The Sugar Baby watermelon, a popular heirloom variety, is often called an “icebox” melon because its small, compact size makes it ideal for refrigeration and is highly suitable for small gardens or container growing. This cultivar is prized for its early maturity, typically producing fruit in about 75 to 85 days from germination, which is faster than many larger varieties. The melons usually weigh 6 to 10 pounds and feature deep red, sweet flesh. Its high sugar content, measured by a Brix rating of around 10.2, contributes to its superior sweetness and enduring popularity among home gardeners.
Germination and Seedling Establishment
Watermelon seeds require consistent warmth to successfully sprout, with optimal soil temperatures for germination ranging between 80 to 90°F. Gardeners often start seeds indoors about three to four weeks before the last expected frost date to get a head start on the growing season. Seeds should be sown at a shallow depth of about one-quarter to one-half inch in well-draining seed starting mix.
Germination typically occurs within 3 to 10 days, and using a heat mat can significantly increase the rate. Once seedlings emerge, the soil temperature can be slightly reduced to the mid-70s, and watering should be reduced but maintained. When the first set of true leaves appears, seedlings should be thinned to the strongest plant per pot to prevent root disturbance.
Seedlings started indoors must undergo a “hardening off” process before transplanting, gradually exposing them to outdoor conditions like wind and direct sun. This process toughens the plant tissue, preparing them for the permanent growing site. Transplanting should only occur when the outdoor soil temperature is reliably at least 70°F and all danger of frost has passed, as cold soil below 50°F will significantly slow growth.
Vine Development and Vegetative Care
The vegetative phase begins once the seedling is established in its permanent location and is characterized by rapid vine expansion. Sugar Baby watermelons thrive in rich, loamy, well-draining soil that has been heavily amended with organic matter like compost or aged manure. The ideal soil pH is slightly acidic to neutral, typically ranging from 6.0 to 7.0.
During this vigorous growth period, the plant needs consistent, deep watering to support its extensive root system and large leaves. Water should be directed at the base to keep the foliage dry, minimizing the risk of fungal diseases like powdery mildew. While allowing the top two to three inches of soil to dry out between waterings is acceptable, the plant should never be allowed to completely dry out overnight.
Nutrient management initially requires a nitrogen boost to fuel vine and leaf growth, typically applied when tendrils appear. As the plant nears the flowering stage, the fertilization focus must shift to formulas lower in nitrogen but higher in phosphorus and potassium to support flower and fruit development.
Although Sugar Baby is compact, the vines still spread four to six feet wide. Proper spacing of 24 to 36 inches between plants allows for good air circulation. While ground-growing is suitable, some gardeners opt for vertical trellising, which saves space and improves airflow.
Flowering, Pollination, and Fruit Set
Watermelon plants are monoecious, producing separate male and female blooms on the same vine. Male flowers generally appear first and are identified by their slender stem, lacking any swelling at the base. They provide the necessary pollen for fruit production but drop off the vine after opening.
Female flowers appear later and are distinct, featuring a miniature, swollen bulb, which looks like a tiny watermelon, located between the flower petals and the vine. This swelling is the ovary, which must be fertilized to develop into a mature fruit. Both flower types open for only a single day, usually in the morning, making timing critical for pollination.
Pollination is primarily carried out by bees, which transfer pollen from the male flowers to the stigma of the female flowers. If natural pollinators are scarce, growers can manually pollinate by transferring pollen from a freshly opened male flower directly onto the sticky center of a female flower. Successful pollination leads to “fruit set,” where the tiny ovary rapidly swells, marking the transition from flower to developing melon.
Maturation and Determining Ripeness
Determining the exact moment to harvest a Sugar Baby watermelon is challenging, as the fruit does not continue to ripen once picked. Maturation typically takes 75 to 80 days from planting or about five weeks from a successful fruit set. Growers rely on a combination of visual cues to ensure optimal sweetness.
Visual Cues for Ripeness
The most reliable indicator is the change in the color of the “ground spot,” the area where the melon rests on the soil. This spot starts white or pale green and matures to a deep, creamy yellow or tan color when ripe. A second key sign is the tendril closest to the fruit stem; when the melon is ripe, this curly tendril will turn brown and dry out completely. The rind also changes subtly, losing its initial glossy sheen and developing a duller, matte appearance as it matures.
Sound Test
A third, though more subjective, method is the sound test. A ripe melon will emit a deep, hollow sound when tapped, similar to a drum, while an unripe one sounds dull or flat. Once all signs indicate ripeness, the melon should be cut cleanly from the vine, leaving a few inches of stem attached.