By: Bonnie L. Grant, Certified Urban Agriculturist
Wax plants make terrific houseplants. These easy care plants have few special needs but they do like to be fed. Hoya growth will take off if you have a regular feeding schedule. There are two schools of thought on when to stop fertilizing a wax plant, but almost everyone agrees they need supplemental food during the growing season. Find out when to fertilize wax plants and enjoy these indoor beauties for years.
Hoyas most likely originated in India. There are at least 100 species, many of which produce marvelous bloom clusters. Most growers find them to be unfussy little plants that simply need average light, warm interior temperatures and regular water. The best performance can be achieved with a regular feeding program. This will fuel growth, enhance health and increase the chances of some of the beautiful blooms.
Hoya fertilization can take place year round. However, many growers feel the plant should not be fed at all in winter, while others do a half dose of liquid fertilizer in the cold season. Feeding the plant in winter may cause an excess buildup of salt in the soil, so if you do feed then, make sure you leach soil occasionally.
A liquid based plant food is most typically recommended for fertilizing a wax plant. It is easy to apply and gets right to the roots where the plant can uptake nutrients. Once per month add the food to the irrigation water and apply to the soil around the roots. Time release granules are an excellent choice for Hoya plant feeding. They will slowly add nutrients to soil so you don’t have to remember to fertilize for months.
The nutrient ratio listed on the plant food should have a higher nitrogen content since Hoyas are primarily foliage plants. Any food with a 2:1:2 or 3:1:2 is sufficient to keep the plant in good health.
For wax plants that are flowering, however, switch to a 5:10:3 with a high phosphorus number to encourage blooming. Use a high phosphate fertilizer for 2 months prior to the plant’s normal blooming time. That will fuel the plant to produce more profuse and larger blooms.
Once flowering starts, go back to the high nitrogen food. Plants that are in low light areas will typically need half the food as those in full, indirect light.
Choice of feed and timing are important but you still need to know how to fertilize wax plants. Most fertilizers will give instructions on the amount to mix with water or to add to soil if using a granular preparation.
Professional growers recommend a rate of 2.9 pounds (1.32 kg.) of nitrogen per 1,000 square feet (305 m.) but that isn’t helpful if you just have a couple of plants. Liquid foods often have a measuring device to show how much to add to a gallon of water. Granular foods will also have a method of measuring.
If all else fails, consult the back of the product and it will tell you how many units per gallon to mix. Deeply water in any liquid food and also water deeply when using a granular time release formula. This gets food right to the roots but helps prevent buildup in the soil, which can harm the plant’s health.
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Read more about Hoya Wax Plant
There are over 100 known species of the Hoya plants. Hoya Carnosa, on its own, has some strictly identical cultivars like the Hoya Carnosa Rubra and Hoya Carnosa Variegata. They assume different leaf shapes and flower colors. But then the main focus is on the Hoya Carnosa, which has Large Dark Green Almond-Shaped leaves.
It is a succulent, vine family plant or merely a climbing type. It has thick almond-shaped dark green succulent leaves, which are distributed one leaf per node. The flowers create clusters of circular-shapes of varying star-shaped flowers. And those colors range from dark pink to near-pink.
P Hoya macrophylla needs plenty of bright light in order to thrive. While it won’t mind medium light or even low light conditions, the latter can cause its growth to slow down.
That said, you want to keep it under indirect or filtered sunlight. Avoid direct sunlight.
While it won’t mind 2 to 3 hours of direct sunlight daily, it cannot tolerate long hours under this condition. Similarly, it won’t be able to take hot summer or peak afternoon sun.
Indoors, this means keeping it away from the sun’s rays.
East-facing window. Here is can take a couple or so hours of sunlight in the morning. But, not a lot more than that on a regular basis.
North-facing window. If you live in a warm, sunny region, this amount of light from here may be enough to keep it happy.
West and South-facing windows. Keep it a few feet from the windowsill. Or, place some kind of curtain or blind to filter some of the sun. You want to be aware of direct sun in these locations because the afternoons can get very intense.
Your Hoya macrophylla likes temperature conditions that are similar to what humans enjoy. This means there’s no need to do anything special if you keep it indoors.
Its ideal living temperature runs between 65 and 80 degrees Fahrenheit. And, it is not particular fond of extremes. Although, it is better able to tolerate hotter climates than it is cooler ones.
In the winter, it won’t mind if the temperatures go down to between 55 and 60 degrees.
It is hardy to USDA zones 10 and 11. So, if you live below region 10, you’ll want to keep it in a container so you can bring it outdoors during the summer.
However, if you live in a cooler region where it freezes during the winter, it is a good idea to bring the plant indoors before the temperature drops below 55 degrees.
The plant is actually more particular about humidity where it prefers high humidity. But, it can tolerate medium to a little lower humidity.
In most cases, it will be able to adapt to indoor household humidity without any problems. But, if your home is particularly dry, it is a good idea to mist it a few times a week or give it a shower under the sink.
This will help keep it happy.
As such, while is does best when humidity is over 70% or more, as long as you keep household humidity to 40% or higher, it will do fine.
On the hands keeping humidity really high, even over 90% will keep it happy.
In it native habitat, Hoya macrophylla grows in tropical conditions and doesn’t get a lot of rain. This means that is it better off with less than more water.
Also, it is important to keep in mind that the plant is epiphytic. So, it lives in the forest clinging onto bigger trees and larger plants. It also doesn’t grow in soil. Instead, its roots absorbs nutrients from the air.
As such, you want to mimic these conditions.
To do so, allow the soil to almost dry before watering. This is very important because it is susceptible to overwatering. And, keeping it in this condition will eventually lead to root rot.
Instead, always be mindful of how wet or dry the soil is. Regularly checking the soil, especially before watering ensures that you don’t water when the soil is still moist.
I always like to stick my finger into the soil. In this case, you want to feel that between 1 to 2 inches beneath the surface, the soil is dry before watering. If it is moist in any way, wait before testing again.
In the winter, scale back on watering.
When you do water, water thoroughly. The goal being to allow water to soak the root ball so it reaches the bottom. Thus, slow watering is best since dumping lots of water will cause it just spill down the sides of the container through the crevices between the soil and pot.
Once the plant starts dripping, stop watering and allow it to completely drain. Don’t return the plant to its spot if is still dripping at the bottom. You want all the excess liquid to come out.
This way, you’re sure the plant isn’t sitting in water.
Since it cannot tolerate wet feet, well-draining soil is best.
Similarly, its epiphytic nature make sit prefer loose and well-aerated soil. This allows air to pass through easily to get to the roots of the plant.
It also enjoys mildly acidic to neutral soil. Thus, soil pH levels between 6.1 and 7.5 are best for it.
As such, using a combination made from the following recipe works.
This lets you create an easy do-it-yourself potting mix. The perlite allows it to retain moisture so that plant is able to stay hydrated. It also keeps the potting mix slightly acidic.
The perlite provides the looseness and moisture draining ability.
Similarly, using a terra cotta or clay pot allows some of the excess moisture to seep out of the container because these are made from porous materials.
But, if you’re already using well-draining soil, you always want to observe how the soil and plant respond.
Using clay pots can sometimes cause the soil to drain a little too quickly. And, I’ve had to revert back to plastic containers for some of my plants, which provided in better results.
So, do test and observe. Then adjust.
You don’t need to feed your Hoya macrophylla a lot. It isn’t a heavy feeder.
So, applying fertilizer once a month is enough during its growing season. Make sure to dilute it to half strength or even quarter strength.
Like water, you want to be care full about giving it too much. Overfeeding can result in root and leaf burn. That’s because plant food leaves salt residue. And, over time this buildup is harmful for your plant’s roots.
Thus, you don’t want to use cheap fertilizers which leave a lot more salt and minerals.
If you do (to save money), make sure the flush the soil on a regular basis to get rid of these salts.
As with other hoyas, the macrophylla is low maintenance when it comes to pruning. Outdoors, the plant will easily grow to 12 feet or even longer. Indoors, it is a little more contained to about 4 to 6 feet in height.
But, its vines like to climb or trail. As such, you don’t really have to mind too much about their length in these conditions as they look better with a little more size.
That said, pruning helps keep them in check. It also lets you control the shape of the plant based on how you display it.
If you see some stems get leggy, trimming is a good way to fix this problem by allowing fresh growth to start over.
You also want to get rid of dying, yellow or damaged foliage.
Spring and summer are the best times to propagate the plant. You can do so when you prune it.
This will let you do two things at once since you’ll be trimming stems anyway when you prune.
Stem cutting is the easiest way to propagate Hoya macrophylla. And, it works quite well.
As the plant grows, you will need to repot your Hoya macrophylla between 2 or 3 years.
One basic rule here is if you don’t need to move it, leave it alone.
That’s because it doesn’t mind being root bound. Similarly, it is not a fan of being moved.
So, the only time you’ll need to repot is when it is crowding the container. This often means a few things.
According to the ASPCA, hoyas are not toxic to cats and dogs. This means you can keep them near animals. It is likewise not poisonous to people.
But, like all plants, ingesting any part can cause choking or other issues than can result in vomiting or discomfort.
In most cases, you won’t likely experience any problems with your Hoya macrophylla. But, they can be attacked by pests once in a while.
The most common of which are mealybugs. You may also see aphids and spider mites as well.
Each of these are different. But, they all cause damage to your plant in the long run.
You’ll likely see their damage in the form of yellow or curling leaves as well as brown and yellow spots on foliage. As they get more nutrients by sucking on the plant’s sap, it negatively affects growth even if you give it enough sustenance as it is being robbed of it.
As such, you want to get rid of pests as quickly as possible. Isolating the affected plant is likewise important because pests can move to other plants as well.
Treatment often consists of spraying with insecticidal soap as this allows full coverage. In contrast, trying to wipe or remove one pest at a time is tedious and time consuming.
When it comes to disease, overwatering and letting moisture site on leaves are the biggest culprits.
This can lead to root rot as well as other diseases.
Mold and fungus are likewise problems due to the plant’s love for humidity. Excess moisture, be it from the environment or man-made (watering and wetting the plant) can result in these problems.
As such, always be mindful of wetness. And, keep the plant somewhere there is good air circulation. This will help excess moisture dry faster.