There are different ways to grow hoyas and other tropical plants, and everyone has to find the way that works best for them. I'm going to share with you the way that works for me.
Most hoyas are fairly typical of epiphytes: They grow wherever they can get some grip on the host plant. We usually grow them in pots, so it's important to remember that in the wild their roots get a lot of air and their host supplies humidity. As growers, we have to do our best to replicate their natural environments.
When I see something going on with a plant that I don't understand (leaves are funny, vines are dying back etc.), my first action is to tip it out of the pot and check the roots. It normally doesn't hurt the plant, but it does give me an idea of the overall health of the plans.
Clay pots are lovely, but there is a big drawback to them: when they dry out they kill the fine sensitive roots that are clinging to them on the inside. Watering can cause those dead roots to rot and the plant will then decline. I find that plastic pots are much better, or ceramic pots that are glazed on the inside.
I have experimented with many types of bagged mixes and have finally settled on mixing my own. It’s never the same from batch to batch because I do not have a recipe and I don’t use a measuring cup. I mix for my particular needs: My stock plants grow outdoors and it rains about 170” per year. So, I need a mix that lets the water run through, yet it stays damp with the bark. For the plants that grow under the eaves of the house, I mix a bit more organic matter so that it doesn’t dry out so fast.
For the most part, hoyas grow where they can get a root hold in the crotch of a tree, or in a mound of debris not occupied by the roots of something else. The key to growing them in containers is to make the mixture fast-draining with organic matter and prevent the soil from getting soggy.
My take on different elements in making a good mix:
Beauty Bark/Orchid Bark (fine)
-- The bark provides organic matter, holds moisture, and provides good drainage. I love it.
– I use #3 (bigger) for my potting mix and #2 for my starting mix. Perlite provides excellent drainage, but it does break down over time.
-- This is wonderful stuff, but it is hard to find. It does not break down, it provides good drainage, and it is organic and naturally slightly acidic. Red cinder contains a lot of iron and is NOT a good growing medium.
-- I used to be a firm believer in Coir. However, a bad batch of fertilizer with excess salts and cool damp temperature, plus the tendency of coir to reabsorb salts in the medium, led to disaster. I will not use it now and I stick to Orchid Bark.
-- This dries out quickly and rewets slowly (if at all). I avoid peat.
My basic recipe
: I use 1/2 #2 or #3 Perlite and 1/2 fine bark (usually sold for landscaping). I propagate in GrowStones and/or Hydroton, so I throw a bit of that in as well. Both retain moisture well. I also add aged chicken manure or fish meal to the mix. Not a lot, maybe about 5%.
My test of the potting medium is to get it really wet, grab a handful and squeeze really hard...then drop it from about a foot high. It should fall apart and not land in one wet clump.
No groups of plants have synchronized water needs, much less hoyas of various sizes and leaf shapes. Contrary to folklore, hoyas do not need to dry out completely between waterings. They are not arid plants. In fact, they come from the damp, moist and humid tropics and subtropics, or from misty mountains. A few hoyas are considered to be succulents, but even they can be watered more than once a month.
To see whether a plant is dry and needs water, I press on the soil in the pot. If there is a give to it, it is still moist. When it is dry, there is no give and it feels different. In the case of larger plants, I go by the weight of the pot. My soil mix allows the water to moisten the planting medium, but also to run through it. Nothing stays soggy. I water my plants heavily, not just giving them sips. If you can keep the humidity high around the plants, the moisture of the soil isn’t as critical and you can skip a day or two. Putting potted plants on trays of pebbles and water helps. Note that the water in the trays needs to be replenished often. Grouping plants together also helps raise the humidity factor, and so does spritzing your plants from time to time.
If you cannot collect rain water, or if you don’t have a well, it’s a good idea to let your water sit overnight before using it. The chemicals added to our city water can evaporate and flash off. Fluoride, for example, can kill some tropicals quickly.
Generally, most hoyas and other tropicals thrive in indirect bright light. Think of a forest and the light on the tree trunks.
Mealies, mites, scale, and aphids are all Hoya pests. There are others, of course, but these four take up most of our time. Keeping ants controlled and off of your plants will help. Keeping them spritzed also helps because mealies don’t like being wet. Know what these pests look like so you can stop them before you have an invasion! Keeping the plants healthy is most important. Pests look for weak and sick plants to prey on. If a mild invasion does occur, spray the infected plants with alcohol (straight, undiluted), This dries up the mealies. If you have a major invasion, a good drenching with a systemic insecticide containing Imidocloprid will do the trick. Imidocloprid does not smell, it will not gas you, and it will last from 6 to 12 months. You can also mix a mild solution of dish detergent and dunk the whole plant in a bucket of the solution. This won’t hurt the soil, but do run clear water through it afterward.
How do you know if your plant is ready to be repotted? If your hoya is in a plastic pot that you cannot squeeze even a little, it may be ready to pot up. If it is in a dish, and the roots of the plant are traveling down into the moisture in the dish, it could be time to pot up.The major problem with being too root-bound is the inability of water and nutrients to get to the roots in the center.
I have been told that a very successful grower, Cathy Perpich, grew many of her hoyas in shallow baking dishes (about 3” – 4” deep). I have been very successful with wide but shallow planters (about 16” x 6”) for my big hoyas. You will see, when you unpot the plant to repot, whether it has shallow or deeper roots. Repot accordingly.
One big urge to ignore is the inclination to move your hoya to a bigger pot. I did this about 30 years ago with my first hoya and it didn’t put on any new growth for almost a year. When I changed it and crowded it into a smaller pot, it hit the limits of the pot and put on top growth. I think of it this way: The plant has a natural survival instinct. When it is getting a toehold in some tree or on some limb, it wants to know it is safe, and so it puts out roots until it reaches the limit of its environment. It can then put out growth and start to climb.
I hope by sharing some of my techniques I have encouraged you to expand your houseplant collection!