Lifecycle of a giant pumpkin

How long does it take to grow a giant pumpkin?

It can take anywhere from 140 – 160 days to grow a giant pumpkin, and this can vary between sites due to climate, aspect, soil condition, seed genetics and a whole bunch of different factors. But planting in late October (Labour weekend here in NZ) will give you a pumpkin ready in March/April the following year.

To help work backwards to make sure you have enough time to grow for your event check out www.timeanddate.com, a great tool to help you work out dates in the future or in the past.

While it may take over 4 months to get a giant pumpkin, the actual pumpkin itself grows in a much shorter time frame, sometimes putting on as much as 20 + Kg’s a day at its peak. This is pretty mind-blowing when you think about it, one seed that only weighs a few grams can grow and produce a fruit that is in the hundreds of kilos.

Here is a rough timeline of what happens during a growing season.

By using this as a guide you can work backwards from your competition date to work out the best time to plant your giant pumpkin seeds.

DayEvent
1Plant seeds indoors
5Plant some extra seeds just in case
9-10Seeds should be appearing from the soil
20First leaves start appearing
22-25Transplant to garden
25-36Covering of plants to protect from cold nights might be needed
51Bugs that want to eat the plants start appearing
70Time to pollinate
73Pollination should be successful
75Time to switch to higher phosphate fertiliser
80Think about shade to cover your giant pumpkin
81Water, lots of water and fertiliser
82Fungicides may need to be applied
96Pumpkin should be around the 50kg mark if all is going well
100Skin starts getting harder, and ribs start forming in the fruit
111Skin will start to darken
126Growth starts slowing down
156Pumpkin is mature
160Time to work out how to move it