Well, this is a difficult one to cover. HOWEVER, the reference I will be using is extraordinarily thorough and covers most of the other topics for Ginger Lilies.
The first reference covers How to Grow, Pests and Diseases, Propagation, Uses, and a list of some species. Toward this end, I would like to make some comments that are, to me, of particular importance in growing ginger lilies.
Hedychium - A Hardy Ginger Plant for the Garden
A primary source with my comments.
One thing that you might want to take advantage of is the sweet smell of the flowers. Ginger lilies can be grown in large containers. Make sure there is plenty of room as the rhizomes can multiply to the extent they can break a pot. Be aware that they need a lot of water and if they are grown in a pot you may have to water once a day! Also, depending on the variety and where you have them and how you are taking care of them they can grow to 10 feet in height. Most of mine in the yard are about 5-8 feet in height. They do prefer sun or part shade and here in our area due to the heat. Do remember that more sun translates to more flowers. I do have a number of gingers in shade and they seem to do okay. During dry spells or the occasional drought, they must be watered fairly frequently. When you plant them outside in our area check your soil and make sure it has plenty of organic material to retain moisture. A lot of the gardens and yards in our area are quite sandy so be sure to add compost or other organic material. The soil should have a slightly acidic pH. A sprinkling of 10-10-10 once every week or two helps as they are heavy feeders. You can also use bone meal or other organic fertilizers.
They may last through the winter IF we have a very mild winter. I have found that if there are under tall trees, pines, this helps them from die back in the winter. However, I generally expect them to die back. You can let the stalks die back, fall to the ground and this will be your ‘mulching cover’ for the winter. I generally trim my stalks by cutting them to about 2-3” and use pine straw to provide protection from the cold day – looks neater. You can also dig up the rhizomes and save them in peat moss or sawdust for the winter.
I have never had problems with pests as gingers are fairly ‘pest proof’. Just keep watch to see if any pests do attack the plant. BTW – I have not had deer problems with gingers and we do have deer in our neighborhood.
When the flower on a stalk finishes blooming cut the stalk off at the ground – one stalk is one flower! However, if you want to collect the seeds to let the flower stay until you can collect the small red or black seeds.
When do they start growth
In the spring there is no telling when they will send out new growth! Some of mine sent out new shoots from the rhizomes in early March - be careful of a frost though as it will nip them. It is now the latter part of April and the early growers are doing well and up almost 3 feet. Others like the Pine Cone Ginger have just started coming up. I still have some that I do not expect they to start coming up from the rhizome for another month. Point is that it depends, primarily, on the variety and the amount of sun they receive.
Gardening in the Coastal Southeast
This article specifically addresses the care and cultivation of some gingers that grow in our area. Specifically in USDA zones 8 and 9.
The main takeaway with this article is pointing out that gingers can grow in USDA zones 7-11! It emphasizes that ginger lilies are NOT drought-tolerant and must be frequently watered. This may mean every other day in hot dry conditions. In my case I am not that ‘caring’ and they do fine. I will put a sprinkler on them at least once a week. The University of Oklahoma recommends a weekly feeding with a balanced fertilizer, i.e. 10-10-10.
All about growing Hedychiums (Ginger Lilies)
The article specifically addresses when to plant the rhizomes. DO realize this article is from the UK which has zones equivalent to our USDA zones 6-9. But has applicable comments we can use here. They do describe several really nice gingers which you may be able to find in the states.
One MUST remember that there are two main issues to consider when growing ginger lilies! This is that they are heavy feeders and drinkers. Recommend a 10-10-10 or even better a 10-20-20 fertilizer. Too much nitrogen and you will have great leaves at the expense of flowering. Do not add the fertilizer immediately on the rhizomes as they can be burned but fertilizer 6” to a foot from the plants. When they start flowering go to a potassium-based fertilizer. Use a fertilizer with trace elements. You will want to fertilize them every few weeks.
The other main issue is to be sure they have enough water as they do like moist, but not wet, soil. Too much water and the rhizomes will get diseased and you will wash out the fertilizer.
Ginger Lilies have insect problems as do, virtually, all other plants. I have found this is not a major issue but certainly something to keep in your mind as you raise your gingers. I would suggest that you clean up old much each year and mulch with something like pine straw. Be observant of your plants and if you are not sure what pest is infesting your plants take a sample to your county agent or local nursery. They can tell you what the pest is and recommend an appropriate insecticide.
While tropical gingers are easy to grow from rhizomes, persuading the plants to flower may be difficult in the average garden.