Growing Watermelon

Watermelon Planting Dates in Wisconsin

Planting MethodActivityRecommended Dates
Outdoor PlantingIndoor Seed StartingMay 1 – May 15
Transplant OutdoorsJune 1 – June 15
Greenhouse PlantingYear-roundAdjust planting based on temperature control in the greenhouse

Planting Conditions

Watermelon Planting Conditions

Wisconsin’s climate features a mix of hot summers and cold winters, making the growing season for watermelons relatively short. With USDA Hardiness Zones typically between 3b and 5b, it’s important to plant watermelons after the last frost date and when the soil temperatures are at least 70°F for successful growth.

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Greenhouse Growing

In Wisconsin, using a greenhouse offers several advantages for watermelon cultivation, especially considering the shorter growing season. A greenhouse allows for temperature control, protects plants from unpredictable weather, and extends the growing season to produce earlier and higher yields.

Fertilizer

For optimal watermelon growth in Wisconsin, using fertilizer can enhance nutrient availability in the soil, which is essential for healthy plant development and fruit production.
Fertilizer Image
Check out Fertilizer on Amazon

Other planting guides for Wisconsin:

Broccoli Planting Dates in Wisconsin

Pumpkin Planting Dates in Wisconsin

Tomato Planting Dates in Wisconsin

Any questions on growing watermelons? Visit our forum to discuss: Gardening Forums.

Starting Watermelons Indoors

In cities like Madison (Zone 5b), begin indoor watermelon seed starting between April 15 and May 15. This timeline ensures healthy seedlings ready for outdoor transplantation starting from late May to early June, after the last frost has passed.

Transplanting Watermelon Seedlings

Transplant watermelon seedlings outdoors from June 1 to June 15, ensuring the soil temperature is consistently above 70°F. Space the seedlings 24-36 inches apart in rows that are at least 6-8 feet apart for optimal growth.

General Care and Maintenance

Watering

  • Provide consistent and deep watering to keep the soil evenly moist, paying special attention during hot spells typical in Wisconsin’s summer.
  • Water at the base of plants to avoid wetting the foliage, thus minimizing the risk of fungal diseases.

Fertilizing

  • Apply a balanced fertilizer at the time of planting and again when fruits begin to form. Incorporating compost beforehand will boost soil fertility and structure.

Pest and Disease Management

  • Regularly check for common pests such as aphids, cucumber beetles, and powdery mildew. Maintaining vigilance is key due to Wisconsin’s varying humidity levels.
  • Adopt organic or integrated pest management strategies to safeguard watermelon plants from pests and diseases.

Harvesting

  • Harvest watermelons when they are fully matured, indicated by a dull skin and a hollow sound when tapped. Regular harvesting ensures you enjoy sweet, ripe fruit at its peak.

The importance of good soil

Before starting to grow it is important to take a step back and find the condition of the soil in your garden,The optimal soil is a blend that includes the mineral-rich dirt along with organicrich organic matter that plants need to thrive.


In my garden I try to compost as mutch as possible, so I can mix in the nutrient ritch compost in my soil. I use both hot composting of food scraps and cold composting of all organic garden “waste”..
If you dont have the time or space for composting, it is possible to get compost ready to use in garden centers and Community Composting.
You can read more on Community Composting here: https://www.epa.gov/sustainable-management-food/community-composting

If you are uncertain of the quality of your soil, you can get easy to use soil tests at amazon for 17 dollars. Check latest prices here: Soil testing kit.

Also remember to check out how much sunlight your growing area gets, and that the rain drains well. If you treat your soil well and plan you crops according to your climate you will succeed with any plant you want.

The satisfaction when you harvest your own produce is well worth the time you put in 🙂

BeeJay
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