This is something that happened to me over the course of years, mostly dabbling lightly with 2-plant combos sporadically and periodically over the past 15 years or so, then much more heavily into combos of up to 15 plants over the past few years, so I perfectly understand how odd it may sound to those who haven't considered doing it, or have no idea what to do. And am absolutely NOT saying there's anything wrong with any planting that has only 1 plant. I do still have several of those, and not every eye appreciates the wilder side of things. I am not saying anyone who currently isn't doing it should combine their plants if they don't already want to, or have doubts about it going well. Just providing some thoughts for those who are interested. I believe plants pick up our vibes, and that doubt often leads to failure, so should be respected if one is feeling that way.
For those who don't repot plants every year or 2 anyway, creating a combo with 1 plant that grows a lot faster than the others could be frustrating, but I do repot often and change partners/combos as necessary when doing that. (Or just take cuttings to share with others, if there's too much mass before it's time to repot.) I never go into a combo assuming the same plants will always be partners, just that I think they should be for the next year, and sometimes just for over winter (then to be put back in the ground for summer.) Trying to decide a combo for the rest of the plants' lives is daunting, I don't put that much pressure on myself.
At this point, I don't have a choice about combining plants, unless I want to get rid of more than half of them. I managed to consolidate into about 10 less pots this summer, for a total inside at the moment of about 80. There's no way I could find space for another 150 or so pots, and I know from experience that I don't get along well with small pots. Too clumsy, I knock them over so often, the plants rarely survive that experience at my house.
Combining has really helped me a lot, I think, since I tend to overwater plants. I don't think my technique has improved that much, and attribute the now rare death of plants to enjoying their combos. A packed pot dries much more quickly, and it can get pretty cold in my house, down to 50-55, which can cause plants to stay too moist forever if there's not a lot of plant mass (either from one plant being very large, or because there are multiple individuals sharing the space.)
Everything from Philodendrons to Opuntia are all in the most airy, chunky, porous mix I have available when repotting. I can't add dry, or cause drying to happen more quickly by doing something/anything to plants, but I can add water as often as needed. Since I use the same stuff in the pots for all plants, sun exposure is the main thing I use to choose plants to combine, and whether or not they appreciate drying out or would prefer to stay moist. Once those things match, it's just a matter of choosing those that use different 'air space,' and I do a lot of purposeful sideways leaning, instead of everything going straight upright.
Most plants are either upright, or dangling, leaving a lot of unused space if potted alone. When combining the 2 types, one gets the most use of the space each pot takes up, especially of concern for those of us who have to bring them inside for winter, and don't live in huge houses. Also, as said, I just like the look of 'mini jungles' and the more I do this, the more I develop a dislike for being able to see the soil at the surface of any pot. Not because it's inherently unattractive, but I just see 'empty space' where more plants could be.
Since using the plan of "stick it wherever it will fit in an existing pot" for about any/all cuttings, the success rate has gone up even more. With an existing root system of other plants surrounding a cutting, the worry of the cutting rotting before it can populate a pot with roots is eliminated.
I've uploaded a decent number of multi-plant pics, mostly potted plants. They also show up on the individual plants that are labeled. If folks look at the plants they have in the database here, they may see a combo pot below the single-plant pics for that entry.
About your specific combo question, IDK anything about Crotons, except that I can kill one as fast as anybody, and haven't brought one home to death row for about 20 years. I do have 4 Hoyas, but haven't had them around long enough to give much combining advice about those in particular.
This is one I've had for about 18 months, H. curtisii. Its' habit is to go straight over the edge, no height at all. By this spring, it was mostly naked on top, leaving a lot of vertical empty space in its' pot, so I added cuttings of Begonia, Epiphyllum, Easter cactus, Tradescantia cerinthoides, at various times, and a couple weeks ago, a few last pieces of Coleus that I'd like to try to save until spring. This pot is way too small for this to last long, but should be OK until spring. Sorry these pics aren't great, it's hanging slightly above eye level.
Plants that I don't think need a partner, at least the way I have them planted...
- Giant Aroids like shrubby & tree Philodendrons, Monstera deliciosa
- Heart-leaf Philo vine, just grows so much faster than any other vines I have
- Tall Sansevieria - too tall to hang, leaving insufficient space for a dangling partner. They also take over the entire surface area so quickly.
- Callisia fragrans - very successful at using vertical AND dangling space. But, I have started experimenting with sticking pieces of this in the sides of hanging pots that I add holes to. Can it be
just a dangler? IDK, but will see...
- Parlor palm, same as Sans, would need a pedestal to use a dangler, and also very dark under these, and they already go in my most shady spots.
- Billbergia (queen's tears.) Had for about 13 months, starting to see that its' pups are going to come up under/through/on the other side of any partners, and possibly push them right out of the pot. The Cryptanthus I put in the pot with this will need a new home in the spring (if the romance even lasts that long.)
