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Date of Last Frost

Posted by truckaduck 5 (My Page) on
Fri, Jan 25, 13 at 21:00

Hello, I am in Denver. I have many questions! When instructions say to plant "after the last frost", when is this? Does it matter that it may snow after the last frost? Is there anything that can be planted directly outside BEFORE the last frost? Thank you!


Follow-Up Postings:

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RE: Date of Last Frost

When instructions say to plant "after the last frost", when is this?

Hello, depending exactly where you are in Denver, some time around the first or second week of May.

Does it matter that it may snow after the last frost?

Oh, yes.

Is there anything that can be planted directly outside BEFORE the last frost?

If you are speaking of seeds, yes. Usually the package will say 'sow outside as soon as the soil can be worked' or some such.


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RE: Date of Last Frost

I've lived in the southwest suburbs of Denver for about 28 years. I'm not an avid gardener, but I do plant annuals, perennials, and herbs every year. I always use Mother's Day as my marker for planting, although we have had snows in late May and even early June a few times since we moved here. I keep tarps handy in case there's a snow or freeze after the planting is done. The hardest part is waiting for Mother's Day when there's a mild spring and all my neighbors are planting in late April/early May. Good luck, truckaduck!


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RE: Date of Last Frost

  • Posted by skybird z5, Denver, CO (My Page) on
    Mon, Jan 28, 13 at 14:51

Hi Truck!

It depends on what it is you're wanting to plant!

If it's "warm season" veggies, they can't take frost at all and would need to be well protected if we got down around or below freezing after they were in the ground. But "warm season" crops don't do well in cold soil and conditions, so it doesn't really help to plant them out "too soon" anyway!

"Cool season" veggies (peas, spinach, cole crops, radishes, +) can take frosts (and snow) IF they're well hardened off before they're put into the ground.

Things like hardy perennials & herbs (and trees and bushes) can also take frost and snow as long as they've been well hardened off before planting. If any of those things are purchased locally at a garden center where they've been grown outside, they should already be hardened off. But if you pick up something at a big box store or somewhere else where their plants are shipped in from another state (often California or somewhere on the West Coast), they will NOT be hardened off and you'd need to do it yourself in order to be able to safely plant them out.

So it just depends on what you're thinking of! Hardy stuff (that does NOT include the "Hardy Boy" brand, which is just a marketing name!) can definitely be planted out when there's still "danger of frost" as long as it's been adequately acclimated.

Welcome to RMG,
Skybird


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RE: Date of Last Frost

Thanks everybody! All of this input is helpful! I will indeed have a tough time waiting for Mother's Day... I'm pretty excited. But I think I'll do some snow peas and lettuce from seed, earlier than that, per your advice. Woohoo! Thank you again, and I'm sure I'll be back with more questions.


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RE: Date of Last Frost

Going by good ol' folklore, I plant peas and favas on Good Friday. Some people also plant potatoes then as well. You can plant beets, chard, and spinach early as well.

But if you plant chard and spinach in the fall (late August here), and let 'em send down tap roots and over-winter, you get much better results.


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RE: Date of Last Frost

Thank you.... we were going to plant beets, potatoes, and spinach as well. Good to know we can do it early! As for planting spinach in the fall, do you refrain from harvesting that season to allow them to over-winter in a complete state?


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RE: Date of Last Frost

This might be helpful! It's a chart from the Tom Clothier site showing optimum soil temperature for various veggies.

Example: You could plant parsnips when the soil was 32 degrees and you'd get 82% germination--but it would take 172 days for them to germinate!!! If you plant them at the optimum temperature, 68 degrees, you'd get 89% germination--in 14 days! But you could also plant them 10 degrees cooler at 59 degrees and still get 85% germination in just 19 days.

So this gives you an idea of which ones can be planted earliest and approximately how warm the soil needs to be to get the best results.

As for me, I have a LONG way to go before I'm ready to plant ANYTHING! But, since I always get them in too late, I'm planning to start some lettuce and spinach in big pots this year while it's still cold enough out to be sure I actually get something to eat!

Happy dreaming,
Skybird

P.S. The Tom Clothier site has GREAT germination info on perennials and annuals--and lots of other good stuff too!

Here is a link that might be useful: Germination Temperature


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RE: Date of Last Frost

As for planting spinach in the fall, do you refrain from harvesting that season to allow them to over-winter in a complete state?

The times I've done it, I've been so swamped with other stuff that I didn't pick any leaves in the fall. They manage to stay green most the winter, getting a bit crispy on the edges. I just mulched the bed and kept it moist, gave it a shot of high N fertilizer in March, and was picking gobs of fresh spinach in April.

If you're anywhere near deer, they like spinach too. And they'll clean you out overnight.


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RE: Date of Last Frost

David we are going to try this, definitely. Thanks so much. And Skybird, thank you for the link. This is way more scientific than anything I've attempted in the past and I want to increase my knowledge!


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RE: Date of Last Frost

These are good sources for frost data data.

http://www.victoryseeds.com/frost/

http://cdo.ncdc.noaa.gov/cgi-bin/climatenormals/climatenormals.pl?directive=prod_select2&prodtype=CLIM2001&subrnum to Freeze/Frost Data from the U.S. Climate Normals

http://www.wrcc.dri.edu/htmlfiles/co/cominthr.html


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RE: Date of Last Frost

Thank you Magnolia!


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RE: Date of Last Frost

A while ago someone posted a link to a really handy gardening calendar. If you plug in your first and last frost dates it will tell you what to plant and when, even when to start seeds indoors. With this link and the link above (NOAA) you can tell what you should do when.

I have say that I have always used the "old wives tale" that flwrs_n_co mentioned: Mother's Day!

Then link below also gives first/last frost dates:

http://www.climate-charts.com/States/Colorado.html

Here is a link that might be useful: GrowGuide Seed Starting Planner


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