[oldman]

If you're using the same heat mat for peppers and tomatoes that may be a contributing factor too. I'm the opposite of you as I usually have problems with peppers but my tomato problems are usually limited to seed not germinating. if it's way too old (more than 10 years).


If you don't have one you might want to pick up an IR thermometer at at auto parts store Or just use a digital meat thermometer if you have one of those. Tomatoes germinate best at between 75 AND 85 F. Up to 90 they get leggy unless they get about 14 hours of light. This is as much because they grow faster at higher temps. This is a good thing when they've been potted up or planted out. For the first few weeks higher temps contribute to skraggly plants that dry out too fast . Since peppers like higher heat and you don't have problems with them I'm thinking it's a factor for you.


I'd suggest trying to start a flat on the heat mat and leaving the dome off. It holds in both heat and moisture. You'll want to mist the flats two or three times a day to keep them damp/most but not wet. If you want to keep the domes on, try staring your tomatoes in a room that's 10 degrees cooler than the one you use for peppers. Heat mats aren't usually precision instruments and usually just claim to keep flats 20 degrees warmer than ambient room temp or something like that. So you need to control room temperature if you can't control the heat mat temperature.


For lighting I'd recommend getting an LED setup. There are a variety of sizes. Figure out how much you want to spend and get the best output you can afford. You can get a LED grow light that is around 750W and fiull spectrum for about $100. It's enough output for 4 1020 flats at once with potted up stuff surrounding them to take advantage of the extra light. I have a 270W model I got for $15 on eBay. It can do 2 flats because it can be put closer. You can get cheapies that are less than 100W for about 20 bucks retail, but you get what you pay for.