Sunday, 15 January 2017

Parthenocarpic zucchini days to maturity

I am growing an heirloom Nordic variety of zucchini (Cucurbita pepo) which I know very little about.  Unfortunately the information I was given was written in Swedish or something and I was unable to translate it, based on its binomial name I guessed it was a zucchini, I knew its name, but that was about all.  Considering that spaghetti squash is also C pepo, as are several patty pan squash, and several other types of squash, I was far from certain that it was even a type of zucchini.  It made it kind of fun to grow, not really knowing what to expect.
Gron Busk 'Veribo'
 Zucchini: Gron Busk 'Veribo'

I am growing this heirloom Nordic zucchini.  I assume that "Gron Busk" means zucchini or summer squash or something along those lines and the variety name is "Veribo", but I really don't know.

It grows pretty fast, much like any other heirloom zucchini.  It grows green fruit which look similar to many other common varieties of zucchini.  It lacks any real taste and cooks well, much like any other zucchini.  It is highly productive (being an heirloom probably yields slightly less than most hybrid varieties but one plant still yields plenty of fruit over the season), which is much like any heirloom zucchini.  So far in my garden it is yet to experience any disease or pest other than Rutherglen bugs (Nysius vinitor), so I am not sure if it is resistant to anything.

One thing I love about this variety is that it produced female flowers first.  All of my Gron Busk 'Veribo' plants produced female flowers first this year.  This is very rare, normally zucchini produce male flowers for a while, and then eventually get around to producing female flowers, which means that it often takes longer to produce a crop.

Producing female flowers where there are no male flowers often means that the fruit will not grow and the flower will simply abort.  Yes, you can the eat zucchini flowers, but I don't want to, I want larger fruit.
Zucchini days to maturity
Parthenocarpic zucchini

This variety appears to have another trait which I love, it is parthenocarpic!  That means it will flower and if the female flower is not pollinated it does not abort and drop.  Instead it will naturally grow into a seedless fruit.  This increases the yield and makes the first crop much faster.  It also means that if you only grow one plant and it happens not to have male and female flowers at the same time then you will still get a crop.  This is very handy for home growers with limited space, this trait should not be as rare as it is.  Someone should breed this trait into more varieties of squash.

I am not completely certain that this variety is entirely parthenocarpic, or if it only displays this under certain conditions.  Some plants are only parthenocarpic under certain conditions, I grow some tomatoes that are only parthenocarpic when stressed, and if not stressed still require pollination to form fruit.  I have bagged a few female zucchini flowers before they opened, and each of them grew into a large zucchini, so I am assuming that it is pretty happy to grow parthenocarpic fruit.

Being an heirloom Nordic variety means it has likely been grown by families under harsh conditions and short seasons for generations.  Perhaps it copes with the cold better, perhaps it crops faster, I don't know, but I have recorded my results below.

Zucchini (Cucurbita pepo) Gron Busk 'Veribo' Days to Maturity

Planted 16/10/2016                  day 0
Germinated 25/10/2016            day 9
Flowering 29/11/2016               day 43
First small fruit 03/12/2016        day 47
Large fruit ready 07/12/2016     day 51

What do Days to Maturity mean

Quite often I see seeds sold with 'days to maturity' or something similar on the packet.  Unfortunately that means absolutely nothing.  Depending on the company it may mean how many days from transplant until the first flower opens (male or female).  Others use days from transplant until the first flower bud is seen on the plant several weeks prior to it opening.  Others use days from transplant until the first harvest.  Others use days from transplant until the fruit is mature (we eat immature fruit from zucchini).  As you can see, days to maturity is poorly defined and rarely are you told what definition they are using, so it is meaningless.  Cucurbits tend to perform better if not transplanted, so days to maturity which is based on transplant date is all the more meaningless for home growers.

I planted the seeds directly in the garden and counted from there with the planting day being day zero.  In different climates or under different growing conditions this will vary, but it is the results of several plants in my garden this year.  Even so, 51 days from planting the seed until eating a large zucchini is pretty good.

For a full list of vegetable days to harvest please click here.

Where to buy parthenocarpic zucchini seeds in Australia

I have bagged a few zucchini flowers and hand pollinated to obtain pure seed of this variety.   If I have enough I plan to sell them through my for sale page.  Any number of things could go wrong before the seeds are ready, including the flower not being pollinating so the fruit is seedless, so I can not take orders before the seed is ready, but I should have them for sale sooner or later.


  1. Hi, really like your blog! being Swedish and Norwegian speaking I can confirm that it most likely is a swedish variety. Grön busk in native letters. Had it been from norway the spelling would have been Grønn busk instead. Straight translation: Green bush/bush-like. Pronounciation of the o with double dots is kind of like ir in bird or ear heard or o in word but usualy more open, think more australian than posh brittish. Often it is pronounced like å, an a with a ring hovering over it if your browser don't show such exotic characters, by english speakers. Like babybjörn. I hope you keep writing!

    1. Hi Pilsnerstock,

      thank you for helping to translate! Is there any chance you can translate the name of a pumpkin I have? It is "Kaempw Melon Rilon" and I think the a and the e were joined and may have had a dot over them? It was messy hand written so is difficult to tell for sure.

  2. Glad to be of help! You put out a lot of interesting stuff so it's the least I can do. In this case I would guess the origin is in either Norway or Denmark as they use the letter æ and in sweden and Finland the letter ä is used for about the same sound. Sounds like the a in bad with an American accent. Kæmpe means either big or great in Norwegian and Danish, in Swedish it Means fighter. So you are with scandinavian measures having a big melon. Rilon I have no clue what it means, maybe a place name?

    1. Thank you! It makes sense, it is a large pumpkin, it is also a survivor.

  3. Did some googling, seems to be only three people named Rilon in Denmark and only young ones at that. Kæmpe is the Danish spelling, kjempe Norwegian. Could be that Rilon is an old name taken back into fashion? Pure speculation from my part here about Rilon but pretty certain it is Danish atleast!