The end of the road is in sight for pumpkin growers come early fall. To end on a flourish, a few key tasks need doing in September to help your pumpkins finish ripening and give you the best crop this year.
Maintenance shifts in September into helping the fruits mature properly. That means adjusting your watering and fertilizing habits from the summer routine and taking important steps to give the fruits the best conditions to ripen. In colder climates, September is also a month to keep one eye on the weather forecasts, as they need lifting before frost.
If you have been growing pumpkins all summer, it won’t be long before you are harvesting the fruits of your labor. Here we look at what to do with pumpkin plants in September to ensure the fruits ripen and cure properly. A good set of pruning shears (like these strong steel Corona pruners at The Home Depot) will be handy for completing some of these tasks and cutting the pumpkins from the vine come harvest time.
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1. Reduce Watering
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When your pumpkins reach their full size and the color starts to turn as the fruit matures, the plants no longer need as much water as they did in summer. You may have gotten into a good habit of watering plants regularly during the hotter months, but you can dial back the routine come September.
When you see the color starting to change and the foliage drying back, don’t keep deep watering as often as you have been. You should keep a close eye and stop the soil from completely drying out (a soil moisture meter from Amazon can help), but the plants don’t want a regular soaking.
Cutting back on watering pumpkins at this stage helps the skin to toughen and improves the flavor. If you overwater, the skin can split, or the pumpkin won’t store as long if the skin hasn’t hardened fully. Finally, stop watering about 2-3 weeks before you expect to be picking your pumpkins off the vine.
2. Stop Feeding
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Pumpkins need a lot of feeding during the summer to develop those long vines and large fruits. Once we get into September, continuing to feed will encourage the plant to carry on growing. Instead, the impetus should be letting the fruits mature and start to cure on the vine.
The window to fertilize pumpkins ends four weeks before harvest time. If you have been diligently using a high-potassium liquid fertilizer every few weeks, you’ll have given plants all the nutrients they need to be successful. But now leave the bottle of feed in the shed and don’t give the plants any more.
Continuing to fertilize into fall stops the fruits from developing the tough skin that is essential if you want to store pumpkins for long. Stopping feeding lets the fruits mature and cure naturally.
3. Boost Sunlight
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Direct sunlight plays a pivotal role in helping the pumpkins ripen on the vine. Now is the time to maximize that potential and give your fruits a helping hand by moving or removing any of the large leaves casting shade over the ripening pumpkins.
Look over your plants for any foliage blocking sunlight from reaching the top or the sides of the pumpkins. Remove them with sharp pruning shears (or garden scissors, like these on Walmart) to increase how much direct sunlight reaches the fruits, which will help speed up ripening.
To help plants remain healthy, gardeners can also remove dying, damaged, or diseased leaves (powdery mildew is a common issue in late summer and early fall). However, don’t get too carried away and remove lots of healthy leaves. The pumpkin plant still needs a good stock of these to photosynthesize and ripen the fruits.
4. Trim Long Stems
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To truly focus the plant’s energy on ripening the existing fruits, keen growers can also prune the pumpkin vines this month. While not essential for pumpkins in September, if you are against the clock to make sure the fruits ripen before the temperatures drop, it could make a difference.
By cutting back the pumpkin stems, the plant’s energy is diverted away from growing the vines and focused on ripening the fruits. Helping the fruits get a little extra dose of essential nutrients can reap rewards as we approach the business end of the season.
If you want to try this, cut the vines off around three feet past the ripening pumpkin. Any shoots that aren’t carrying fruit are also surplus and can be trimmed off to ensure they are not robbing nutrients from your pumpkins.
5. Lift Pumpkins
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A quick two-minute job for pumpkins in September is to lift the fruits off the soil, if you haven’t already.
Pumpkins sitting on damp soil – which is very common in September – can rot. Don’t let this happen to yours by placing a piece of slate, tile, brick, or wood under the fruits to raise them off the ground. This reduces the risk of the base of your fruits rotting before you pick them, which would be a devastating find come harvest time.
This also raises the fruit away from slugs, which are known to nibble developing pumpkins, but they shouldn’t do any serious damage once the skin has hardened.
6. Check for Frosts
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When gardeners need to pick their pumpkins varies by US hardiness zone. In milder climates, gardeners can leave the fruits to ripen on the vine through September without worry.
In colder climates, like US hardiness zones six and below, the pumpkins may need to be harvested if a hard frost is on the cards. Check forecasts if you grow in zones 3-6 and harvest pumpkins before a predicted hard frost. The fruits can survive a light frost but will be damaged by a hard frost, so pick them if they are mature or almost mature.
In September, if your pumpkins show all the signs of being fully ripe (including a full color, a hard rind, and a dry stem), you can harvest them.
Leave a few inches of stem attached when you pick them and cure the pumpkins for a few weeks somewhere dry and warm. This can be outdoors or in a greenhouse, sunroom, or on a sunny windowsill if you have cold or frosty nights.
Many pumpkins do end up getting discarded after Halloween. Personally, I grow pumpkins to eat rather than for display, but if you use yours for decorations, there are ways to utilize them around the garden after the seasonal celebration.
You can compost pumpkins to make nutrient-rich organic matter for plants to benefit from in future years, or you can use leftover pumpkins as fertilizer by breaking them up and burying them in the soil. However, if you do the latter, you may want to remove any seeds to avoid rogue pumpkins popping up around the garden.
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