In the northeastern United States, vegetable crop classes and growers' meetings are often held during winter months when field demonstrations are impossible. A pot-sized demonstration was set up in the greenhouse in May and Nov. 2002 as a student laboratory to show the effects of season extension materials on the early growth of winter squash. The treatments were black plastic mulch and rowcover, alone and in combination. The treatments were also placed on either a heated [18.3 °C (65 °F)] or unheated germination mat to simulate warmer and cooler spring soils. Butternut squash (Cucurbita moschata) was sown in 10.2 × 10.2 × 11.43-cm (4 × 4 × 4.5 inches) pots in soilless medium. The plants were grown and observed for 30 days, then harvested and weighed. The plants in the greenhouse grew as expected of plants grown under similar conditions in the field. Bottom heat, mulch, and rowcover had an increasingly greater effect on the growth of subsequent leaves as shown by comparisons of leaves 1, 2, and 3. Warmer soils tended to have the greatest effect on all measured parameters, but this was not as obvious in the May experiment as it was in the November experiment. Thus, this pot demonstration can be used in a student laboratory. The pots and plants are small enough to transport to and set up at winter growers' meetings as well.