Watermelon 'Creamy Saskatchewan' (Citrullus Lanatus) Fruit Plant Heirloom, 10 Seeds

I bought these seeds and a mini greenhouse to try to grow watermelon seedlings. All of the seeds from other packets grew and are doing good outside in my garden, but 7 of the seeds from this packet never sprouted, and the 3 that did sprout are almost dead, less than a week later