calculating time to start seeds, if you start them outside

Need2SeeGreen(10 (SoCal))February 7, 2013


Sorry if this is a basic question, I snooped around in several forums and didn't see this exact issue.

I want to start a bunch of tomatoes from seed, but I grow my seedlings outside (no space inside).

I know you are supposed to calculate back from your last frost date, to know when to "plant out," and thus when to start the seed, but since mine will be "out" the whole time, does that make a difference?

I believe normally you are supposed to get your last frost date, then count 6-8 weeks backward. Should I just stick with that to be safe?

I garden on a patio that has warm spots, usually even when it's cold.

Thanks for any suggestions!

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Tomato seeds need heat to germinate. 80 degrees is optimimum. Definitely do not start them now - it's supposed to be very cold in LA this weekend. You can buy waterproof heat mats at the garden shops and put your seedling trays on them.

In terms of length of time to start seeds outdoors I would say it will totally depend on the weather and whether or not you provide heat.

In LA you can plan to plant outside around the end of March or early in April so this is the time to start seed indoors.

Hope this helps!

    Bookmark   February 7, 2013 at 9:08PM
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As long as they are protected from frost and get some bottom heat to germinate your tomato plants should be ok,I have tomato plants growing right now and they are about 4 inches.Use a good dome cover or make a plastic mini green house I use wire to raise it and keep it tightly covered and if too hot give a little shade also.

    Bookmark   February 8, 2013 at 12:19AM
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A pic of my toms.

    Bookmark   February 8, 2013 at 10:42PM
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Need2SeeGreen(10 (SoCal))

Thanks, Laura and Cal Mario!!!

That was very helpful. Sometimes there are so many variables that I get confused. I'm not sure what the weather's going to do, so I think I'll do some more research and think about it more.

Cal Mario, your plants look wonderful!!! Very inspiring.

    Bookmark   February 8, 2013 at 11:31PM
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MaryMcP Zone 8b - Phx AZ

Nice tomato forest!

Need2See....the more definitive answer is: the soil needs to be 65 to 75 degrees for tomato root activity. Otherwise the plant will stale its growth until that soil temperature is achieved. You can help that process along with a cold frame, or a 'red-neck' cold frame, an old window or french door placed over the garden bed. Or even plastic bottles filled with water and placed on the spot you will plant the seedling. Then, once planted, surround the plant with water filled bottles. The water is warmed by the sun and the heat dissipates downward to the soil. I'm going to try usig the 'bladder' from box wine refilled with water. Talk about 'red-neck'!! :-)

    Bookmark   February 9, 2013 at 7:07AM
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I have been growing tomato plants for a number of years and the seedlings don't need high temperatures like peppers do,they are happy as long as there is some daytime temperatures that warm my greenhouse during the day and mine have been growing even in the 30-40 degrees at night,here in the San Joaquin and even 20's a few nights as long as they were protected from frost I did give them a few extra hours of florescent light during January but not anymore.And I used bottom heat for starting the seedlings but that was the only heat I used.Good luck with yours!

    Bookmark   February 10, 2013 at 12:58AM
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MaryMcP Zone 8b - Phx AZ

cal_mario, yes, I understand that point and you used bottom heat, like a heat mat. I start seedlings indoors using heat mats too - when starting seedlings. I interpreted the question as relating to transplanting into the garden. Need2SeeGreen does not have a greenhouse or room indoors and wants to direct sow. That was my interpretation of the question.

Happy Gardening!!

    Bookmark   February 10, 2013 at 6:16AM
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Seeds are cheap, so there isn't much to lose.

I know you said you don't have room inside, but a week or two before your last frost date I'd plant some more seeds for insurance (planting them a week or two before the frost date won't require a large setup with lights...n i suspect everybody has room on their DVR or computer for a couple seed cups).

    Bookmark   February 10, 2013 at 10:53AM
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I agree with the poster above (cal_mario) you can grow your tomatoes in cooler temps. Here is a picture of mine. Those white bins in the back is where i am going to be growing my tomatoes. There is a few plants already growing in there and they don't care if the temps get down to the 30's. Anything under 30F they will die. Anything above no problem.

    Bookmark   February 10, 2013 at 6:11PM
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Need2SeeGreen(10 (SoCal))

Thanks so much, everyone!!!

This was helpful. I think I will start them now, or maybe a few each week, and if I set the cups on the patio floor, it should hold enough heat that they should be okay.

    Bookmark   February 12, 2013 at 5:07PM
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carolync1(z8/9 CA inland)

It might be useful to others if you put your Sunset garden zone in your personal information. Near the coast, there is "June gloom" to think about. Weather patterns may favor different planting schedules than further inland. The flavor of various cultivars may be better in warm vs. cool ripening weather. I got some good Cherry Chocolate tomatoes in December here, but I was not particularly impressed by their flavor in the heat of summer. This is the reverse of the flavor/weather profiles of some other varieties.

Also, you might get some pointers from the Winter Sowing forum if you're planting outdoors.

Here is a link that might be useful: Winter Sowing Forum

    Bookmark   February 15, 2013 at 12:35AM
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add 8 weeks to DTM

    Bookmark   February 16, 2013 at 1:23AM
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Need2SeeGreen(10 (SoCal))

Thanks for asking! I'm not sure exactly what my zone is. When I look at the map, I am in a green area that says, 22-24. Unless I am looking in the wrong place. I am in inland or central LA, where it can get pretty hot, but, not as hot as the Valley. Or Pasadena. And on a patio that with a 4 foot wall, so it gets extra, extra hot. So you're right that it's a bit of a pickle.

(I am getting some Sungolds still, though they ripen quite slowly, but mostly they taste pretty good, though the last bunch were kind of ripping at the stem end when I pulled them off. Does that mean I am picking them before they're ripe? They take so long I get impatient.)

Does everyone here use the Sunset zone map?

Another thing is, I plan to give away most of my seedlings anyway, since I can't handle them all, in hopes of getting to eat *more* tomatoes that way. So these could end up near the coast, and also up near Altadena.

You're also right that our weather now is just so weird, I guess I'll do a few at a time and see what happens.

But all suggestions appreciated!

    Bookmark   February 16, 2013 at 9:39PM
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Need2SeeGreen zones are useless with vegetables.
second the usual zones talked about USDA zones not sunset.

    Bookmark   February 17, 2013 at 1:01PM
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MaryMcP Zone 8b - Phx AZ

This map let's you find your zone by zip code. Like thgreatcob says, it's not perfect but I find it helpful.

Here is a link that might be useful: USDA Zone map

    Bookmark   February 17, 2013 at 2:41PM
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missingtheobvious(Blue Ridge 7a)

The USDA zones are only concerned with average annual minimum winter temperature. That doesn't tell you when it's safe to plant.

Sunset lumps me in with the rest of the Appalachians (up to southern PA) in zone 36. Winters 0 to -20? I think not! And even if it were correct, it wouldn't tell me when to plant.

Hopefully the Sunset zones are useful for folks in California. It's been too long since I lived there for me to be able to tell.

    Bookmark   February 17, 2013 at 2:53PM
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Need2SeeGreen(10 (SoCal))

Thanks, Marymcp! Looks like my USDA zone is 10. That looks like a fun website.

Thegreatcob: I didn't know that about zones and veggies. Very interesting.

Missingtheobvious: I hope you're having a good winter!

    Bookmark   February 18, 2013 at 8:00PM
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missingtheobvious(Blue Ridge 7a)

Thanks, Need2SeeGreen!

Really heavy rains every week or so. Some cold but no snow where I am (some in higher areas; I'm only 2200').

The moles are digging in my lawn, and the hairy bittercress (cute little weed which would like to take over the world) is flowering madly. I need to prune the apple trees. The violets are putting out tentative leaves; probably the pink ones are flowering -- they're evergreen, and nothing much stops them. The spring camellia flowered Thursday -- and froze Friday night; this cycle will continue for a while. It looks like this year the scillas/squill will bloom before the Jeanne d'Arc crocuses.

I will start some of the tomato seeds this week (indoors).

    Bookmark   February 19, 2013 at 1:10AM
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Need2SeeGreen(10 (SoCal))

hairy bittercress: that's a great name. I'm going to have to look that up. Weeds don't get enough respect.

    Bookmark   February 19, 2013 at 8:46PM
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Need2SeeGreen(10 (SoCal))

Hold the phone: that weed looks like the weeds I have growing on my patio right now!!!

Maybe it *is* taking over the whole world!

    Bookmark   February 19, 2013 at 8:48PM
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Need2SeeGreen(10 (SoCal))

Actually my weed might be a cousin. I'll try to post a photo soon.

    Bookmark   February 19, 2013 at 8:49PM
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I sowed amish paste tomato and austin pear seeds around 20 each( I live in N.jersey area). I bought from Not a single one germinated. I don't know the reason. I bought around 13 varieties from Other 7 varieties had more than 75% germination rate. I don't the reason for this neither I could find the reason from net. Anyone has any clue. The same germination condition for other varities applied. The germination rate of Italian Heirloom,Ildi,arkansas marvel , ammana orange was very low( 40%). ..( I bought brandywine red,yellow,aker's west,italian heirloom,ammana orange,Ildi,sprite,wisconsin 55,san marzano & arkanasa marvel).

    Bookmark   February 25, 2013 at 11:17AM
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Need2SeeGreen(10 (SoCal))

Wow, sorry to hear that! I hope you got lots of tomatoes from the plants that grew though.

I don't know what went wrong, I am a new tomato grower. (Though it sounds like maybe the seeds weren't so good. Since all the other kinds grew.)

You might want to post your question separately in the forum, you'll get more replies that way. Also, maybe contact the seller, they might have some thoughts. Maybe those kinds are just tougher to grow.

    Bookmark   February 27, 2013 at 7:10PM
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