GTIYB
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Location: Freedom, CA USDA Zone 9b

Root temperatures for seedlings

Hello,
I will be starting my spring vegetables on heating trays in my garage this January. I have all of the germination temeratures for the veggies I'll be starting but was wondering if anyone knew what temperatures will be best for root development/overall health and vigor after the seeds have sprouted/before they are hardened/planted out.

Below is a list of the veggies I am planning on starting on the trays:

Artichoke
Soybean
Beetroot
Broccoli
Brussel sprouts
Cauliflower
Eggplant
Leeks
Lettuce
Okra
Peas
Peppers
Zucchini
Tomato
Strawberry
Swiss Chard

Any help/advice will be greatly appreciated!

Thanks in advance,
Matt

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Meatburner
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Joined: Sun Jun 17, 2012 2:00 pm
Location: SW MO zone 6b

Re: Root temperatures for seedlings

Please go back to your profile and put in your zone information. Without that, no one can help you if you are growing from seed in your garage. January here in zone 6 would still be freezing temps in my garage. Your state will be just as helpful as well.

DoubleDogFarm
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Re: Root temperatures for seedlings

Hardy vegetables such as spinach, lettuce, parsnips and onions require soil temperatures of at least 35 F. Once temperatures warm up to 40 F, vegetables such as peas, radishes, celery, turnips, broccoli, beets and cauliflower become viable. Most warm-weather vegetables such as tomatoes, corn, peppers, eggplants and summer squash require 60 F soil.

Gets you in the ball park :)

Eric

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rainbowgardener
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Re: Root temperatures for seedlings

Artichoke
Soybean
Beetroot
Broccoli
Brussel sprouts
Cauliflower
Eggplant
Leeks
Lettuce
Okra
Peas
Peppers
Zucchini
Tomato
Strawberry
Swiss Chard

It is a very mixed bag of annuals and perennials, warm weather crops and cool weather crops, stuff that is usually started from seed indoors and stuff that isn't. It really helps to sort it all out.

Cool weather stuff that I usually start ahead indoors (as Eric said this is climate dependent-- the longer growing season you have, the less need for starting ahead indoors): Broccoli, brussels sprouts, cauliflower.

Cool weather stuff that I would usually just plant directly in the ground: Beets (and other root crops, like carrots, which do not transplant well), lettuce, peas, swiss chard. Quick growing stuff does not benefit as much from the head start as the slower things.

Warm weather crops to start indoors: Eggplant, okra [note okra has heavy, hard seed coats which need to be soaked over night before planting], peppers, tomatoes. Zucchini is kind of optional. I do start them ahead indoors, no more than one week ahead of average last frost date, maybe at the average frost date. They need the soil well warmed up before they go in it. But they grow very fast, so many people just plant them directly in the ground once the soil is warm. Soy and other beans are fast growing warm weather crops that are usually just planted in the ground, when the soil is warm.

The artichokes are tender perennials and are tricky to grow in cooler climates, so it totally depends on where you are. Here's some info about them:

https://www.organicgardening.com/learn-a ... artichokes

Strawberries are almost never grown from seed. They are very slow from seed- the seeds take a month to germinate and then don't produce until at least the next year, maybe the third. Strawberry plants are sold everywhere very cheaply. They are perennials and need a bed of their own.

To me, one of the most important things to know in gardening, especially growing things from seeds, is when to plant what. If you start your broccoli too late, once the weather warms up, it will bolt and just produce flowers instead of heads. If you start your tomatoes too early, the plants will get too big and leggy waiting for good weather. People can give you approximations based on your area, but you will get better over time with experience of your particular climate/ micro-climate.

This is a very ambitious list that will require a lot of growing space. If you don't have a lot of experience in growing things, I would recommend scaling the list back a bit. It is always better to have success with a small plot of a few veggies, than start a huge garden and have it over-run with weeds & pests and get discouraged.

Have a great gardening year coming up! :)
Twitter account I manage for local Sierra Club: https://twitter.com/CherokeeGroupSC Facebook page I manage for them: https://www.facebook.com/groups/65310596576/ Come and find me and lots of great information, inspiration

PaulF
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Re: Root temperatures for seedlings

In my area of the listed items the only ones started from seeds indoors (my garage would not be warm enough until the same week plants would be planted outdoors anyway) would be tomatoes, peppers, cauliflower and eggplant. The rest get planted directly into the garden. You must be in a large number zone to be starting seeds in your garage in January.
Paul F

GTIYB
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Location: Freedom, CA USDA Zone 9b

Re: Root temperatures for seedlings

Hey all!

Thanks for all of the replies - I've gleaned a lot of great information from them. I really do appreciate it! I've updated my zone in my profile to give you guys a better idea of where I live.

Let me rephrase my question as I don't think I really explained myself very well: first of all, I won't be starting all of these species at the same time - the first seeds get started January 27 on the heating trays in my garage and the last seedlings will be planted out July 6. I have 8 different dates scattered throughout that time period where the three 72 cell trays on three different heating trays will be planted out. My gardening area is about 675 ft sq and I've already mapped everything out. I've been gardening for a few years now so I have a pretty good handle on what I can get away with (though I rarely err on the side of caution...!)

My original question was after my seeds have germinated, is there an ideal temperature I should lower my heating pads to before I plant them out? I'm not concerned so much with the timing of starting the seeds as I am concerned what temperature I should be running the heating pads after they have sprouted. I've already committed a good deal of thought to when my frost dates trend/average temperatures, I'm just wondering what temperature the seedlings will prefer before I harden them out.

My thinking is that 65 degrees F would be a comfortable temperature for the roots to develop before I plant them out in my garden. Rainbow Gardeners suggestion of categorizing the different cold weather and warm weather crops may be the route I take - I may lower the warm weather guys to 65 and take the cold weather off of the heating trays altogether.

Again, thanks for all your advice! I'm looking forward to posting more and more this new year. I'll be sure to upload pictures as I get things going. I actually currently have about 30 broccoli plants and probably an equal number of smaller cauliflowers - I'll upload some pictures soon. The broccoli should be ready to eat in a few days - the cauliflower got started a few weeks after the broccoli and haven't begun to form heads.

Thanks,
Matt

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rainbowgardener
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Re: Root temperatures for seedlings

To me, the heat pads are really just for germinating the seeds. Once the plants have true leaves, I take them off the heat mats. At that point the soil temp equalizes with the ambient temperature. In the winter, in our house, ambient is about 62 most of the time and 67 when we are home and up. It may not be ideal for everything, but it helps toughen them up to be more ready to go outside.

I only run two heat mats and I don't want to do any more, because they draw a lot of power, so everything has to come off the mats pretty quickly to make room for more.
Twitter account I manage for local Sierra Club: https://twitter.com/CherokeeGroupSC Facebook page I manage for them: https://www.facebook.com/groups/65310596576/ Come and find me and lots of great information, inspiration

GTIYB
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Joined: Thu Dec 26, 2013 4:40 pm
Location: Freedom, CA USDA Zone 9b

Re: Root temperatures for seedlings

Hey all,
Thanks so much for the replies - very, very helpful.

I think what I'll do is ween them off the heating pads in a week or so after they've germinated (gradually, like Marlin prescribed). I plan on giving everyone about a 7-10 days to germinate, then 7-4 days to ween them off of the heating pads/increase their light input from one bulb to two, then 7 days to harden them out. The exception would be the strawberries, which I'll give some the full 3 weeks to germinate with the heating trays on and, if they don't, I'll just plant the plugs in the garden and let nature take it's course.

Thanks again for everything. I'll keep you guys posted with how this polyculture experiment goes! Trying hard to incorporate as many plant families as possible to keep disease/pests down. Going to have 11 different families represented with my veggies, plus 11 varieties of flowers (though 4 are in the aster family, which are in the same family as the artichoke and lettuce I'm growing).

Thanks,
Matt

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applestar
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Location: Zone 6, NJ (3/M)4/E ~ 10/M

Re: Root temperatures for seedlings

If the temperature is at least 50°F I don't think you want to use the heat mat AT ALL for lettuce and peas. They don't really need it.

What is the outside temp in January? I think the peas should be sown directly in the ground soon as the ground has thawed. Use pea rhizobium inoculant. If it doesn't freeze where you are, then typical 72 day peas should be sown 80-90 days or more before you expect temps to get in the 80's when it will get too not for peas. If you have earlier maturing peas adjust accordingly. Peas take as much as 3 weeks to sprout if the ground is frosty. You can get them going earlier by pre-germinating them first, but I wouldn't grow them inside to any kind of seedling size -- they're too hard to handle.

Eric/doubledog has a neat rain gutter growing method for pea seedlings however.

Lettuce can germinate at 45°F (2-3 weeks) or higher (5-7 days around 70°F) but won't germinate in hot soil. They grow well with soil temp in the 50's and seedling leaves can take temps down to the mid-upper 20's as long as they are hardened. Unless you have slugs/snails, leaf lettuce is just as easy to sow directly. If you have short spring (like I do), then you do need to start head lettuce inside to give them a "head :P " start, but if you have long cool spring, then you may not need to.

Soybeans should also be sown directly in the ground. They need cooler 60's temp when setting pods but need the ground to be warm to germinate like all beans. Most likely around the same time as when the pepper seedlings are planted out. I think if you are pushing it, the ground will still be too cold at tomato planting time which is usually around 2 weeks earlier. Soak in de-chlorinated water for 4-6 hours and use appropriate soybean rhizobium inoculant.
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GTIYB
Newly Registered
Posts: 9
Joined: Thu Dec 26, 2013 4:40 pm
Location: Freedom, CA USDA Zone 9b

Re: Root temperatures for seedlings

Thanks, everybody, for your insights. I'll take them all to heart as I continue planning for Spring

fourfortytwo
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Joined: Wed Mar 25, 2015 2:43 pm
Location: ZONE 4B cental maine

Re: Root temperatures for seedlings

https://www.vegedge.umn.edu/mnvegnew/vol2/0400t1.htm

I think this chart is very helpful, I believe I got this link from this forum, I have a temp controller for my heat mat with a temp sensor and all, so I can hopefully dial it in perfect.
Zone 4B, Maine. Approx. 124 day growing season, 50% frost-free certainty May 14th-Oct 1st. Ten 4'x8'x15" raised beds with PVC hoops attached with lightest weight row cover/bird netting/30% shade cloth, depending.



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