Growing Watermelon

Best Planting Times for Watermelons in California

Planting MethodActivityRecommended Dates
Outdoor PlantingIndoor Seed StartingMarch 15 – April 15
Transplant OutdoorsApril 30 – May 15
Greenhouse PlantingYear-roundAdjust planting based on temperature control in the greenhouse

Planting Conditions

Watermelon Planting Conditions

California’s warm climate, especially in the southern regions, is ideal for watermelon cultivation. The USDA Hardiness Zones range from 5b to 10b, which allows for a lengthy growing season suitable for this heat-loving fruit.

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Useful Tools for Starting Watermelons Indoors

Using the right tools can save you time and increase your success rate.

Seeds

Quality seeds lead to better germination and healthier plants. Starting with high-quality seeds gives your watermelons the best chance to thrive from the beginning.
5 pack of different Melon Seeds
Browse Watermelon Seeds on Amazon

Planting Trays

Planting trays help you organize your seedlings and ensure they have enough space to grow before you transplant them outdoors. This makes the process more efficient and increases the chances of strong, healthy plants.
Planting Trays Image
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Grow Lights

Grow lights are essential if you don’t have enough natural sunlight. They provide your seedlings with the light they need to grow strong and healthy, even in less-than-ideal conditions.
Grow Lights Image
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Seed Starting Soil

Using light, fine soil specifically designed for seed starting helps young roots establish quickly and promotes healthy growth. It’s an easy way to give your seedlings the best start possible.
Seed Starting Soil Image
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Greenhouse Growing

In California, where high temperatures can promote vigorous growth, a greenhouse helps manage heat and prevents plant stress during peak summer months. Greenhouses extend the growing season, allow for more controlled watering and feeding, and provide protection from pests and diseases, optimizing the success of watermelon cultivation.

Consider investing in a 10×12 FT Greenhouse priced at $1,199 to ensure your watermelons thrive in a controlled environment.
Greenhouse Image 1
Greenhouse Image 2
Check the latest price on Amazon.

Fertilizer

For optimal watermelon growth in California, supplementing with fertilizer can ensure abundant and healthy harvests. Quality fertilizer helps replenish nutrients in the soil and promotes vigorous plant growth.
Fertilizer Image
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Plant watermelons outdoors in California approximately 1-2 weeks after the last frost date, ensuring the soil is warm enough for optimal growth.

Average Last Frost Dates for California’s Major Cities

CityAverage Last Frost Date
Los AngelesMarch 15
San DiegoMarch 10
San FranciscoApril 1
SacramentoApril 15
FresnoApril 5
Long BeachMarch 25
OaklandApril 10
Santa AnaMarch 20
BakersfieldApril 1
RiversideMarch 30

Disclaimer: Frost dates are average estimates, and actual conditions may vary. It is recommended to monitor local forecasts and adapt planting decisions accordingly.

Other planting guides for California:

Kale Planting in California

Broccoli Planting in California

Pumpkin Planting in California

Any questions on Growing melons? Visit our forum to discuss: Growing melons.

Starting Watermelons Indoors

In California, begin indoor watermelon seed starting from March 15 to April 15. This timing allows for healthy seedlings that are ready for outdoor transplantation starting in late April to early May, once the risk of frost has passed.

Transplanting Watermelon Seedlings

Transplant watermelon seedlings outdoors from May 1 to May 15, ensuring that the soil temperature is consistently above 70°F. Space the seedlings 36 inches apart in rows with at least 6-8 feet between rows to accommodate their sprawling habit and ensure optimal growth.

General Care and Maintenance

Watering

  • Provide consistent and deep watering to keep the soil evenly moist during the growing season, especially in California’s warmer climate.
  • Water at the base of plants to minimize leaf wetness, which helps reduce the risk of fungal diseases.

Fertilizing

  • Apply a balanced fertilizer at planting time and again when the first fruits appear. Mixing in compost before planting can significantly enhance soil fertility and structure.

Pest and Disease Management

  • Keep an eye out for common pests like aphids, cucumber beetles, and powdery mildew. California’s warm environment can encourage pest activity, so vigilance is necessary.
  • Employ organic or integrated pest management methods to protect watermelon plants from pests and diseases.

Harvesting

  • Harvest watermelons when they achieve the desired size and color, indicated by a dull finish on the rind and the tendril nearest the fruit turning brown. Regular harvesting encourages continuous growth and maximizes yield.

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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