Fertilizer is one of the most important elements of growing a good crop of ginger. More often than not under fertilization is the cause of weak ginger growth and rhizome formation. Yes you can have too much fertilizer but most ginger farmers would have a hard time affording that much fertilizer! Get a soil test!
If you are looking for a magic formula that works for ginger everywhere, I am sorry but there is none. Every situation is different and the amount of factors involved achieving PERFECT FERTILIZATION is mind boggling. That being said it is not hard with a good soil test and some practice with the crop to achieve fantastic results.
Chicken Manure is an excellent all purpose fertilizer as longs as it is good quality. We use a pelleted heat treated product. If you to were use 1 type of fertilizer only chicken manure would be it in most cases. Please be aware we use a relatively high nitrogen 4-3-2 material.
Generally for pre plant we would use a high phosphorus (P) fertilizer while for active growth would switch to a high nitrogen (N) fertilizer, before finally switching to a higher potassium (K) fertilizer to finish crop.
Compost is a good addition to fertility program if it is of high quality and contains no pathogens. Be careful where you source your compost from. Also Compost usually does not contain enough fertility to support proper ginger growth without additional fertilizers. Compost may contain enough fertility to grow leafy greens and lettuce but not ginger or turmeric. That being said compost will definitely improve your soil structure so a good quality, clean compost is recommended.
How much fertilizer do I use?
Good question. First start with a soil test. I would say to use as least as much as you would for tomatoes but allot of folks under fertilize their tomatoes too! Every soil or media is different.
Here in Hawaii it is common for a farmer to use 1-2 or more pounds of chicken manure per row foot pre plant. One must be careful to not over apply phosphorous (P) in production soils as it can accumulate more readily than the other elements. Too much P and you will be working against yourself. When in a element is overabundant in the soil cation it basically pushes out the other elements and thus you will need to use more of the the other elements than you would without the excess.
One must also take into account rainfall, soil types ect...
When most of the growing ginger reaches 8-12" in height it is probably time to start adding more fertilizer. High nitrogen (N) content of fertilizer would support foliage growth during the plants vegetative stage. It is important that the plant has access to all nutrients it needs THROUGHOUT the growth cycle even if we are adding extra during different stages of plant development.
Special notes for container culture
Firstly what media will you grow in? We recommend coir (ground coconut husk) as it really does grow nice ginger. It takes to water easily and does not harden in the event it dries out. Coir can be used as a stand alone if you are able to control your irrigation properly or with an aerating aggregate like perlite if you like to over water... Coir also is a renewable resource! That's right no need to dig big pits in the ground and release tons of greenhouse gases to extract it. One area of concern for growers is the risk of high salt content in inferior coir. You should use material from a quality source or otherwise rinse it by over watering it and allowing the salts to leach out, however this usually is not necessary.
Peat media is readily available although we find it can be mucky and be very hard to re hydrate should it inadvertently dry out. If you choose a peat product make sure that it has a good proportion of perlite or other aerating aggregate incorporated into it.
Both coir and peat in their natural form are essentially blank slate as far as nutrient content and thus must be amended with all the magical things that make plants grow. Perfection while to be desired is rarely achieved...