Do I Need to Prune My Pumpkins?

Growing Pumpkins

• Pumpkins are members of the cucurbit plant family, along with winter squash, watermelons, cantaloupe, cucumbers and summer squash -- sun-loving vines that can take up space. Work well-rotted manure into good garden soil before planting. Despite the tough rinds of mature pumpkins, plants are very tender, unable to tolerate cold. Plant pumpkins in full sun after all danger of frost is past in spring and the soil is fully warm. Irrigate during dry periods and mulch to conserve soil moisture and deter weeds. Avoid using pesticides and herbicides that may harm bees, because your vines need bees for good pollination.

Managing Runners and Side Shoots

• Secondary vines, known as runners, grow out from the main vine along its length -- something to encourage -- though you want to direct or "train" runner growth away from the main vine and from fruit. Prune off any tertiary vines, or offshoots of runners, to direct plant energy toward fruit growth.

Pruning Support Vines

• Beyond trimming away any tertiary vines, you also want to limit the reach of each vine's growth for the benefit of the plant as well as its crop. This pruning encourages new, bushier foliage growth -- more secondary and tertiary vines -- closer to the pumpkins, where it most benefits them. Prune the main vine when it extends 10 or 15 feet beyond the last fruit you plan to keep on the plant. Similarly prune secondary vines or runners when they reach 10 or 12 feet. Trim away tertiary vines again. Continue to limit outer growth as much as possible to encourage fruit development.

Encouraging Secondary Roots

• Secondary plant roots develop at the base of each leaf stem all along the vine, a plant habit you can encourage by mounding soil or compost there -- burying those sections of vine -- and irrigating occasionally if rains are rare. Secondary roots help anchor the plant against windstorms and other physical stress that may damage vines, but more importantly they allow the plant to draw both nutrition and water from multiple areas. Near pumpkins, however, try to discourage secondary roots, because they may anchor the vine to the ground so tightly it won't be able to move as the pumpkin grows, causing stem stress or breakage.