I have 3 trays of seedlings going do far and 3 more to be planted. One tray has tomatoes, peppers, eggplants, tomatillos, and ground cherries. It is on a hearing pad to keep the soil temperature up until all of the seeds germinate.
Another tray has herbs. These I started without any extra heat but I suspect that some of the herbs may have been a little quicker to germinate with the added soil warmth.
The last tray has veggies that will tolerate cool weather. They will be moved outside much sooner than the warm weather veggies so I have them sitting in an open window today to start getting accustomed to outdoor conditions. It will still be a few weeks before they go outside and some aren’t even germinated yet. This tray might have been a little faster getting started with some bottom heat but since I only had one heating pad and the tomatoes, peppers and other warm weather crops really need the heat to germinatethey are the ones that got it.
The seedlings inside have lights hung just a couple inches above them. The lights will be moved up as the plants grow. As soon as everything in the warm tray germinates I will be starting another tray of warm weather veggies, mostly more tomatoes. My grow lights are just shop lights with full spectrum bulbs. There is also some ambient light from several windows in the room.
I think one of the biggest mistakes people make when starting seedlings indoors is expecting a window sill to have enough light for seedlings. A greenhouse window or bay window might if it is on a sunny side of the house but even then you might do better by using artificial lighting to extend the daylight hours for your seedlings. I keep lights on mine for 16-18 hours a day. This helps to keep they from getting long and spindly. I have the seedlings in my bedroom with all of the lights plugged into a surge protector. I simply turn the strip on when I get up and of just before I climb into bed. There are timers you can buy that do this for you but I do just fine doing it on my own.
Another mistake people often make is not providing bottom heat for seeds that need high soil temperatures to germinate. In general plants that are grown in the summer, not early spring or fall gardens, will appreciate some heat from underneath. I am using a heating pad but another good spot is in top of the refrigerator. The up side to that ids not having to buy anything but the downside is that seedlings out of site may be out of mind. Trays should be checked daily and lights added as soon as the first seedlings start to pop their heads up through the soil. The trays should be covered to keep moisture in until germination but shortly after that the cover needs to be removed. Unless you are prepared to rig lighting over the top of your refrigerator you will need to pull the tray down before all of the seeds have germinated. Most of the summer seeds like the soil temp to be 80 or so. Even if you do keep your home 80 degrees in the winter, air temperate and soil temperature aren’t the same thing. While cool weather crops will generally tolerate cooler soil during germination even they will do poorly if the soil temperature is too low. I have had pretty good luck with them germinating at room temperature but many warm weather crop seeds will rot or mold without the bottom heat.
That is all of my seed starting wisdom for today. I’m fairly new to all of this myself so I would love to hear from you. What has worked for you? What hasn’t?