I would say that you need to get your bulbs outdoors for the summer! But, if you can't, I would definitely think about changing the medium they're planted in!

My thoughts on this are that because there is no natural light, there's probably not a lot of air circulation, either... in which case, keeping your bulbs planted in regular potting soil is not going to be healthy.

I've attached a link at the bottom of this post... please read the article written therein. It will completely explain how container soils and water and root systems work together, and if you change your soil to the recommended mix, I can almost guarantee that you'll have better success.

As for the lighting... I use supplemental lighting for my bulbs, but they get natural light, too.

Here is a link that might be useful: Container Soils - Water Movement & Retention V

At least artificial light out of high pressure metal halide discharge lamps is suitable as only light source - without the slightest supply of natural (sun) light.
Provided at sufficient area related power, for example 200 Watts per square meter from modern lamps whith cool white 3-band spectrum(4000K, 100 Lumens/Watt) or daylight spectrum (5600 K, 80 Lumens/Watt)you can raise seedlings in two seasons (mainly progeny out of the smaller diploid cultivars) and three seasons, respectively (progeny from TET cultivars where the first floret is generally initiated firstly in seedling bulbs of at least 22 cm in circumference).

However, Gerard, I am rather well aware of the problem you have experienced and at least do I think so, respectively because I used to have similar damage.
Particularly in the winter months, I observed that some bulbs stopped growing, and I discovered the majority of them roots where rotten and the base of the bulbs was seriusly affected too. Since I could not detect tarsonemid mites or better let's say not more mites than usual I had to conclude that the damage had been caused primarily by fungus, and my presumption was Fusarium oxysporum (ssp. I dunnowhat) or, alternatively, it was a secondary infestation after tissue damage effectuated by parasitic nematodes Pratylenchus scribneri or another Pratylenchus or Paratylenchus species...
Assuming that the primary reason WAS a worm, I tried to cure the milder affected bulbs and the crop just when I perceived the first suspicious signs (slower growth) by applying Dimethoate (1 mL/L) with the water (I appkly water but from below, into the saucers, every second day, and I repeated the treatment once (with the next watering. And actually, this worked.
On the other hand it has to be stated that Dimethoate is not intended to be used in rooms where people are living in. And, it is rather odoriferous - but that is not the problem when you administer water from below; the very special "scent" disappears rather fast in this case.

Hey guys...

Thanks for your feedback...I've read and digested a bit as well as have done a bit of research.

Jodik: after reading your response and reading the article you directed me to (thank you :-) ), I've come to realize that the potential for waterlogging most certainly has played a role in the weakening of my plants. However, upon looking up the specs of the mix I use on the web, it seems to come CLOSE to what the guy in the article recommends for a mix. The only difference I'd say though is that there might not be enough bark in it and it does use peat moss instead of sphagnum moss. Because most of my Amaryllis are growing in clay pots with only one drainage hole out the bottom, I realize that I have to be VERY careful how I water. The reason I use those pots though is because of their porous walls and hence the water should evaporate faster through the walls allowing the soil to dry out faster etc. As for getting the plants outside, I dropped the ball this year as I wanted to take them to a friends place and have them situated on the south facing side of his house. Unfortunately, in early June this year, the weather was not conducive to having my babies outside...too cool.

Hans:

Thanks for your feedback re: the lights and using Metal Halide. Correct me if I'm wrong but it appears you're suggesting that I don't need much if any additional sunlight if I switch to the metal halide which I can (I have a bulb that can operate on a High Pressure Sodium ballast etc). This particular bulb is rated as a Neutral Deluxe and it indicates on the package that it throws out light in the 4000K range of wavelength which closely imitates natural sunlight.

Re: using dimethoate for potential insect problems: a. I cannot get my hands on any as it has been taken off the market here as of about 5 or 6 years ago and b. it would stink up my apartment something fierce :-). I suspect that my problem is not insect related but water related ...i.e. possibly too much and not good enough drainage etc.

So I will attempt to fiddle with the drainage issue but I suspect I shouldn't have to change my soil BUT I should watch my water more closely i.e. not give as much or allow the plants to dry out much more and maybe change back to using this metal halide lamp and see how that goes.

If I can swing it to get my babies outside in good light during the spring/summer, I'll do it in a heartbeat as I've done that before and have had EXCELLENT results.

Thanks again for all your help.

Gerard.

I use clay pots, too... I feel that the clay is much healthier because it "breathes", and excess salts are able to leach through the walls, to some extent. Drainage holes can be one or many... it really doesn't matter... perched water tables being what they are. I used to think that a layer of gravel or charcoal was necessary for good drainage... but now I know that it's actually bad to use a layer of anything, and better drainage occurs when there is only one medium layer throughout the entire pot.

The problem with bulbs is that they are prone to rot from too much moisture for lengthy periods of time. Improper watering is responsible for more plant deaths than anything else... and so, if you couple a very well-draining medium with careful watering techniques, you can successfully avoid rot. Most soils decompose quite quickly, and as we water them, they compact. If we can slow down the decomp, and slow down the compaction, we can have healthy roots.

The medium I use is very close to what I see sold in stores as "bonsai mix". Al's Mix is comprised of slightly larger particles than found in most mixes, and it doesn't break down very fast at all... I have found, though, that I must water a little more often, but I'm ok with that. Using Al's Mix, I top-water... when I had my bulbs planted in regular potting soil, I had to bottom-water in order to keep the moisture where the roots are situated in the pot.

When I posted my initial response yesterday morning, I hadn't had enough coffee to think clearly! It's entirely feasible to grow plants using artificial lighting only... as long as you keep good air circulation flowing, have the proper type of lights, and take care when watering and feeding. Plants grown in isolation also require CO2, I believe it is... the root systems require an exchange of oxygen and CO2 in order to be healthy. That can be done artificially, too.

I also think it's important to note that growing in containers is a whole different environment than growing in a garden... gardens have worms, nematodes, good and bad bacterias... and a garden ecosystem is balanced by all these things. A container environment can quickly become unbalanced because there isn't that constant "flow" of good and bad going on that creates the balance. I hope I explained that well enough...

It's difficult enough to consistently grow healthy plants in containers, keeping a healthy balance of moisture and other root requirements... proper medium and proper watering can help immensely!

Of course, it will always be better to grow with natural light and fresh air... but done with care, healthy bulbs can be grown successfully by artificial means.