Barb, that's a complicated question. Lots of variables to consider. Your biggest priorities are preventing rot, so depending on whether they are indoors or outdoors, and your climate, you need to select a growing medium that won't hold too much water. There really is no one answer to your question, it'll take some trial and error to get the right mix of organic and inorganic medium. I've included a link to a discussion on soils on an earlier thread on this forum.

Here is a link that might be useful: Soils

In terms of fertilizer I would make one suggestion. If you use a water soluble fertilizer and do not replant your amaryllis every two or so years watch out for salt build up. Most water soluble fertilizer can create a salt build up so when you do not water a plant so that the water runs out of it the salt will build up in the soil and can hamper the growth of amaryllis after two or so years. When in containers I would fertilize mine at least once a week or every watering with about one half to one quarter of the suggested concentration. The type of soil that you use will determine how often you need to fertilize but it is always safer to use a weaker concentration than the full concentration on most products.

I'm posting a link to a recent thread about potting mixes. It is quite long, and it has a ton of info about growing amaryllises in pots.

As for fertilizer, I really wish I could find some good info on that. The previous poster repeats what I have read is some of the best advice for feeding potted plants, which is "fertilize weakly, weekly." I've also read that some people give their potted bulbs half-strength fertilizer twice a month, which is what I've started doing this year. What I'd like to know is what are some of the best types of fertilizers to use in potted amaryllises? I've been thinking about starting a new thread on the subject, but it'd be great if I could get some suggestions here.

Here is a link that might be useful: The Naked Truth about soils

Thanks for your answers. I tried the Al's gritty mix and I have not been happy because of the poor water retention. I have about 100 bulbs, and trying to run around after watering them to empty all the trays is just too time consuming. Plus they have needed watering about every other day.

Two bulbs I missed emptying their tray actually had some slimy stuff at the base by the time I caught my mistake, and I have had one of my window sills damaged because of water overflow I didn't see.

So, I am now repotting all of them into a more water retentive medium- a professional mix for containers that has a lot of perlite. This mix is expensive, so I thought I would post here to see what other people are using.

A neighbor down the street just gave me 9 bulbs she had gotten this winter from WWF. I noticed they were in an organic type mix with a lot of perlite too. I don't see compaction, and I have decided to keep those bulbs in that medium and just water with a water soluble fert.

Trial and error......

Ryan in Denver, and myself, have been using a product called Hydroton. They are little clay balls used in hydroponic growing systems. They have been working very well for us. They absorb a lot of water, but then release it as vapor. The hydroton is never really "wet". They are like an unglazed clay pot, holding moisture, but not wet to the touch. I mix it with regular potting soil and it helps retain just the right amount of moisture without keeping the soil wet. You can find them on Amazon.com... or in any local hydroponic supply store.

Barb, try mixing a bit of vermiculite into Al's Mix for added help in retaining water...

I can't tell you how flattering it is to find one of my threads used as a link for informational purposes! I certainly hope someone is able to draw some good conclusions and useful information from it!

My medium of choice is, of course, mainly inorganic... it's comprised of pine bark particles, turface or granite chips, perlite, a bit of vermiculite, and occasionally a handful of quality bagged potting mix. I water from the top, leaching occasionally to remove any salt and mineral build-up, and the majority of my bulbs remain indoors all year long, with an eastern exposure and supplemental lighting.

Since I grow indoors, my bulbs are exposed to heat from the furnace in winter and cool air from the AC unit in summer... in other words, the temperature is rather consistent all year long. The only thing that really changes is the sun coming in the east facing window... in spring, the days lengthen... and in winter, they shorten.

One very important thing to remember is that a container environment is VERY different from a garden environment...

In the garden, there is a constantly working and self-balancing palate of worms, insects, nematodes, micro-organisms, bacterias and fungi... they are constantly breaking down the soil components, helping to keep it aerated, and digesting any organic materials which makes it available to the plants for food. That's one of the reasons organic fertilizers work so well in the garden... they have help! All this decomp and action keeps a balance of "good and bad".

In a container, we don't have those things... so it's important that the decomp be very slow, that the medium provides for excellent aeration and drainage, and that we carefully water and feed a fertilizer that is readily available to our plants for use.

I'm lazy indoors, and quite busy working outside for as much of the year as I possibly can... so I might re-pot my bulbs once every 3 years, or sooner or later depending on how they're growing.

For fertilizer, I use a regular store bought liquid for houseplants and I supplement with a micro-nutrient. Right now, I'm using Miracle-Gro liquid. It's better to keep a plant on a constant feeding schedule with a low dose of food than to risk burning the plant with higher doses less often... and so, I use a diluted mix of liquid food and water about every other time I water. I use the food at about half-strength or less.

When choosing a decent medium for your bulbs, it's important to think about where you'll be growing them, what the climate and environment is like, and how much time you'll be able to devote to growing.

Proper watering is going to play a key role in growing anything in a container. More plants are killed by over-watering than any other one thing!

Bulbs are very forgiving, and it's actually better to err on the dry side with Hippeastrums... if you're not sure you can feel moisture when checking the soil, it's better to wait until you're certain they're dry than to overdo the moisture... while the soil surface my feel dry, the actual area around the root ball may be plenty moist. And since Hippeastrum bulbs are prone to rotting in a poor environment, it would be better to make certain the bulb needs a drink.

My pot of choice is an unglazed clay one... the material is porous and allows for "breathing"... the porosity also allows excess salts and minerals to exit, collecting around the outside of the pot. It can be wiped away and the plant leached with plenty of clear water.

I will use plastic pots if I have no other choice, but I try to re-pot into clay as soon as I am able. I find that plastic holds too much moisture for too long in my particular environment.

I think I've answered all the questions asked in the original post... but if I missed anything, please ask again! I'd be happy to share my growing methods, and perhaps something I share will be usable information for someone!

We all have to take into consideration our climate, the environment we can provide for our bulbs, and what materials will be available to us. Hippeastrum bulbs are very resilient, but the better we care for them, the more rewarding they will be!

Happy Gardening!