IMHO there is not working magic or a "secret compound"
Prepare a bed, with heat mat at the bottom and 30 cm height of best, loose substrate, OR use BIG community boxes,
In a greenhouse (light incoming from all sides) you be capable of reproducing these results. Within a bed there is some slightly better and inferior places,for exampe "dry patches" that unnoticedly receive less water from the automatic supply system - and at the end of the season the producer will harvest bulbs of different sizes. After grading, the supersized bulbs will be sold as such.The biggest bulb that I ever had was 50cm in circumference, in 12 L pot (cluster w/ plenty of daughter bulbs) and it would produce 4 scapes (this happened at an exceptionally good location in the laboratory where I used to work. That thing would produce leaves of 150 cm in length this was awesome!

WOW Hans, what a lovely picture you painted, I would love to know more about the subject of commercial growing! Are many cultivars able to grow this size or just large polyploid hybrids like 'Red Lion' or 'Naranja'?

Josh

The phenomenon of supersized "mother" bulbs 40+ cm (not that they are actually "Mothers" although I don't doubt that they might become "mothers of amaryllogenous appreciation")is AFAIK confined to the "common" TET Hippeastrums. However, some TET- or DIP- Hybrids with H.papilio parentage might produce big bulbs too.

Of "Ambiance" (a TET or a Triploid?) I have one daughter bulb grown up to, a ver... 38 cm, and my MOTHER bulb (now a real mother) of PapDonAmb2 (a DIP) measures 37.5 cm now. ALTHOUGH, for unknown reasons, my Hippeastrums do not grow quite as well as they used to do in my previous location. Bulbs with H.cybister- and "Chico" heritage respectively can become rather large too, DESPITE their rather small leaves.

Contrary to the philosophy of HADECO, that they published online, to produce Hippeastrums with small bulbs that still produce an Abundance of flowers, I always APPRECIATE big bulbs as a good, sound basis.When I have to select seedlings that are just 1/2 years old, I always look for specimens with conspicuously BIG bulbs. I discard seedlings with big leaves and a small bulb, particularly if the bulb has but FEW leaves. Lots of leaves do at least promise "lots of scapes"(on a mature bulb)

NOTE that a giant bulb does not automatically require much space on your windowsill.Neither does a fan of MANY leaves. Giant leaves, such as being produced from "Appleblossom" "Orange Sovereign" and the (original version of) "Melusine" is ACTUALY, that make a specimen consume abundant space in sometimes inconvenient ways.

Commercial production of bulbs CONSIDERS the point of the Costs for Transportation PER BULB. So it does not surprise me that they are NOT inclined to create hybrids that have "High bulb weight per total number/weight of flower output"

Great information.

I recently planted a bulb for a variety called "NARANJA". The bulb was the size of a cantaloupe, and probably weighed over 3 pounds, easily. I had to plant it in a 5 gallon pot. The bulb was over 6" in diameter, so it needed all the soil volume. The bulb was sold by Blooming Bulbs. Pricey....

BronxFigs

Every living thing is a combination of genetics and environmental stimuli... my best guess is that jumbo sized bulbs are a result of combined heredity, age, and extremely good environmental care. They've been grown in the best possible conditions, and have had a little time to gain such girth.

The trick will be keeping that girth and encouraging further growth in a home environment.

I've had the opportunity to grow an average sized hybrid Hippeastrum bulb to jumbo proportions, and I've also had the opportunity to begin with a jumbo sized bulb.

The bulb I grew to large proportions is a Minerva, a very common hybrid variety available almost everywhere. I believe I was lucky enough to receive a very genetically strong and healthy bulb. Through many years of intermittent care and neglect, it has thrived, producing offsets, blooming, and growing to very large proportions within its container environment.

The other bulb is a jumbo Red Peacock. Treated in the very same manner as the Minerva, grown through bouts of good care and bouts of neglect, it has seen fit to shrink a bit over time. With better, more consistent care, I know it might have retained its jumbo size, and quite possibly have grown larger.

I concur with Haweha, in that commercial producers have an interest in anything that will amount to a larger profit line... therefore, aiming to produce a bulb that weighs less and will cost less to ship, not to mention take up less container space for shipping, while still delivering a decent amount of bloom, is the logical direction to take. As a corporation, they probably have stockholders to satisfy, and the larger the profit, the happier the investors and company management.

Personally, I'd rather have the larger bulbs, and I think it's worth it to pay a little more for them.

It is not only about them flowers that we grow our Hippeastrums. Nice, fat bulbs, and bulblets, that appear like voluptuous, shiny Eggs, saturate our Dopamin (satisfaction) Receptors, too!

Thank you all you are all amazing, I will soon share pictures of my hippeastrum's, that's what I lack sharing pictures!

In a way, I suppose it is like a drug addiction, satisfying the pleasure sensors within our brains to some small extent. It certainly is pleasurable to work with our bulbs, and see the results of such work show in the spectacular blooms they produce! There's always that need to add more bulbs to our collections and see more blooms, hoping we don't get carried away and run out of space to keep them!