coming out of winter rest.
 

So, when those dens are coming out of the winter rest, what's the best signal to restart fertilising?

1. New shoots?
2. Flower buds starting?
3. Either?

Edit June 15 2020:
Yamamoto Dendrobiums in Japan hybridizes and produces a great number of these plants. Their Web site formerly had excellent growing information for hobbyists. Unfortunately it is no longer there. You can still look at the varieties they grow, and maybe see one very similar to yours.

I saved the page, and summarized it in a post in this thread:
Uncertain if Dendrobium is still alive

Yamamoto now has a page showing how to force Dendrobium nobile for Christmas flowering in Japan's climate. There is a lot to learn from that page, but it is intended for growers who can artificially heat and cool their greenhouses during off seasons. Note they use coconut husk for growing medium, which many orchidists would say retains too much water for orchids. For many orchids that is correct, but this is a very thirsty orchid.

Nowhere in there can I find where it says when to start fertiliser up again.
Simple question really, which is best? start when the flower buds start to appear or wait till the first shoot, or doesn't it matter?

Bil, the answer is in ES's link:

1st case - For small plants grown without supplemental heat and where night temperatures fall below 46 F (8 C) in winter, apply fertilizer high in nitrogen when night temperatures rise to about 50 F (10 C), probably in March or April.

2nd case - If night temperatures in winter are higher than 50 F (10 C), then fertilize from January.

Basically, 1st case is when new growth begins. 2nd case when the blooms are finished.

I think I'm correct...unless I haven't understood your question.

Saying 'do it at this time or temp' is irrelevant for the amateur grower who isn't doing it wholesale for the market.
I have some dens with just new shoots, some with flower buds and new shoots, and some with just flower buds starting out..

I was just curious when the best time was for starting up on the fertiliser again.
Shoots, buds, or either?

I'm no help bil, but I see what you're asking. Mine is still going dormant, losing leaves. I'm going to error on the side of caution and not do anything until I must.

I see your problem. If they all have grown under the same conditions I would apply both cases depending of the plant. To those that have buds and growths, wel... I would start when the blooms die.

I would interpret that to apply high-nitrogen fertilizer after buds have formed, and before shoots begin. I would be surprised if it is true next season's buds are formed around or before the time shoots start emerging, but I haven't done the work with a microscope. So, I would definitely give high-nitrogen fertilizer when the shoots are emerging.

I have a Dendrobium Love Memory 'Fizz'. While reorganizing my grow space in mid December, I set it between a bench and the glass on the concrete floor, then forgot about it. It got some water because I throw a bucket of water on the floor each morning. I heat the space to a minimum of 60F / 15C. The plant probably had cooler nights, on the floor next to the glass. It is making a lot of either buds or keikiis; I can't tell yet which it will be. But after rereading those care instructions, I'm going to begin fertilizing once I know these are buds.

Yamamoto says they hybridize to make plants easier to bloom, and less temperature dependent. My plant's description is "easy grow and bloom."

Only problem with that would be no fertiliser for the next two or three months.
I think that in the absence of firm info here, I will stick to the adage of stopping feeding when growth stops, and the reverse, ie start when growth starts.
It seems logical that both flowers and shoots would benefit from nitrogen as soon as they start growing, but I am open to correction if anyone knows differently.

If I recall correctly, shoots like nitrogen but flowers less so. It makes sense to me, logically, that you'd fertilize when the shoots begin to grow. Of course, I don't grow this genus and so am taking a wild stab.