kabocha; how long does it take to mature?

March 4, 2010

I need advice from somebody who has experience growing kabocha. Kabocha is a Japanese variety of pumpkin.

I ordered a packet of it from a seed company that specializes in Asian vegetables called Kitazawa seed.

The only thing it said in the catalog in regards to how long it takes to mature is "45 days from flowering".

This to me is really vague, because I know that with squash and growing them, all of them flower and when they flower they're close to maturing.

I tried to call the seed company to get clarification regarding this but even they didn't know. Does anybody know what the full maturing time is for kabocha from growing to seed, until it's ready to be harvested?

Also how well does it transplant? What type of soil does it like? Is it a heavy feeder in regards to fertilizing?

Comments (9)

  • farmerdilla

    There are quite a few varieties of kabocha/buttercup type squash. All are C. maxima. While there is is variance (90 -130 days) all of them take 3-4 months from seed. Comparable to Halloween type pumpkins, Hubbards, Buttercups, etc. Kitazawa sells the hybrid Sweet Mama, one of the more popular hybrids, which is early at 90 days.

  • carol_in_california

    I grew some last year and it took several months before they were full sized and ready to harvest.
    I had a wonderful crop and plan on growing some more this year.
    The ones I planted were from the seeds of a kabocha squash I bought at the market.

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  • cyrus_gardner

    probably, the seed description is correct when it say
    "45 days from flowering"
    This means they are talking about the squash itself, not the vine.
    So from the time the fruit starts to the time it matures
    takes 45 days. This sounds logical, since the plant age does not
    matter much, but the fruit itself.

  • Brenda K Spevak

    Hi there KawaiiNeko-san,

    I grew some mini kabochas last summer from seed I brought back from Japan five years ago, but with mixed results. I still havent quite figured this all out, but IÂm happy to share what I learned from that experiment that went haywire.

    First of all, my seeds (the variety was called "Botchan") were still viable even after five years of less-than-ideal storage conditions! Anyway, I planted two seeds in a ridiculously tiny space between our veranda wall and the retaining wall, crammed behind three little 5-gallon citrus trees I had put in there a few months earlier in April 2009. I fed and watered everyone well and waited to see what would happen next. If my memory serves me, I am pretty sure I put the Kabocha seeds in either late May or early June 2009.

    Well, after taking a little while to get going (a month or so since we had an unusually long, chilly spring and it didnÂt really get into summer weather until the 4th of July), they took off like rockets and grew like crazy, sending out lateral shoots off the main vines every which way, completely buried and strangled my poor little citrus trees with their long and numerous tendrils, and made their way rapidly up the rickety trellis I built and installed (belatedly) against the veranda wall behind them and proceeded to set loads of fruit after a spectacular flowering period. I think this was around mid to late July.

    Like most summer annuals, pumpkins are very hungry and thirsty plants, as are citrus trees, so I made sure to keep them well fed and watered. Thankfully (and unbeknownst to me at that time), the type of food I was using seemed to agree with both types of plants in that location, i.e., organic Citrus and Vine Food (I canÂt remember the maker right offhand). That was apparently so successful that I was left with no choice but to have to do a "Mack the Knife" operation on the kabochas, or run the risk of heavy casualties on my citrus trees. That was good for many hours of back-breaking hard labor (Man, those vines are heavy!!) on at least two occasions (they grew right back and buried the citrust trees again within a couple weeks of cutting them back!!) which I am sure harmed the plants so they did not produce as much if they would have if I hadnÂt had to prune them back so brutally just as they were fruiting.

    As for your questions about soil type, I have massively heavy, sticky clay soil that I dug deeply and added some sand and compost and KelloggÂs "Amend" to lighten it up, and also here in southern California we tend to have alkaline soil due to our hard water. Those conditions apparently didnÂt deter the pumpkins one bit because they grew like crazy.

    I was surprised by how quickly the pumpkins matured, i.e., turned from beautiful little pale green variegated marbles with huge golden flowers at the ends into cheery little fist-sized mini kabochas just like the ones I find in the Japanese supermarket. That transformation only took a few weeks (i.e., from mid July-ish to late August-ish). Now this is where it gets a little fuzzy. Apparently kabocha are quite forgiving about timing of picking them. They are apparently done enough when their color looks right, i.e., dark green, but they can be left on the vine until the leaves start to die off in the fall. Ideal picking time is said by some credible sources to be when the stems looks "well corked" (I think that means kind of dried out and shrunk like a melon stem when the melon is ready). Also, my research indicates that youÂre supposed to "cure" them by letting them sit for a few weeks after picking so theyÂll dry out, which apparently heightens the sweetness and flavor. It looks like it was a solid four months between planting the seeds and beginning harvesting the fruit, and then add 3 more weeks or so of curing time.

    I havenÂt by any means perfected the timing of harvesting and curing since IÂve only had one pass through this process so far, so that is apparently why a few of mine turned out delicious and sweet, while others were not. I picked the first one too early, didnÂt cure it but just cut it open and roasted it on the grill right after picking, and it was tasteless and a little bitter.

    I canÂt speak from experience to your question about transplanting them since I direct-seeded mine, but given their extensive root systems and research I have done, they are not overly fond of being transplanted, but it looks like you have no choice given your location and its climate and the long growth cycle of these plants. However, since they are related to melons, perhaps this advice will work: an avid melon grower starts his plants in 5-gallon pots lined with chicken wire (with the chicken wire coming up far enough outside the pot so you can grab it) filled with sterile potting medium, and then when itÂs warm enough to plant them outside, the seedlings can be lifted out of the pots without the root ball getting all messed up, and the large pots have given the roots enough room to spread out. Here is the link to that fascinating site, but note that you have to look at it with the internet Explorer web browser, as when I tried it in Firefox, it just came up as HTML code: http://www.waynesthisandthat.com/melons.

    Well, this year since IÂve come a long way in the learning curve and have a plan for much better vine management, IÂm going to try my "Ebisu" full-sized kabochas! Stay tuned for the progress.

    Best of luck with your kabochas!

    Brenda K in L.A.

  • Jack wo

    I am newbie and do not konw how to grow vegetable, I ate kabacha from local store at April, I think that it was grow at Mecico. It had many seeds, I put seeds in soil and it grew to big plant at June with many flowerd, However, all bady kabacha dropped due to missing bee, bees came at June and now, It has many Kabacha, I live at cool summer area PNW and not good for gardening.

    Kabacha grow fast, and I think that it ripen 30 days to 60 days depend on soil/fertilizer, much shorter than I think.

    It had 10+ kabacha and then it dropped new baby kabacha, I feed them wrong fertilizer like 10 10 10, I feed them with low nitrogen fertilizer, like 2 15 15, it grows more kabach now without dropping.

    It is great plant for cool summer area but it needs lots of fertilizer and water everyday.

    Next year, If I grow it again, I will sure hand pollinate them so It bear kabacha one month ahead.

  • Joyce Chapman

    I am new with this as well. I love Kabocha squash and I had saved some seeds from one I bought at the health food store a few years ago. I was late in planting, probably late July and it took them about a month to really get going. The male flowers came first followed by the females about 3 weeks later. It is now August 2 and we just hand pollinated our first female flower this morning. I am so excited! We don't have many pollinators in this area and I had read before that if you want to ensure you get fruit you should probably hand pollinate, so, that is what we did. I planted only two squash this year. We have about 10 more female flowers that are not mature enough to open yet. I check them every day because the flowers are only open for a very short time, so, the window of opportunity is very small. I can't wait to watch the babies grow. I am hoping I can get about 10 squash off of the two plants. I have read you are lucky if you get one per vine, but, with hand pollinating I am hoping for at least two. I now have 5 vines growing. They are very aggressive and seem to take over whatever is in their path. I have a second year carrot growing for the seeds and the squash seems to be taking it down, literally. I also have spearmint growing to the side and so far I have been able to detour the squash by simply picking up the vine and moving it away from the spearmint. If you move them as they are first growing outward they seem easily deterred. I didn't have to move them much, maybe only 5 inches. I love these plants and have gotten a lot of joy out of watching. I water them every night when the sun goes down. I planted them in a manure enriched soil I bought at Walmart. I have not used any other fertilizer on them and they are growing great. However, I did read that the key to growing these squash is Patience, patience, patience. They are not something that grows overnight. Also, don't be too anxious to harvest them. They are suppose to stay on the vine until the vine dries up and falls away from the fruit. In the end they stem looks like that of a pumpkin. I hope you are enjoying your plants as much as I am mine. I am planning to plant a lot more next year and in a place in the yard where they have lots of room to branch out without worrying about them taking over any other plants. Good luck to you. :)

  • Patricia Stevenson

    I threw out my parrots food and one grew. And it just happen to be a kabocha squash. I just wanted to know when to harvest them. We got 4 Sqaush on this one plant.We did pick one and cooked it it was wonderful and tasty but think it could of went longer. I have 3 more on the vine yet. It's been two weeks since we picked that first one. But I want to make sure I don't pick the rest till they are done. We plan on planting 5 or 6 plants next year. We will save seeds to plant And the rest of the seeds feed it to our parrots.

  • Jack wo

    I would like to report this, I grew kabocha squash this spring, It sprouted very early at April even as low as 55F/12C, it grew fast even at 63F/17C end of May and it had many flowers at end of May and dropped without bee, Bee appeared at Mid of June, Kabocha squashes took 3 to 6 weeks to mature, you scratch its skin, If it is soft, it is not ready, When it is rough with hard skin, it is ready.

    However, you should not eat its squashes rightaway, They need to store for a month+ to become sweet and more tasty.

    Just like some people like oranges and some people like apples, Kabocha squash is not for everyone, basically, If person likes sweet potatoes, They should love it as well, Its taste like between sweet potatoes and sweet chestnuts to me.

    I grew Cheyeche squash as well, They bears so many squashes, in order to maintain high production of squash, you need to prepare soils before you plant it, I heard that people grew them on 18 inches wide rich compost manure soil hill with good results, I will try it next year.

  • jensyen ( z7 MD )

    Jack wo, I googled 'Cheyeche squash' and didn't find anything. What is this prolific squash?

    I am growing kabocha squash this year and can't remember when it was planted or flowered. I only had 2 fruit that I can see growing in all the vines. Next year I will try using better soil and fertilizer and do hand pollinating like Joyce mentioned. I got my seeds from a small squash and was surprised to see them grow much larger fruit. It is early October and they look mature on the vine. I will scratch them to see if they are hard like mentioned above. I'd like to share the seeds so I may let them remain on the vine until threat of first frost.

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