There are a few ways to feed hoyas and many choices of products they seem to respond to. The easiest and fastest method is foliar feeding or misting. This can be accomplished using a regular spray bottle, small manual pump spray bottle or a garden hose using an injector filled with full strength fertilizer. I have used each method and I find the easiest and most accurate method to be the Pump Sprayer. Mixing is a cinch, and for me, pumping is much easier than squeezing since it takes quite sometime to be sure each leaf of my collection is wet.
The other way to feed is through drenching the roots or just watering the fertilizer into the mix or soil. I choose to use collected Rain Water, weather permitting and when the barrels are dry I use my Tap Water which has all of the chlorine removed using a Whole House Purifier.
These are the feed choices I use regularly or have used in the past and some quick thoughts on each. They are in no particular order and I have provided links to the products when available. I presently offer the MSU in a 8oz. size for convenience.
FOLIAR FEEDING or DRENCHING
Fish Emulsion - 1 teaspoon / gallon of non-chlorinated water - smells bad but the plants love it - use with EM-1 and the fishy smell seems to lessen
Humax - 1 teaspoon / gallon of non-chlorinated water - used to strengthen the root system - I use this in conjunction with other fertilizers
MSU - 1 oz. / gallon of non-chlorinated water - promotes green growth and blooms - a weak feed that can be used at every watering
EM-1 - 1 oz. / gallon of non-chlorinated water - a soil conditioner that provides living organisms to the plant - I use this in conjunction with other fertilizers
Grow & Gain - 1/2 teaspoon / gallon of non-chlorinated water - promotes green growth and blooms
Blue Mountain Organics - Flower Power - 1 oz. / gallon of non-chlorinated water - Bloom Booster - relatively pricey if you have a large collection - first season I've used this one - living organisms
Blue Mountain Organics - Grow it Green - .5 oz. / gallon of non-chlorinated water - first season I've used this one - living organisms - NPK 5-2-5
Blue Mountain Organics - Super Plant Tonic - 1 oz. / gallon of non-chlorinated water - good for starting out cuttings and reviving plants that just seem to 'sit there' (not for foliar feeding)
Superthrive - 1/4 teaspoon / gallon of non-chlorinated water - a carbohydrate for your hoyas - a must for soaking cutting just prior to potting them up for rooting
Compost Tea - use home grown compost or organic store bought soaked in water and sitting in the sun for a few days - I mix a super strong tea into my rainbarrels just prior to watering the hoyas each week during the summer months