Question
I am new to growing veggies from seeds.  I started my own little green house last spring.  It was a plastic tray with little pots, a plastic cover and a heating pad for underneith.  I didn't have many problems with the plants sprouting, but rather keeping them alive after they had sprouted.  Many of them just wilted.  I kept them watered and only left the heater on at night because they were warmed during the day by the sun.  I planted eggplants, bell peppers, tomatoes (various varieties of each), and various herbs.  Given that all plants thrive in different temperatures, what would be the best temperature for my seedlings?

Also, i would like to know when is the best time to start my seeds indoors.  I live in south eastern pennsylvania.  I also have no idea when the last frost date is, so i was wondering where i could find that out.

thanks for your help.

Answer
Crystal, the best time to start seedlings is approximately 6 weeks prior to your last expected frost date.  For your area, the last frost date is around mid-May, so you need to start your seeds the first week of April.

It sounds like your seedlings developed a common disease called "damping-off".  This disease is very prevalent when the soil is not sterilized or if air circulation is poor.  That is why garden centers continually run fans in their greenhouses. Damping-off is a disease that hits the seedlings suddenly.  One day they look perfectly healthy, and the next day they fall over and die.  There are numerous studies available on the web that will give you even more detailed information on this disease.

To prevent this disease, you need to use a sterile starting mix.  You can find these at any reputable garden center.  You also need to remove the plastic cover immediately once the seeds first germinate.  Leaving the cover on reduces air circulation and causes the plants to overheat.

One other possibility is overwatering.  Excess water can prove fatal to young seedlings by drowning their delicate roots.  This prevents the seedling from drawing oxygen and nutrients from the soil.  The roots eventually rot and the seedling dies.  Only water enough to keep the soil slightly moist.  I always water from the bottom and remove the remaining water in the tray after 2-3 hours.

The ideal temperature for growing plants from seed is 72 to 75 degrees.  Slightly cooler will not hurt, but it will delay germination by a few days.  Once they sprout, any temperature over 65 degrees is acceptable.  The warmer temperatures are necessary only when the plants are ready to bloom and produce fruit.  By that time, they are already in the garden where temperature is no longer an issue.

I hope this answered your question.  Please write again if I can ever be of assistance.

Regards,

Mike