Depends entirely on where in the world you are, and what you are doing. Ideally you should not plant pepper and tomato transplants out when temps get into 30-40s, and should have waited.

Do you mean you planted seed ? Too early for tomatoes and peppers where I live. Both of those are warm weather plants, and can't be transplanted to the garden until mid-May, or later.

As noted, it depends where you are. Tomatoes will survive 30s and 40s, but may be stunted. More importantly, if in a cold climate, such that the soil is still very cold, tomatoes will not do well. I try to plant my tomatoes as early as possible, because for me it's a race to get fruit before it gets too hot. I can wait to plant out until just after the last frost, because in my climate, my soil is not very cold.

I'll be planting out in the last week of February.

I agree, it depends :-) The standard recommendation is you start seeds of tomatoes, peppers and other hot season crops indoors 6-8 weeks before the listed last frost date for your area with the intention of planting them out about 2 weeks later. If planted now, that implies you should be ready to plant these starts out in mid April.

However, there are other factors involved as well. Given the above recommendations, my last frost date is approximately the end of March, so starting the seeds now would seem reasonable. However, garden soil here is slow to warm up and nighttime temperatures are slow to move above 50F, so planting out these crops is not advised until late May or early June. Starting the seeds now in my climate is a waste of time and effort as they will be potbound and excessively leggy waiting until it is safe to plant them out.

Just realized I forgot the AZ tag lol. I'm in zone 9b and our last frost date is usually the first week of Feb, but have had some cooler weather recently. I also should have mentioned they're transplants in wicking buckets that I made (past home had raised beds, but no garden space here). Were hitting low to mid 70s during the day, but low to upper 40s at night - given they're buckets, I can probably bring them in each night for the next few weeks?

That should work. I've been shuttling my plants in and out for the last couple of weeks (60s during the day, upper 30s at night). They really have to be planted this week, so I have my cloches and blankets on standby...

Unless you're in the mountains in Arizona, your soil temp should be 60F-ish. That's fine. If the extended forecast is a good one, I'd say you're pretty much ready to go. I thought I might be planting out this week, but then a fierce arctic front hit us. Last night temp was 6F, lowest in thirty years, and there are several inches of snow on the ground. REALLY unusual. Looks like I'll wait another week or two, and plant out some slightly overgrown tomatoes.

Just remember that containers will cool down faster at night than plants in the ground. On the plus side in Arizona you probably get clear warm sunlight every day, and you don't have to worry much about cold wet soil.

I'm trying to figure out the perfect time to start tomatoes and peppers this year. I'm thinking I'm going to plant peppers earlier than usual, so I can top them and get bushier plants. But tomatoes grow faster and leggier, so I don't want to sow those too soon.

I figured out my frost free date looks like about May 7th. I don't want to have to pot up tomatoes to more than one more size from a 6 pack. Is that reasonable? I also have some outdoor protector to put around the plants when I put them out. I'd warm up the raised bed ahead of time with black plastic, and you have to harden them off if you're growing under lights, right? So any idea how many weeks I should back up from the frost free date for the tomatoes?

Prairiemoon, do you have a heating mat (or a nice warm spot) to start your plants? With a heating mat, it takes a week to get germination and the plants take off quickly. But at room temperature, it's a big unknown. Before I got my mat, I had to wait about 3 weeks, and the plants were still sluggish. So it can make a difference of about a month.

Yes, JoJo - I have a light set up - a nice circulating fan and a heating mat. I haven't started under lights in a few years, so I forgot about the heating mat. That does make a difference, thanks for the reminder. Great tip, thanks! I didn't realize it made that much of a difference.

Great! It made a difference for me in my old, drafty colonial in Maryland...

Pretty drafty around here too and a little colder in New England to boot! [g]

Coincidentally, I planted my tomatoes, peppers, eggplant and herbs earlier today. I started them on Christmas Eve with a heating mat (only for germination) and lights. I started bringing them out during the day on Feb. 8. So the whole process took about 8 weeks.

So 8 weeks from start to finish for peppers and tomatoes and they're already hardened off? I imagine your weather for the past 8 weeks has been pretty warm? Nothing like NE spring weather I bet. [g] How large a plant do you have after 8 weeks?

The size of your seedlings depends largely on the temperature. If you grow them at 55F, they'll grow slow. If at 80F, they'll grow twice as fast. I would have planted my tomatoes out this week, but the arctic cold front prevented that. I was growing them at 70F (after three weeks they are 3 inches tall), but I've now dropped the temp down to 55F to slow them down a bit. I suppose that's also hardening. They'll get planted out after four weeks. Peppers are slower. At 70F, mine are two inches tall after four weeks of 70F. They'll go out in two more weeks.

JoJo is exactly right. In our climate, it's a race. Very important to get tomatoes started early, because when the heat comes on, you're done.

Thanks Dan - I start seedlings in the basement, but it's warm there, probably 60 - 70 degrees. I am going to have to check with a thermometer. We set the thermostat to 64 for the night.

That makes sense that they grow faster in warmer temperatures. So if you see you are going to be able to get them out there earlier, I guess you could speed up the growth by turning up the heat? But then wouldn't that make it harder to harden them off well?

How do you drop the temperature to 55 degrees? I don't have a spot in my house that is that cool.

So you only grow your tomato seedlings for 4 weeks once they germinate before you plant them out? But you grow the peppers for 6 weeks, right?

See, I admire anyone who gardens in such a warm climate. Once the heat comes, I would be done, never mind the plants! [g]

I do my seedlings under lights in a converted garage. So the temperature there fluctuates with the outside temp. When the outside temp is 10F, the temperature inside that converted garage is barely above freezing. BUT, I have the plants under fluorescent lights, and not LEDs. The advantage of that is that fluorescents produce some heat. LEDs don't. So I regulate the temperature by pulling a blanket over the setup. Pull over more for warmer, less for cooler. It's not an automatic thermostat, but if you check on them once or twice a day it works great. Long ago I was intrigued about going to LEDs, but not so anymore. If I did, I'd need heat mats.

I grow them all in 9oz paper cups, so I shoot for 4 inches tall at plantout. At 70F, that's four to five weeks for tomatoes. Takes a bit longer for peppers. I guess in principle you could speed them all up more by going warmer. For tomatoes and peppers, the optimum temperature for seedlings is actually more like 85F.

Yes, down here we are blessed to have a very long growing season. But it doesn't work that way for tomatoes! Plant out in March, and you're all done in July. Some people try for a second season in the fall, but survival of outdoor seedlings when the temperature is over 100F is chancy, and keeping the mature plants going in those temps requires some effort, if fungus doesn't get them first.

It sounds like a nice set up Dan. 9oz cups are an idea. I want to time mine, so I don't have to transplant to a larger size more than once at most. I have started in cell packs then graduate to 4" pots. I know some people grow their tomatoes huge before they go out, but they grow so fast once they get in the ground, if it's warm enough, I'd just rather plant them out sooner. I have some pop up protectors to increase the temperatures for a couple of weeks too.

I don't have room for too many tomatoes, but I have more room for peppers, so I start more of those. I do plant those out later than tomatoes here because even if the day temperatures are warm enough sometimes spring weather overnight is on the cooler side.

I just want to avoid starting too early. I did that a couple of times and did not enjoy holding them if the weather stayed cool and then I had to transplant them all again.

I think I'm going to start mine in larger containers than the cell packs this year. Thanks. Good luck!

In growing tomatoes and peppers, the soil temperatures have to partly determine the strategy. My soil temps hardly get below 60F, so after last frost, blam! they're in. If your soil temps are a lot lower, your tomatoes and peppers won't like being in the ground. I think soil temps need to be at least 55F for them to be happy. In the PNW, where I used to live, the soil wasn't warm enough until at least a month after last frost. In MA, this link should be helpful ...

http://newa.cornell.edu/index.php?page=soil-temperature-map

Yes, right idea. I have a soil thermometer. And some raised beds that I'm not sure I will plant peppers in or not. I'll also be placing black plastic where they are going to speed things up. Yes, no sense of them going out and just sitting there. Thanks for the link. I guess it's about 28 degrees out there now. lol I'll have to keep checking this site.

starting seeds indoors and planting out are two different issues. I would like to Comment on plant out.

TOMATOES are cold Hardy and can survived lows above frost without

Protecting. But it would be much safer over 42f overnight.

PEPPERS are cold sensitive. I would wait longer until maybe lows are in 50s.

Another issue is HARDENING OFF. You have to introduce your seedlings to the elements(cold. sun, winds) gradually say for 7 to 10 days.

Google and search on that for details.