You might give it a little flowering fertilizer... if you give it too much N, you will get a big vine and small fruit.

Thanks! I found some organic slow release fruit and flower fert 4-6-4, good for 10 weeks. Pumpkin is getting bigger and darker green.
How do I know when it's ready to harvest?

I can't read Japanese... but I would guess-- (according to this link),
the pumkins will be ready in 40 days (after blossom) when the skin is getting hard.
Does anyone speak Japanese? Please help :)

Here is a link that might be useful: URUZO

Hi - general rule of thumb for winter squash readiness is to check for hardness w/ your fingernail - when you cannot pierce the skin w/your nail, it's ready.

I just wait 'til vines die back.

Yum - I love kabocha!

Thanks for the tips! I think it's 40 days right now. Carolb, does that mean the plant only produces 1 pumpkin, then will die? I don't see any more blossoms.
Also one of my plants produced a kabocha but did not vine. So the kabocha is growing at the plant base. Will it be ok resting on the ground (that's covered w/ burlap)?
What happens if you leave it on the vine too long?

How easy (or difficult) is it to grow kabocha on the southern California coast, within 1/2 mile of the ocean? I have never tried pumpkin of any kind in my garden, but am wild about kabocha.

Arlene, I am a long way from your location and hope that you get a response from someone local. I can say a little about how difficult/easy it was for me growing kabocha.

My problem seemed to be that the varieties I was trying seemed unable to properly mature here where night-time temperatures are cool through a fairly short growing season. Burgess buttercup squash, which is related to kabocha, has always done fairly well for me. It think it was just a matter of finding varieties that matured more quickly than some of the others.

I seemed to hit a double jackpot in 2010! This season started off very cool - too cool, and I lost any squash that I set out early to a late frost. So, I replanted.

Both Cha Cha Kabocha, and Kuribo did well enough for me to consider them successful. The Kuribo seemed to have a rather large seed cavity for such a small squash but I'll definitely grow the Cha Cha again!

Seed for Cha Cha came from Johnny's and Kuribo came from Kitazawa Seed. Kitazawa has quite a few kabocha varieties and they are in Oakland. They may be able to suggest a variety for your location.

On a totally unrelated subject, I was thinking how "old fashioned" this thread looked with the capital letters for Honu and ChicoGirl, etc. My GW name used to have a capital "D" back in 2005. They were all changed to lower-case about that time. . .

Then I see the upper-case "A" in your name!! I don't know when you registered but I just looked at a long list of GW names -- not one had a capital letter in them! Looks like GW has made a recent change.

DigitSteve

I got the seeds out of a Kabocha squash I bought in an Asian supermarket. I picked out the biggest prettiest looking one they had for sale. The seeds grew and last year I got about a dozen squashes, about one or two per a vine. After you pick them you have to let them ripen for several weeks to make the flesh sweeten. They will keep for a long time.
BTW, I am located in Orange County about 20 miles from the ocean, so yes, Kabocha will grow in southern California.
The vines will even try to grow over chain link fences into your neighbors yard.

Arlene, there is a chain of Japanese supermarkets called Nijiya Market, there are quite a few in SoCal. Their big farm is somewhere east of San Diego, if I remember correctly. So they are growing their own organic kabocha on a commercial scale there. Mexico is also a big exporter of kabocha to Japan.

Nijiya Farms also grows great Japanese Sweet Potatoes. You might go by their store and pick up a kabocha for seeds and sweet potato for sprouting. They also will have some asian vegetable seeds in stock.