Hope you don't have the dwarf variety.
The 6 ft tall description is optimal growth in perfect condictions. And even though they claim they don't need staking the stalks are not completely upright. They do lean a bit.
You can try using a liquid fertilizer weekly and water well afterwards.
Read your Osmocote bag. It depends on what formula you have as to how long it will last in your temperture.
The hotter it is the less time it lasts.
You also need to deep soak at least once a week to get the fertilizer down to the roots.

Here is a link that might be useful: Alpinia zerumbet variegata

My potted alpinia are several years old and had not flowered. I must have dwarf. If you want them to serve as part of privacy fence try elizabeth. They grow tall and multiflies fast. Bellie

I planted 2 in May. They are not dwarfs and they are spreading rather than growing vertically at this point. They are currently 3 foot tall x 2 foot wide. They are planted in ideal conditions regarding sun/shade. I am just wondering whether they will take 6 months, 1 year, 2 years to reach mature height? And what can I do to maximize their growth? I have begun deep watering wekkly.

Hi Hal,

I have a large stand in full sun that are between 7-8 ft tall, crazy healthy with inflorescences on nearly every stalk.

My methods are not at all what is recommended but I have adapted because of our different soil/climate. Started with CLAY soil, amended it with compost but mostly aged manure to make some good soil but it is SLIGHTLY more clay than loam. Fertilized once with dumb ol' Miracle Gro about 4 years ago . Based on that here is what I do and it works for heliconia, gingers, guava, canna, plumeria, sugar cane (well, this takes more water really), N.Z. flax, BOP, spider lily, poinsettia, passionfruit, macadamia, brugmansia, stephanotis, agaves, aloes, and other stuff I can't remember.

Water well at beginning of hot summer. Let it soak until the water has saturated a few inches of soil well. That takes longer in So. Cal. if soil like mine. Nothing I have ever read, heard or seen would support this method, but on the flip side, I sell plants to landscapers, and flowers to the florist industry. They are oversized and more prolific than any I have seen and incredibly vigorous and healthy.

This is the weird part: I don't water the soil again until late summer (3 mos). The only water these plants get is twice weekly (but sometimes I only get it once except when hottest). I put the hose nozzle on a strong mist setting and wash the foliage on the whole stand of ginger (or whatever plant) for about 3-5 minutes total. This will wash off the leaves, trickle down to the soil and provide what So. Cal is lacking - humidity.

Do you want to trade for some already tall gingers? I'd be happy to set you up with some 6 or 7 footers.

Lisa
lthreeisme@yahoo.com

Lisa,
Your garden sounds wonderful.Thanks for the trade offer, but I am patient. I am new to tropicals. I have several gingers, cannas, caladiums, as well as an ice cream banana planted in the same border with the zerumbet in back against the fence. Everything is much taller than the zerumbet, the zerumbet was planted 4-6 weeks earlier, that is why i thought i might be doing something wrong. I have been having excellent luck using this border as a plant nursery for growing things from 4" pots until they are big enough to be put in the ground. Can I prune the zerumbet, remove some lateral growth and bushiness, to keep it going vertical? Or will this make it flop over?