Directly planting or sowing of pumpkin and winter squash seeds is usually done one of two ways, either by starting seeds as transplants to be planted later or by direct planting. There are several advantages to direct planting or sowing of pumpkin seeds (the term pumpkin being used here interchangeably with winter squash), including: less effort/work as is involved in transplanting, less stress on seedlings and the seedlings do not have to be hardened off. Direct planting of seeds is beneficial for planting large acreage fields and is often performed through mechanical means on large commercial farms, but can be performed easily and effectively by hand in home gardens.
It is however, a little bit more difficult to germinate pumpkin seeds directly sown as it is hard to manage and maintain proper environmental conditions. First, after the seeds are planted, the soil must remain moist, not saturated throughout the 7 to 10 day germination process. Second, a constant temperature of around 80° F with fluctuations of no more than 10° above or below is desired. Third, the seeds, once planted should be protected from animals, most notably squirrels and birds, as they will find, dig up and eat seeds right out of the ground. It of course goes without saying that germination cannot take place unless your winter squash seeds are viable. These considerations should be taken into account when planting so that you will achieve germination and planting success.
Here is an outlined procedure for directly planting pumpkin seeds to help you ensure adequate germination.
Dig a hole at each hill location about 8 inches across by 8 inches deep. Put in at the base a small handful, about 2 tablespoons worth of 10:10:10 granular fertilizer, this help kick start plant growth later on.
Backfill soil into the hole up to ground level. Adding some organic matter or rich topsoil to this backfill soil is a good idea. Here where you are filling back in the hole, you will do so to the soil level, not below as a depression or above as a mound as this could cause watering and moisture problems for the plant in the future. Also note that this loosened soil will provide a place for the winter squash seedling roots to easily expand and grow in.
Place 4 to 5 seeds at the hill location at the center of the replaced soil, ½ to ¾ of an inch below the surface uncovered. Pour several ounces of water over the seeds, then cover them with dry soil, this will help in keeping moisture around the seeds. If you cover the seeds with soil then pour water over them, the air and sun will dry out the soil above the seeds hardening it making it more difficult for the seed to break through the soil surface. Here you want to use a few extra seeds in each just to account for the increase in the variability of environmental conditions to make sure you have at least 2 plants per hill and don’t have to replant later. Placing a small flag or marker at each hill location is a good way to keep track of the pumpkin seedling locations.
To limit animals scavenging for seeds, try placing thin paper napkins held down at the corners by rocks (to avoid the wind blowing them away) over each hill. This seems to work well at keeping them away. Remove napkins once seedlings emerge as by this stage animals will no longer be interested in them. You can also perform this same process with plastic shopping bags to warm soil around seeds during cooler temperatures to aid in germination.
Starting Plants From Seeds; Horticulture Information Leaflet 8703
Erv Evans, Extension Associate, Horticultural Science; Frank A Blazich, Professor, Horticultural Science; North Carolina State University
North Carolina State Cooperative Extension Service
Retrieved from: http://www.ces.ncsu.edu/depts/hort/hil/pdf/hil-8703.pdf