Growing Vegetables/Only a few pumpkins

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Question
Mike,

Live in central Iowa.

Planted pumpkins this year for the grandkids/neighbor kids but only got 3 good sized pumpkins and 1 smaller one from 3 plants. Don't remember the variety of the seeds but they were a "Jack-O-Lantern" type. Vines filled an area about 5'wide and 15'long and had so many blossoms earlier I thought I would need to thin out the pumpkins when they started developing, instead I got 4. What went wrong? Lots of blossoms but no pumpkins. By the way the 3 pumpkins are a perfect size for carving, wish I had about 12 more, luckily I didn't make any promises for pumpkins.

Mark

Answer
Mark, when pumpkins and other members of the squash family fail to produce fruit due to blossoms or young fruit falling off prematurely, it is usually an indication of one of two problems. Either your plants are not being fully pollinated, or they are receiving too much water.

If pollination is the issue, it is possible you need to attract more bees. If you do not have enough bees in the area, you can hand-pollinate the flowers of most vegetables by taking a Q-tip or small paint brush and transferring the pollen from the male flower to the female (the female always has a small fruit on the end). This must be done within one day of the female flower blossoming. To attract more bees, grow sunflowers, marigolds, cosmos, or some other bright annual in the immediate area.

One other possibility is that you are over-fertilizing the plants. Many of today’s water soluble fertilizers are very high in nitrogen. This results in lush foliage but often at the expense of a smaller harvest. Look for a fertilizer higher in phosphorus and potassium. Many companies now market products formulated especially for fruit-bearing vegetables such as tomatoes and squash. I would also recommend to add aged manure or compost to increase the concentration of natural phosphorus and to stabilize the ph levels of the soil.

In summary, remember to continue fertilizing with a low nitrogen fertilizer once every other week, and only supplement enough water to ensure a depth of 1.5” per week. Water only once or twice per week but very deeply. Shallow watering always results in poor root development and smaller harvests. Also, be sure to mulch heavily with straw or dried grass clippings around the plants to retain moisture and cool the soil.

Good luck, and have a great weekend.

Regards,

Mike

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Mike Mascio

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I have been an avid gardener since 1985 and an AllExpert volunteer since 1998. I specialize in soil preparation, seed starting and plant propagation, flowers, vegetables, and general landscaping. I am a strong advocate of the square foot method of gardening and the use of organic controls for pests and diseases.

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