Seed starting
To start seeds indoors you need small cells or pots with drainage holes, a sterile seed-starting mix and strong light. University of Minnesota Extension says a windowsill is a poor spot, since it can be the coldest place in the house at night and the hottest by day. It adds that bottom heat helps most seeds sprout sooner (UMN Extension).
Heat mats, thermostats, trays, humidity domes and lit seed-starting shelves. Compare size, power and how many seedlings each one handles.
7 of 7 seed starting match
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Questions people ask
Do I need a heat mat to start seeds?
It helps. University of Minnesota Extension says potting mix can run up to 5°F cooler than the room, and most seeds sprout sooner with warm mix. Bottom heat can also help prevent damping off. Don't plug a heat mat into the timer for your lights (UMN Extension). Utah State Extension suggests pairing a heat mat with a thermostat so seed containers don't get too hot (USU Extension), and Penn State Extension says the same (Penn State Extension). The mats we list don't include one, per their maker.
Do seedlings need a grow light?
University of Maryland Extension says light from a window is seldom enough for strong seedlings. It suggests keeping them 1 to 2 inches below a fluorescent fixture for 14 to 16 hours a day (UMD Extension). Compare grow lights.
What mix should I use for seeds?
University of Minnesota Extension recommends a commercial seed-starting mix, usually peat and vermiculite with no true soil. It's sterile, light and free of weed seeds (UMN Extension). University of Maryland Extension says never to use garden soil for transplants (UMD Extension).
When do I take the humidity dome off?
University of Minnesota Extension says to remove domes when the seedlings are tall enough to touch them (UMN Extension).
When do seedlings need bigger pots?
University of Maryland Extension says the best time is about when the first true leaves appear, and that leaving seedlings in the seed flat too long is a common mistake (UMD Extension). Penn State Extension gives the same sign (Penn State Extension).
When should I start seeds indoors?
Follow the seed packet, and count back from your last frost date. University of Minnesota Extension's table, written for Minnesota, keeps tomatoes indoors 5 to 6 weeks and peppers about 9 weeks (UMN Extension). Check your area: USDA keeps a directory of state extension services with local frost dates.