starting time

encore · March 17, 2016

quick question here (i hope) last year i left the heat mats going under the tomato seedlings until they were over 6 inches tall and potted them up to 4 and some 6 inch pots. now my question is seeing that i'm going to shut the heat mats off after they sprout (as i have seen on here to do) to keep from getting too leggy and hopefully get stockier plants, do they grow alot slower doing it this way? if so should i start my seeds sooner than i planned on? or won't that matter that much? thanks----tom

KarenO · March 17, 2016

Depends on how cool they are. They will grow slowly if they are cold, temps in the 50's for example. At normal house temps say around 70 degrees and in good light they will grow fast. You shouldn't need to start them any earlier because you intend to remove the bottom heat after germination. They don't need it after germination and as you mention it can make them leggy and weak to leave it on. I would start them at your normal time.
Best wishes for a great season!
KarenO

Ricky Shaw · March 17, 2016

Best scenario for sprouts is top heat from a light source, close enough to warm the area, but not so close to burn the plants. I like 24/7 and 78F, and after getting a 2nd set of true leaves I reduce lighting to 16on/8off with 70's F days and 60's nights being my preference.

What's your light source? And, south windows are fine even, just have to be mindful of temps and have a longer time frame to work with.

Dozens of variables and everyone has their own twists, just keep reading.

encore · March 17, 2016

i've got 3 floresent fixtures with 2 full spectrum bulbs each, i've been using them heat mats, and a fan, the last couple of years now, i plan on starting a couple weeks later than last year , because they got so big (and alot of trips up and down the stairs to bring them outside to harden off. lol) so i was basicly wondering as i stated above about not using the heat mats after they sprout, if it'll take much longer or not for them to reach potting up size, as compaired to last year? it's somewhere between high 50's and low 60's in the basement.----tom

encore · March 17, 2016

or do they grow the same leaf wise but just shorter and stockier?

Merediana · March 17, 2016

Depends all on heat and light. If it is too cold, they'll grow slowly, but if they are in a normal, heated room at around 70°F they'll grow fast, especially when under growing lights that rise the temperature even higer or behind a window (here it is still very cold outside but with direct sunlight I've 80°F behind the window). If they don't get enough light, they'll get tall but weak, if they get enough light, they'll grow nice and stocky.

Be careful with the heat, if you can't provide enough light they'll get leggy VERY fast. I had a few days with next to no sunlight due to the bad weather and you really see the difference to the plants under my growing lights... Even though on sunny days you get a better light intensity from the sunlight than from my T8 light bulbs....

I'd only use a heating mat for seedlings when your rooms are quite cold.

encore · March 17, 2016

i keep the lights about 1/2 inch above them.

March 17, 2016	#1
encore Tomatovillian™ Join Date: May 2015 Location: wisconsin Posts: 536	starting time quick question here (i hope) last year i left the heat mats going under the tomato seedlings until they were over 6 inches tall and potted them up to 4 and some 6 inch pots. now my question is seeing that i'm going to shut the heat mats off after they sprout (as i have seen on here to do) to keep from getting too leggy and hopefully get stockier plants, do they grow alot slower doing it this way? if so should i start my seeds sooner than i planned on? or won't that matter that much? thanks----tom

March 17, 2016	#2
KarenO Tomatovillian™ Join Date: Oct 2012 Location: Vancouver Island Posts: 5,931	Depends on how cool they are. They will grow slowly if they are cold, temps in the 50's for example. At normal house temps say around 70 degrees and in good light they will grow fast. You shouldn't need to start them any earlier because you intend to remove the bottom heat after germination. They don't need it after germination and as you mention it can make them leggy and weak to leave it on. I would start them at your normal time. Best wishes for a great season! KarenO

March 17, 2016	#3
Ricky Shaw Tomatovillian™ Join Date: Aug 2015 Location: Zone 6a Denver North Metro Posts: 1,910	Best scenario for sprouts is top heat from a light source, close enough to warm the area, but not so close to burn the plants. I like 24/7 and 78F, and after getting a 2nd set of true leaves I reduce lighting to 16on/8off with 70's F days and 60's nights being my preference. What's your light source? And, south windows are fine even, just have to be mindful of temps and have a longer time frame to work with. Dozens of variables and everyone has their own twists, just keep reading.

March 17, 2016	#6
Merediana Tomatovillian™ Join Date: Feb 2016 Location: germany Posts: 190	Depends all on heat and light. If it is too cold, they'll grow slowly, but if they are in a normal, heated room at around 70°F they'll grow fast, especially when under growing lights that rise the temperature even higer or behind a window (here it is still very cold outside but with direct sunlight I've 80°F behind the window). If they don't get enough light, they'll get tall but weak, if they get enough light, they'll grow nice and stocky. Be careful with the heat, if you can't provide enough light they'll get leggy VERY fast. I had a few days with next to no sunlight due to the bad weather and you really see the difference to the plants under my growing lights... Even though on sunny days you get a better light intensity from the sunlight than from my T8 light bulbs.... I'd only use a heating mat for seedlings when your rooms are quite cold.