It’s Time For Pumpkins! Also, growing your own pumpkins is really good fun. Watching the vines grow, flowers blossom and tiny little pumpkins form is really exciting. They require between 6 to 8 hours of sun light a day, rich soil improved with compost and lots of space or something to climb on. They are extremely easy to grow and can erupted out of your compost, without any help from you. The variety, well who knows, it depends on what you bought at the supermarket and what seeds went into the compost heap. They do have some quirky traits and it can be very frustrating when the vine is extremely healthy and you only get male flowers. It can also be extremely devastating if you think you are going to get a pumpkin to find it has dropped off. Pumpkins are notorious for not producing fruit.
Pumpkins belong to the genus Cucurbita and the family Cucurbitaceae which includes zucchini, water melon, rock melon, squash, cucumbers and gourds. The word pumpkin originates from the word ‘pepon’ which is Greek for ‘large melon’ It is classified as a vine and need lots of room to grow. Pumpkins are monoecious which means having both male and female flowers on the same plant, so you only need one plant to produce fruit.
Preparing the soil
Pumpkins like a soil pH between 6 to 7.2. If your soil is on the acidic side then we suggest you add some gardeners lime and if it is on the high side – alkaline – then you can lower it by applying sulphur. To prepare the soil for pumpkins, you incorporate lots of compost and cow or sheep manure. A good handful of blood and bone plus potash will be beneficial. Pumpkins are an annual crop and need a rich organic soil, so that they can grow quickly and produce fruit before the winter cold sets in. The soil also needs to drain well and if your soil is clay, so you make a mound using a good quality loam. This will raise their roots up above the clay and bad drainage.
Siting your pumpkin
Pumpkins need a lot of room and can smoother other plants if left unchecked. Now if you have a small garden and don’t wish to be invaded by the trifid plants then we suggest growing them up next to a fence or shed or putting in some lattice and training the tendrils up that. The good point about tying them up is that it gets the fruit off the ground away from pests such as slugs and snails and diseases such as mildew. If space isn’t a problem, then just let them wander. You will find you have a floating sea of large pumpkin leaves enveloping your garden. If they get into any mischief, just prune them back, it won’t hurt them!
The best time to plant pumpkin seeds is in spring, when the soil and air temperature is warming up. If starting them off in the vegetable patch, the soil temperature needs to be at least 20°C for germination and the air temperature 22°C. You can start them off in pots in a hot house if you like, but the garden soil still needs to be over 20°C when you plant them out. They don’t like the cold or frost.
When you plant the seed directly into the garden, make a mound about 1/2 meter wide and plant 3-4 seeds about 4-5cm deep. Depending on the warmth of the soil they should sprout within about 7-10 days. When the baby seedlings have between 4-6 leaves, pinch out the weakest plants, leaving the strongest ones. If you don’t pinch out the weak ones, the mound will be over crowded and none of the pumpkins will thrive. If you don’t want to disregard them, replant them somewhere else in the veggie patch.
Pumpkins are grown in summer, need between 70-120 days before they are ready to harvest and that is usually in early to mid fall. Pumpkins like don’t like scorching temperatures and will shut down and stop growing. They are shallow rooted, wilt easily and that is why it is important to prepare the soil with lots of compost and animal manure to help increase the water holding capacity of the soil. If the soil retains its water, then it is available to the plant to replace the moisture it is losing through its leaves. Pumpkins do not like being water stressed and don’t like the flood and famine watering regime. It can cause them to split. They like nice even watering and the best time is in the morning. If you water at night and the leaves become wet, powdery mildew can set in. Pumpkins don’t like wind and need to be protected from it. Heat and strong winds can cause woodiness which makes the pumpkin very unpleasant to eat. It is also thought that too much wind can cause scarring on the flesh.
The vine takes about 10 weeks before it starts producing flowers and the males are first. They are on long thin stems (called pedicels) and there are heaps more of them than females. If you peak inside the male flower you will find a long thin structure called the stamen which produces the pollen. The female flowers have a shorter pedicel and sit closer to the vine. If you peak inside the female flower you will see the stigma which is where the pollen is received. The ovary is at the base of the petals and is where the seeds develop.
Fertilizing the ovary
The flowers only open for 1 day; just before dawn, the flower petals start to unfurl and open for a 4 hour period. By mid-day they are beginning to slowly close and by dusk they have shut permanently. Pumpkins are pollinated by insects, especially native and honey bees, so it is important to encourage them into your garden. It is common for the female flowers ovary to swell and start to look like a pumpkin is forming. But disaster, it turns brown and drops off. This occurs because it hasn’t been fertilized due to lack of bees.
There are several things you can do to encourage them:
– Don’t use systemic (poisons that are absorbed into the plant and can last for several weeks) sprays, as many of them kill the bees when they eat the nectar of the flowers,
– Plant French lavender, it flowers nearly all year;
– Plant lots of Iceland poppies – honey bees adore them;
– Provide water for the bees, they will tell their friends and more bees will visit.
Now, if the weather has been beastly either too hot or too cold and you notice there are not many bees buzzing around, you can try fertilizing them yourself. There are 2 methods, hand pollinating using the male flower or using a brush. To hand pollinate, pick male flowers, remove petals then dab the pollen on the stigma of female flowers. You can try the brush method once, where you gently brush over the stamen, then gently brush it over the stigma but it didn’t work.
To save seed from harvested pumpkins, store it for a month, then scope out the flesh, wash it away and dry the seeds on paper towel. Then store them in a clean dry glass jar in a cool dry spot away from sunlight. It is also a good idea to label the bottle with the variety of pumpkin and date.
Pumpkins are notorious for cross pollinating with one another so to ensure true to type, save seed from one variety grown in isolation. You may need to hand pollinate it, to ensure there is no contamination of pollen.
Why isn’t my pumpkin producing fruit?
Pumpkins are notorious for not producing fruit and there are many reasons why.
– Pumpkins are weather and temperature sensitive. If it is too hot, too cold, too windy, too rainy then you may not get fruit. You try hand pollination especially if the temperatures are over 30°C. Remember, if the weather is eradicatic and temperatures fluctuate widely; then many plants shut down, until conditions become more suitable.
– It is thought that seed younger than 3 years old, produces more male flowers than female flowers.
– Lack of insects in your garden. Bees, ants and other insects are vital in the transfer of pollen process. If they aren’t present, then the pollen won’t be transferred to the female flower – thus no pumpkins.
– Heavy rain can damage the pollen, which means that even if it is transferred by insects, it won’t fertilize the flower and thus again no fruit.
– One trick to try to encourage more female flowers, is to nip off the apical (also known as terminal) bud (top point of growth) and encourage lateral (side) growth.
– Make sure when you prepare the bed that you incorporate some potash (encourages flowers) in and not put too much nitrogen in eg. blood and bone, which causes excess leaf growth.
Pests and diseases
There are the normal pests such as slugs and snails that attack the leaves. You can try picking them off by hand, especially after rain or use a snail trap of beer in a glass jar 1/2 sunken into the ground. They crawl in, get drunk and drown. There is also the finely crushed egg shells circle, that you put around each plant which they hate crawling over. There is a new product for pots, which is a copper strip that you attach around the pot. There is also a spray to repel them.
If you are having trouble with caterpillars, then we suggest using an organic spray called Dipel which the active ingredient is Bacillus thuringiensis. It won’t harm you, your children, pets or other beneficial insects. Longlife pyrethrum is also good for sap sucking insects such as white fly and aphids, but also kills caterpillars.
In regards to ladybirds there are the good one and the bad ones. The bad ones are known as the 28 spotted ones and they eat the leaves, so you need to watch out for them and pick them off by hand.
The disease pumpkins are most prone too are powdery mildew and it can spread really quickly in hot humid conditions. To try and control this disease you can use cows milk, sprayed on the leaves every two weeks with a solution of 1 part cows milk to 10 parts water. The good ladybirds identified by yellow and black bands and they eat the mildew, so don’t kill them. We also recommend watering in the morning, no overhead watering but watering at ground level to prevent the spores being splashed up onto the leaves.
Harvesting and storing
The best part of growing pumpkins, is harvesting them. You have watch them grow, no pests or diseases have got them and then you think, we don’t know when to harvest them. Well it takes between 3-4 months, they should be a nice color, sound hallow when you knock on them and the skin should be hard and not show any indentations if you press you finger nails into them. It is really important that you cut them off with at least 5-10cm of the stalk attached. This prevents mound entering into the pumpkin and helps to length their storage life.
Picking the right storage space is essential if you want to have pumpkin out of season. It needs to be well ventilated, no direct sun light and cool. It also needs to dry and not damp. The pumpkin also needs to be healthy, no breaks in the flesh and there should be no sign of mould. If there is, then eat it straight away, it won’t store.
Final tip to help them grow healthy and strong is to feed them fortnightly with a potash and liquid manure drink. Can be cow, sheep manure or worm liquid.
For pumpkins to grow successfully, they need to have rich organic soil, be in full sun, good weather and regular moisture. If you follow these simple guidelines and the weather is consistent neither too hot or too cold, you will have lovely healthy pumpkins which you will be able to store and eat and eat when it is out of season.