Keukenhof

I am worried that the first week of April is too early.

No, I don't think so.

Occasionally there are very cold years and some of the bulbs come up late, but my bulbs are already starting up here in England and I don't think that the Netherlands has had a harsh winter this year.

The garden will have been open a week or 10 days before you arrive (23 March) and will be a great show. Don't forget the displays and shows in the permanent Pavilions.

how easy is getting to/from Keukenhof using public transportation?

Very very easy by special bus from the airport, Amsterdam and Leiden stations

Their website https://keukenhof.nl/en/ gives information on getting there. The easiest is from Schiphol airport; the best, of course, via Leiden.
The first week of April is early season. Their Facebook page might give you some clue whether it's worth visiting or not. If not, there is always Haarlem as a good day trip. Or Leiden.

Keukenhof opens March 23, so I wouldn't say the first week of April is too early at all. They specialize in early-blooming bulbs. Their website (keukenhof.nl) has directions on how to get there by public transportation. I think you'll kick yourself later if you miss it.

The bulbs are replaced or layered to produce a decent show for the entire term of their opening. That said, they also have annuals and perennials, which will not be at their peak in the first two weeks. No one can predict climate that far in advance, but the views of the adjacent commercial bulb fields (that is, from Keukenhof, no additional travel required unless you want to see more) is unpredictable. If you're lucky, the crowds might be better in the the first two weeks. This attraction is VERY popular. Avoid the weekend if you can.

Edit: Anyone interested in Keukenhof might consider the weekday flower auction at Aalsmeer.

Go on the 4th so the garden has little more time to bloom it is still kind of early I was there last year March 26th a little too early But the flower galleriey is cool to see

Check out this site, and you can register for a weekly update on the progress of the bulbs. http://tulipsinholland.com/

Does anyone know if the combination ticket sold on Keukenhof's website (https://keukenhof.nl/en/plan-your-visit/how-to-get-there/) that includes a bus tranfser from Schipol Airport as well as entrance to the gardens provides round trip bus fare? I will be going to the gardens from Schipol and will want to return to Schipol once I am done visiting the gardens and I'm just trying to figure out which part of the bus fare the ticket covers. Thanks!

I bought the combination ticket from Keukenhof web site last year and it included the bus transportation from Schipol airport to the garden and back and the entrance ticket. There are people will check your ticket at the airport bus stop, as well as at the entrance of the garden. If you travel on the weekend be prepared for long line for the bus. Enjoy.

Thanks! I just ordered it and there were more clear instructions on the ticket itself that was sent to me that clarified that it was round trip, but I just wanted to be sure.

We took a tour of the Netherlands and Belgium in 2014. We went to Keukenhof on April 4. The flowers were magnificent! I agree with Tim's suggestion of Aalsmeer auction. You could potentially visit there in the mornin (early!) and go the Keukenhof late morning for the remainder of the day. Enjoy!

I will just point out that the Aalsmeer flower auction is rapidly declining as most trade is moving to online platforms. It now has probably half the buzz it had 5 or 6 years ago.