10″ x 20.75″ Vivosun Seedling Heat Mat (2-pack)

10″ x 20.75″ Vivosun Seedling Heat Mat (2-pack)

Frustration with seed starting is where many ambitious gardeners who don’t want to just go out and buy plants (not that there is anything wrong with that) throw in the towel. Soil temperatures that are too cold are the number one reason that seeds take too long (or completely fail) to germinate. Very few seeds need light to germinate (lettuce is a notable one that requires light), but all seeds need a minimum soil temperature before they set into action.

I had known about seedling heat mats for awhile before I finally started using them to start certain seeds. I experienced 20-40% germination rates with my hot peppers (which already have a longer than average germination period) before I started using these heated mats. The majority of my seeds rotted in the trays because the soil was moist and cool instead of moist and warm. I had already lost more than two weeks in my planting schedule by the time I realized that I needed to start over.

I had no luck at all getting my Indian and Chinese bitter melon seeds to germinate until I used these mats. I called the seed company, who sent replacement seeds as a courtesy and also suggested that I use a seedling heat mat. All 20 of the new seeds germinated because the soil reached the critical temperature required.

The 10″ x 20.75″ mat is designed for a standard 1020 tray that you see at the nursery or big box store. I place my heating mat directly on the wire shelf of my seed starting rack. Don’t place the mat directly on a concrete floor, as a giant mass of cold concrete acts as a heat sink, causing the majority of the heat to be absorbed by the floor rather than your seedling tray.

At only 18 watts per mat, the electricity these consume is negligible. The manufacturer does offer seedling heat mat kits that come with a temperature regulator, but I’ve never seen the need to adjust the temperature regardless of the vegetable or flower seeds I’m starting. Keep the growing medium moist (but not wet) at all times and you won’t have to worry about the temperature. Your seedlings can use all the warmth the mat will provide, but at the same time you’re not going to fry them either. In fact, until I see the seedlings emerge, I put the humidity domes on my trays to help boost the temperature and keep the soil from drying out.

These seedling heat mats are especially beneficial if you are starting peppers, tomatoes, basil, eggplants, and bitter melons. Considering their low cost to begin with and the fact that you can use them year after year, they are cheap insurance for maximizing your odds of growing out healthy seedlings that will be ready to transplant to the garden at the optimal time.

While these mats do come with a cinch-style storage bag, I don’t recommend rolling them up to store them, especially if you’re going to store them in a cold garage or outbuilding over the coldest months of winter. The thin plastic is much more likely to crack when you unroll it. I store mine flat on the top of my seed starting racks along with the rest of my supplies.