Question: Can we grow giant pumpkins along the Central Coast?
Answer: The short answer is YES. Giant pumpkins can be grown in San Luis Obispo and all along the Central Coast. Giant pumpkins need between 120 and 150 days of warm weather and we have that. They love full sun and need some protection from wind and only a few pests. It is easy to grow a pumpkin that weighs 100 to 200 lbs. There are lots of secrets to grow a 500 or 1000 pound pumpkin.
The most common question asked at the annual contest at Mission Plaza is “How do you grow pumpkins that big?” The key is the seeds. You must have seeds from giant pumpkins grown the year before. Generic pumpkin seeds are easy to find at your local nursery but if you want premium giant pumpkin seeds with a pedigree, you might look on the Internet and pay a few dollars for one or two seeds that have monster parents!! Or, you can attend the annual pumpkin event at Farm Supply in San Luis Obispo on May 14 and receive a free giant pumpkin seedling.
Plant seeds as soon as the soil warms up, usually late April and early May. Before you plant, it will be best to work up the soil and add lots of organic matter such as compost or well composted manure, and perhaps some time-released fertilizer. If you are starting your seeds inside or in a container, they germinate best when near 80 degrees! When the plant emerges, protect it from late frost and from snails, slugs and earwigs.
As your main vine makes its long growth, it is best to cover the nodes (junction of the leaf and vine) with moist soil so the vine will send down secondary roots and anchor the vine. Your first flowers will be tall and beautiful male flowers. The female flowers will come later as the vine reaches 5 to 10 feet from where you planted it. The female flower will have the tiny fruit (your future giant pumpkin) directly under the flower.
Let your vine have two or three pumpkins until they reach the size of a volley-ball and then the hard part comes; you must remove all but the fastest growing one! Put a piece of plywood under this fast growing fruit and protect it from all critters and midday sun. Feed your pumpkin a well balanced fertilizer until your fruit is volley-ball size and then cut back on the nitrogen. Water is most critical now! Growers of the really big pumpkins all have secret formulas for getting their pumpkin to reach 1500 pounds and up! Everything you do must be directed at giving your one pumpkin all the energy from the roots. This includes constantly pinching off new little pumpkins. Some growers even recommend removing all of the tendrils daily so they don’t take energy from the big one. The annual Giant Pumpkin Weigh-Off will be held at the Mission Plaza on Oct. 20. There is no entry fee but you must complete an entry form to enter and win any of the nice prizes. Entry forms are available from any of the Farm Supply stores.