum it can withstand is 50 F. At temperatures below that value, the plant first begins to shed leaves, and if the downward trend continues, it dies due to hypothermia.
Therefore, it is best to keep Hoya macgillivrayi in a space that is evenly heated throughout the year, with temperatures ranging from 70 to 85 F. The plant can survive even if it spends the winter in a slightly colder environment, but this will slow its growth and may result in no flowering.
One of the potentially demanding aspects of Hoya macgillivrayi cultivation is the high level of humidity in the air that this plant requires. The standard humidity of the space in which we live is mostly around 30 percent. In the winter months, due to heating, this level is even lower.
If you want to provide your Hoya macgillivrayi with a pleasant environment, you need to double the humidity level since it needs at least 60 to 80 percent during the day and 80 to 100 percent during the night.
At first, achieving such conditions may seem like an impossible mission. However, this is not so difficult because there are a few simple tactics to attain it.
- If you have enough space and lighting, place the Hoya macgillivrayi in the bathroom or kitchen because these areas have increased humidity levels.
- If you do not have the conditions to keep the plant in these rooms, or you want to enjoy your Hoya macgillivrayi in the living room, misting the leaves is a way to provide adequate humidity. Use stagnant water and spray the leaves every other day, best in the morning.
- Also, you can group multiple plants in one place. Such a small plant community always looks attractive and makes your job easier. You do not have to spray the plants in the group so often because the average group transpiration is usually enough to change the conditions in the immediate environment of the plants. In other words, the plants help each other, creating a system similar to the natural one.
- Finally, you have the option to get a humidifier with which you can regulate the humidity level, adjust it and change it according to your needs or seasons.
Like all other houseplants, Hoya macgillivrayi will grow better and bloom more abundantly if you feed it regularly. Feeding is an integral part of caring for this plant, even when it grows in high-quality and nutrient-rich soil.
Start feeding in March when the plant slowly emerges from the semi-dormant phase. Feed it once a month with a liquid fertilizer with an NPK ratio of 2:1:2 or 3:1:2. Fertilizer of this composition will improve the general condition of the plant, stimulate the growth of new and healthy appearance of existing leaves.
You can dilute the fertilizer to half the recommended concentration to see the plant’s reaction. Namely, too concentrated fertilizers can damage HW roots, so it is better to start with milder versions.
In May, feed your Hoya macgillivrayi with fertilizer created for flowering houseplants. Such fertilizers have an increased content of phosphorus that stimulates the development of buds and flowers.
Such fertilizer usually has an NPK ratio of 5:10:3, and you could use it as long as the flowering season lasts. When the plant stops producing buds, feed it once or twice more, and from late October to next March, stop feeding altogether.
If you prefer organic fertilizers, you can feed your Hoya macgillivrayi with compost tea or dilute fish emulsion, provided you do not mind the rather pungent odor that the emulsion has.
If you grow Hoya macgillivrayi in the house, make sure to provide it with plenty of light but never expose it to direct sunlight. Its thick leathery leaves may look resistant but still burn easily in the sun.
In nature, it is an epiphyte that grows on other plants sheltered from direct sun by the canopy of its host. Therefore, place it next to the east or west window to get at least six to eight hours of filtered daylight.
Light is a crucial factor for Hoya macgillivrayi flowering because without adequate lighting throughout the year, the plant will simply not bloom. In the northern hemisphere, when the autumn and winter days are short, indoor Hoya plants will need additional artificial lighting in the mode of 12 hours of light and 12 hours of darkness.
You could apply the same tactics when the plant grows in a space that is not well lit. If you do not please the plant and do not provide additional lighting, it might survive, even give the new leaves, but you will wait in vain to see its famous, umbrella-like flowers.
Potting and Repotting
Compared to the leafy above-ground part of the plant, the Hoya macgillivrayi root grows relatively slowly, so there is no need to transplant it often.
In addition, Hw belongs to those types of plants that grow better if there is not too much space in the pot. Therefore, even when planting the plant, do not take too large pots. In such a container, the plant redirects energy to root development and yields very few leaves.
Pruning Hoya macgillivrayi involves removing diseased or withered and damaged leaves and shoots to make the plant look neat and well-groomed. In addition, you can prune shoots that are too long to maintain the desired plant size.
- Always use sterile scissors or a knife, and cut the plant under the node.
- Pruning stimulates the growth of new shoots and makes the plant look more dense and attractive.
The simplest way to propagate Hoya macgillivrayi is top cuttings from an existing adult plant that you can root in water or directly in the substrate.
– Stem Cuttings in Water
- Using a sterile knife or scissors, cut off the top of the stem at least 3 to 5 inches long with at least two developed leaves and two or three nodes.
- Place the cuttings in a glass of water so that the leaves are above the surface.
- Place the glass with the cutting in a bright and warm place without direct sunlight
- Periodically add water as needed to maintain the same water level.
- Also, keep the water clean and make sure that no plant material prone to rot enters it.
In the next two to three weeks, the cuttings will develop a root. Depending on other conditions, the process may take longer. Keep the cutting in water until the new root starts to branch, and only then transplant it into a smaller pot filled with substrate and perlite in equal parts.
– Seed Propagation
In nature, light and fluffy Hoya macgillivrayi seeds are dispersed by the wind.The seeds quickly lose germination, so if you want to try growing Hoya macgillivrayi in this way, make sure you get fresh seeds.
- Prepare moist soil, which is a mixture of perlite peat moss and orchid bark.
- Distribute the seeds on the surface and then mist them carefully. Wet seeds will be easier to trample into the surface due to better contact with the soil. Optionally, you can cover them with a very thin layer of soil, just enough to hold them in place.
- Cover the pot with clear plastic because the seeds need a high humidity of almost 100 percent to germinate.
- The germination process takes 7 to 14 days, at temperatures of 70 to 80 F and constant humidification of the substrate.
- When the seedlings develop at least two leaves that you can hold in your hand, remove the cover and transplant the newborn Hoya macgillivrayi into individual pots.
Pests and Problems
In conditions of too high humidity in the soil or air, Hoya macgillivrayi can be susceptible to fungal infections, such as powdery mildew or sooty mold that form white, dusty clumps on its leaves or cause black-spotted leaves
To solve the problem, after removing the infected parts of the plant, you could treat it with copper or sulfur-based fungicides that you mix with water and spray the leaves with this solution.
Common house pests will not spare this plant as well as most others. These are most often aphids and mealybugs, and spider mites can also occur in dry air conditions. If they attack the plant, you could apply a neem oil solution or treat it with a mild insecticide for parasites on houseplants.
Why Doesn’t Hoya Macgillivrayi Bloom?
- Young Hoya macgillivrayi will not bloom no matter how well you take care of it because the plant needs maturity to bloom.
- In addition, the essential factor that stimulates flowering is the lighting that the plant receives throughout the year, not only during the growing season.
- Moving the plant from one place to another also adversely affects bud development.
Let us go over the general care and growing rules for Hoya macgillivrayi:
You can grow Hoya macgillivrayi in a greenhouse or at home in a hanging pot or a pot with support to which it will adhere.
- It thrives best in nutritious and highly permeable soil that dries quickly
- Keep the plant out of direct light, drafts, low temperatures, and large temperature oscillations.
- Water it moderately with lukewarm stagnant water and avoid excessive watering.
- Feed it regularly with liquid or slow-release fertilizer during the growing season.
- The plant does not like to move, especially when it blooms, which is why it can shed all its buds. Transplant it only when the pot becomes too small.
- In the end, let us say that Hoya macgillivrayi is a surprisingly resistant plant that will survive adverse conditions or neglect. Yet, the result of unfavorable conditions is not necessarily the decay of the plant but the absence of flowers.
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