Hi fionasol,
When you bought it, were the leaves floating or up in the air? Its strange to see a blossom on there, with so few leaves. Very strange to me. Makes me think it received some steroids or something.
I'm no expert, but I'm thinking you have too many stones on top of it.
Is it possible that it got very cold after you bought it?
I know your area has had some upper 30's nights recently.
Very curious. Normally I'd say don't fertilize it until it has aerial leaves, but your's has a blossom.
I'm just not sure what to tell you. I hope some other lotus-growers chime in here.
Since it has a blossom, I would probably try a couple pond tabs. I just don't understand how it could put out a blossom with so few leaves.
What's the name of the lotus? Was it kept in a greenhouse when you bought it?

I agree , its too early for it to have flower buds . If it was in a greenhouse and you stuck it in your cold pond , it might have gone into shock . The gravel wont have anything to do with it. Just leave it alone and it should send out my leaves. Rick

The tag on the on the lotus said "Nelumbo White (Named)"

So, I know that the pond store had just gotten in the big delivery of plants earlier in the week that I bought the lotus, so it's a pretty good guess that this was a greenhouse plant. I visited the store again this week, and all the rest of the lotus they still from that delivery were pretty happy still in their original pots...but not in a pond...so they have been much warmer than my poor shivering guy.

Will just leave it be and hope for the best. Thanks for the advice.

Good luck fionasol.
All my lotus are VERY slow this year, so maybe yours will pick up soon.

Everything is being slow for me.

I have an American lotus that I got 2 years ago. It has been very slow from the start. It put up a floating leaf about 2 weeks ago, and when I was pulling string algae from the container, I accidentally pulled the leaf off! So now I'm waiting for leaf #2, My other 2 lotuses are extremely slow too.

I have a 135gal pond, The lotus bloomed well in the past 5 years. But my lotus did not come back this year, not a single leaf at all. The waterlily are fine and blooming now. I changed the new roof on 1/2009, and I found some roof materials had fallen into pond. I don't know it is the reason make the water quality changed and stop the lotus grow. If someone has the same experience, please let me know. Thanks

1tsao, is your lotus in a container? It probably needs thinning. I need to thin mine about every 2 years. Its not too late to thin, if you're careful.

Catherinet, The lotus are in the containers, I devided the roots last year, and the lotus were growing well last year. Should I take out the container now to check it still alive or wait for few more weeks?

Is there the possibility that when it was being transported (from grower to garden center, or from garden center to your house) that the stems might've been bent / broken a little?

I agree with all above, probably cold shock. You might raise it so the pot top is even with the water level so it gets more sun and warmth and when you see it doing better, lower it again. It's been too cool here in zone 5 for the lotus to do much. Mine are just sending up floating leaves.