Punkin disorderly

Kara asked:

Oh wise garden one….my pumpkin plants have gone crazy but I’ve only just started seeing flowers in amongst the chaos, should I be seeing fruit (I haven’t really looked too hard….) and if not should I start doing pumpkin style rumpy-pumpy? And how do I know when they reach full size?

And can you please explain more about ‘pinching out the tips’ with regards tomatoes and pumpkins? I’ve seen this referred too but I really don’t know what it means….

Thanks!

Okay, first of all, Pumpkins (Cucurbita spp.), like the majority of their family the Cucurbitaceae, have separate male and female flowers. You can tell them apart because the females, as we would expect, have the ovaries, which develop into the fruit, in this case, the Pumpkin itself.

Female pumpkin flower, note the ovary at the base of the flower

Male flowers do not have the ovary, which looks like a miniature version of the full grown fruit in most cases. They simply provide the pollen, which you will see as little yellow grains, to fertilise the female flower, then they tend to drop off all together. That may sound familiar, but I will not expand the analogy further in this time slot.

Male pumpkin flower. No mini punkins attached

Without fertilisation, the female flowers will also drop off without developing into proper pumpkins. This is because the fruit itself is merely a vessel for carrying seeds of the next generation of plants. Without pollination to create fertile seeds, it is a waste of energy for the plant to grow a whole fruit with nothing in it. To help them along, it may be necessary to hand pollinate, especially if you don’t see any insects, such as bees, visiting the flowers. Most plants will produce more male flowers than female, and the easiest way to pollinate is to pick one of the male flowers and completely remove the petals (known as the corolla) until you are left with a stamen on a stem.

Male flower with corolla removed, shoddy camerawork model's own

Then you have to rub the pollen from this onto the receptive part of the female flower, the stigma, basically by just sticking it in there and jiggling it about a bit. You will notice the female parts  look different to those of the male. Shhh. That’s enough tittering from the back of the room, thanks.

Apply the pollen directly to the stigma of the female flower

And that is pretty much all there is to it. The female flower will drop off, and the ovary will develop into a pumpkin. As far as knowing when they are ripe, the best thing to do is leave them until the plant begins to die off, which will result in a tough, thick skin, allowing for longer storage of the pumpkins into the winter. Other Cucurbits like Zucchini and Cucumber should be harvested whenever they look edible. They are not so tasty when mature.

As for “pinching out” of plants, this is usually done to encourage branching and flowering, it really just means removing the tip of the growing plant. It doesn’t really matter how much of it you remove, as long as the growing point itself is severed, it will have the same effect of making the plant bushier and more compact. Lets say you can remove about 10cm from the tips of Pumpkin plants and about 5cm for Tomatoes.