Many traditional "old-wives' tales" and "farmer's wisdom" about planting and gardening are actually based on phenology, the study of seasonal changes in plants and animals in relation to climate and weather.
Many traditional planting rules are based on biological indicators—when certain plants leaf out or bloom, or when specific animals become active. These signals reflect cumulative temperature trends and help predict when conditions are right for planting, pruning, or harvesting.
Today on Just Grow Something we’ll do a breakdown of common gardening wisdoms across different regions, why they work, and how they can help gardeners time their planting based on natural cues. We’ll even check out some of these wisdoms from a few regions outside the U.S., namely Australia, New Zealand, and the U.K., to see how they compare. Let’s dig in!
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00:00:00
If you live in the Midwest or the northern US, you may have
00:00:03
heard an old farmer tell you to plant your corn when oak leaves
00:00:08
are the size of a squirrel's ear and that field corn should be
00:00:12
knee high by the 4th of July. If you're in the southern US,
00:00:15
you may have been told that when the Mesquite trees leaf out, the
00:00:18
last frost has passed and it's safe to plant those warm season
00:00:21
crops like tomatoes and squash. Many of these traditional old
00:00:24
wives tales or farmers wisdoms about planting and gardening are
00:00:28
actually based on phonology, that is the study of seasonal
00:00:32
changes in plants and animals in relation to climate and weather.
00:00:36
Many traditional planting rules are based on biological
00:00:40
indicators when certain plants leaf out or bloom, or when
00:00:44
specific animals become active. These signals reflect cumulative
00:00:49
temperature trends and can help predict wind conditions are
00:00:53
right for planting, pruning, or harvesting.
00:00:56
Today on Just Grow Something, we'll do a breakdown of some of
00:00:59
those common gardening wisdoms across different regions, why
00:01:02
they work, and how they can help gardeners time their planting
00:01:06
based on natural cues. We'll even check out some of the
00:01:09
wisdoms from a few regions outside the US, namely
00:01:12
Australia, New Zealand and the UK to see how they compare.
00:01:16
Let's dig in. Hey, I'm Karen and what started
00:01:19
as a small backyard garden 20 years ago turned into a lifelong
00:01:23
passion for growing food. Now as a market farmer and
00:01:26
horticulturist, I want to help you do the same.
00:01:28
On this podcast, I am your friend in the garden, teaching
00:01:31
evidence based techniques to help you grow your favorites and
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build confidence in your own garden space.
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So grab your garden journal and a cup of coffee and get ready to
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Just Grow Something. So this episode was actually by
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request from Suzanne Bennett in the Just Grow Something
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Gardening Friends Facebook group.
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So thank you Suzanne for the suggestion and other members for
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chiming in. Seconding that this would be an
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interesting episode. I can say that there are quite a
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few here that I have heard much of it having to do more with,
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like commercial row cropping, but I've picked a few from each
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region that tend to apply across the board.
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If you hear your area and I get this completely wrong, call me
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out. OK, tell me that it's not
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correct. It took a while to dig up the
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correct phenological answers for a lot of these, or to even find
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the wisdoms for some regions, so leave me a comment if I get one
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wrong or if there's one that you've heard that I don't cover
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in this episode. So we'll start with the Midwest
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and the northern US. And that first one is plant
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corn, when oak leaves are the size of a squirrel's ear.
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So this works because oak trees leaf out in response to soil
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temperature, not just air temperature.
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Corn germinates best when the soil temperatures are above
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50°F, which often coincides with the appearance of the very small
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leaves. So this avoids US planting too
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early when the cold soils could cause poor germination or seed
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rot in our corn. That second one knee high by the
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4th of July. Talking about when corn grows or
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how it's grown, essentially corn that is planted at the optimal
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time. And let's be honest, right now
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we're talking about dent corn or field corn, so the dry corn.
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So for us home growers, this might be the decorative corn or
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popcorn. OK, if we're planting that at
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the optimal time in late April to early May, then that corn
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should reach about knee high or 2 1/2 to 3 feet by the 4th of
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July. And that means it's on track for
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a full season before the frost hits.
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If it's shorter and may have planted too late, or it may have
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suffered from some poor weather or it may have lacked nutrients,
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this next one is typically from like the upper Midwest and the
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Northeast areas. And that is to wait until the
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lilacs leaf out to plant tender crops.
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So lilacs typically leaf out when consistent temperatures are
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finally there and in the garden and the frost risk has usually
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passed. So this kind of helps to figure
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out when you can plant like tomatoes and Peppers and other
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frost sensitive crops without risking whole damage.
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Now, for me, you know, in this area, that would be a little bit
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early for my tomatoes and my Peppers because I really like to
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make sure that that soil temperature has gotten really
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warm. But if all you're worried about
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is frost risk, then generally speaking, if you wait until the
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lilacs start to have their leaves, you should be OK.
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Another one is to plant potatoes when dandelions bloom.
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So this, you know, particularly in the northern US area and up
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into Canada. So dandelions bloom when soil
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temperatures reach around 50°F, and that is the ideal
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temperature for potato tuber development.
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This is going to make sure that your tubers don't rot in a cold,
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wet soil by planting them too early.
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So if we move into the southern US, we have when Mesquite trees
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leaf out, the last frost has passed.
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This is particularly in areas like Texas and the southwest.
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Mesquite trees are highly sensitive to soil and air
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temperatures and they will only leaf out when the chance of
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frost is extremely low. So this is usually used by, you
00:05:25
know, farmers and ranchers as a reliable indicator to plant warm
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season crops. So this might be tomatoes or
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squash or beans. Speaking of beans, in the
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southeastern US, it could be plant beans when pecan trees
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start to bud. So pecan trees are really slow
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to wake up and they will only bud when temperatures are
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consistently warm. So this is going to signal that
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the soil is warm enough for beans to germinate properly.
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And yes, I said pecan. Don't come at me with that pecan
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stuff, OK? It's a pecan.
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I'm just saying I'll start a war with you right now.
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Another one in the southeastern US would be when the dogwoods
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bloom, it's time to plant corn. And that means it's time to put
00:06:09
out those warm season crops. So Dogwood trees bloom when
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daytime temperatures are consistently warm.
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Usually this is around mid spring.
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And so of course, this is going to coincide with the optimal
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planting conditions for things like corn and tomatoes and
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Peppers. Then we get into like the
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northeastern US and New England, some of those are so peas when
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daffodils bloom. So daffodils bloom when soil
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temperatures reach around 45 to 50°F.
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And so that is perfect for cool season crops like your peas and
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your lettuce and your spinach. So this keeps us from planting
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them too early when the the soil is really, really cold and wet
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or waiting until it's too late and it's too warm for allowing
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those crops. Another one for like New England
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and also up in the Canada would be when Maple trees start to
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leaf out, it's safe to plant carrots and beets.
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This kind of works out in the same way.
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The timing of when maples leaf out coincides with when the soil
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has warmed up enough for root crop seeds to germinate.
00:07:12
So again, this is going to help us planting and you know, soil
00:07:16
that is too cold and avoid that slow germination from the cold
00:07:19
soil. If we get into the Pacific
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Northwest and the West Coast, when apple trees bloom, it's
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time to start those warm season crops.
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So apple blossoms open when average temperatures reach
00:07:33
around 60°F. We're talking air temperatures
00:07:36
here now. So that is signaling that is
00:07:38
warm enough for tomatoes or Peppers or squashes to go in the
00:07:41
ground. And this is going to help us
00:07:42
avoid the risk of a late frost. Another one would be a plant,
00:07:46
lettuce and greens when the forsythia blooms.
00:07:49
And you know, forsythia blooms in the early spring, usually
00:07:54
when temperatures, the air temperatures are around 40 to
00:07:57
45°F. So this would be a good time for
00:08:01
cool weather crops in more milder climates to be able to
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plant like things like lettuce and spinach and kale.
00:08:09
And then there are some things that are just kind of, you know,
00:08:13
general North American or even worldwide sort of gardening
00:08:16
wisdoms. One of those is to plant by the
00:08:20
moon cycles. Now, this has not been
00:08:23
scientifically proven, but there are a lot of farmers and
00:08:26
gardeners who believe that the gravitational pull of the moon
00:08:30
effects soil moisture. So the idea behind this is the
00:08:35
waxing moon, right? So when it's in that new to full
00:08:39
stage is best for planting above ground crops like tomatoes and
00:08:44
lettuces, the waning moon. So your full moon to the new
00:08:48
moon that is best for planting root crops like potatoes and
00:08:53
carrots. So again, this is, you know,
00:08:56
anecdotal, but what we're really looking at is like, OK, plant
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during consistent warm temperatures and proper soil
00:09:02
moisture. That's what really matters.
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However you can figure that out is great.
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Another one of these wisdoms is, you know, if you have 3
00:09:10
consecutive 50°F nights, that that means that it's safe to
00:09:15
plant warm season crops. OK, This is used really broadly
00:09:20
and it's used more in like temperate climates.
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And yes, you know, if you have your warm season crops like
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tomatoes and Peppers, they really need soil temperatures
00:09:29
that are above 55°F for really good root growth.
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So if your night time temperatures are staying at or
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above 50°F, then yeah, your soil has likely warmed enough to
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start supporting those tender plants.
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But that doesn't mean that, OK, three consecutive nights and all
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of a sudden it's safe. Because I can tell you we have
00:09:51
had three consecutive nights of 50°F weather here in West
00:09:55
Central Missouri recently, and we're actually technically in a
00:10:00
Blizzard warning right now. So seriously, some of these
00:10:04
things just don't make sense. Another one would be if the oak
00:10:10
trees are full of acorns, expect a harsh winter.
00:10:15
This one probably doesn't work. OK.
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Oak trees are going to produce varying acorn amounts based on
00:10:22
the seasonal conditions. And so I get it, high acorn
00:10:27
production, you know, thinking that you're going to predict
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winter weather with that. If you have high acorn
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production, it's usually linked to drought stress or prior
00:10:38
seasonal conditions, not necessarily predicting winter
00:10:41
weather. So this one might be fun, but I
00:10:43
don't think acorn production is a very reliable predictor of how
00:10:47
you know severe your winter is going to be.
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Planter Box direct.com. So there are a lot of
00:11:42
fascinating planting wisdoms also from other countries that
00:11:47
we here in the US might listen to.
00:11:48
So here's a few examples that I found from Australia, New
00:11:51
Zealand and the UK, along with the science behind why they
00:11:55
work. Again, this took some digging,
00:11:57
so if any of what I say is inaccurate according to where
00:12:01
you live, please tell me. And if you have some common ones
00:12:04
that I missed, please comment and let me know that too.
00:12:07
This first one was from Australia in the more temperate
00:12:11
and kind of Mediterranean climates in Australia, and it's
00:12:13
so pumpkins after the first Big Spring rain.
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So in much of Australia, particularly the southern
00:12:21
states, the first significant spring rain pretty much signals
00:12:26
the end of the really cold nights, an increase in the soil
00:12:30
moisture, which would make it perfect for like warm season
00:12:32
crops like pumpkins and squash and cucumbers.
00:12:34
So I mean, if you're planting after a good rain, this is also
00:12:37
going to help reduce transplant shock and that's going to help
00:12:40
get those plants off to a strong start.
00:12:42
So you could see how this would work.
00:12:45
This one is more from more southern Australia.
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When the waddles bloom, spring is on the way.
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Now waddle trees are an Acacia species and they bloom in the
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late winter to the early spring. So that is going to mark a
00:12:59
little bit of a seasonal shift. So a lot of gardeners going to
00:13:02
use this as a cue to start those warm season crops indoors or
00:13:07
maybe to start preparing their garden beds.
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I can get behind that one. Another one from Australia,
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never prune stone fruit trees in winter, only in summer.
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So pruning fruit trees, stone fruit trees, so we're talking
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things like Peaches and nectarines and plums in the
00:13:29
winter time in Australia is actually going to increase the
00:13:34
risk of fungal diseases, particularly Peach leaf curl and
00:13:37
die back in the very humid region.
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So if you're doing it in the summer after the leaves have
00:13:42
fully leafed out, it's going to reduce the disease risk and help
00:13:45
Direct Energy into fruit production.
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This is completely different than what we do here in the
00:13:50
Midwest. Pruning is generally best done
00:13:54
in the late winter or in the early spring.
00:13:57
So this is, you know, advice that I was not familiar with and
00:14:00
really had to kind of dig into. So if this is something that you
00:14:03
have heard and you have practiced this, you know, let me
00:14:07
know. If I'm completely wrong, let me
00:14:08
know. But this was kind of the
00:14:10
information that I that I dug up.
00:14:12
Now, if we jump over to New Zealand, we have some things
00:14:16
that I'm going to have a hard time pronouncing.
00:14:17
OK, the first one is sow peas when the cow high blooms.
00:14:22
OK, so this is the cow high tree, which is a Sephora
00:14:24
species. They generally bloom in the
00:14:27
early spring. And so this is going to signal
00:14:28
that the soil temperatures should be warm enough for pea
00:14:31
seeds to germinate. Once again, this is going to
00:14:34
avoid sowing it too early. And that wet soil, you know,
00:14:37
could absolutely cause slow germination or rotting seeds.
00:14:40
So wait until the cow high, and I'm hope that I'm pronouncing
00:14:43
that right, cow high tree. Another one for I guess both New
00:14:48
Zealand and Australia would be to plant garlic on the shortest
00:14:51
day, harvest on the longest day. That works here also, although
00:14:57
we kind of tend to, you know, shift that a little bit based on
00:15:00
our frosts. So if you're in the southern
00:15:03
hemisphere, the shortest day of the year is usually around June
00:15:06
21st. And that marks the ideal time to
00:15:09
plant garlic because you need that cold exposure to form
00:15:13
proper bulbs. And then you're going to want to
00:15:15
harvest on the longest day, which is around December 21st.
00:15:18
And that aligns usually with the garlic maturing as the days are
00:15:21
getting hotter and drier. And that helps to cure the bulbs
00:15:23
properly for storage. The exact same thing works here
00:15:27
in the Northern hemisphere, but we're just swapping those dates.
00:15:30
So we're planting around December 21st and we're
00:15:33
harvesting around June 21st. Now, depending on where you are,
00:15:39
and this could be both Northern and Southern hemisphere, it's
00:15:42
going to depend on your soil conditions at the time that the
00:15:47
longest day of the year comes around.
00:15:49
So often times you might be, you know, December 21st, your ground
00:15:53
might be frozen solid. So if you have to plant it
00:15:55
earlier than that, then there's no harm, no foul on that.
00:15:58
So you should be planting around the time that it works best for
00:16:03
your soil conditions. So that wisdom of plant on the
00:16:07
shortest day and harvest on the longest day, it makes sense
00:16:11
until it doesn't, right? So the next one is from coastal
00:16:15
New Zealand, and I'm really hoping that I'm going to
00:16:18
pronounce this correctly. If Pahu.
00:16:21
Oh, gosh. OK, let me do this again.
00:16:24
Pahu tukawa. I really hope I'm doing this
00:16:28
right. If pahu tukawa flowers bloom
00:16:30
early, expect a hot, dry suburb. All the New Zealanders are
00:16:35
laughing at me right now. The Bahuka Pahu Pahu Tukawa
00:16:41
tree, OK, This is the Metro Sediris Excelsior.
00:16:43
That's the Latin name for it. It is known as New Zealand's
00:16:47
Christmas tree. And so it flowers in the early
00:16:49
summer. And so some people believe that
00:16:51
if it's you've got an early bloom, so late spring instead of
00:16:55
the early summer, then that means that warmer conditions are
00:16:59
coming sooner, which could indicate a longer, drier summer.
00:17:02
So this is classic phonology. You know, the plant is
00:17:05
responding to climatic cues, and that also may impact your
00:17:09
seasonal weather. So, OK, somebody from New
00:17:12
Zealand, please tell me if I pronounce that properly.
00:17:14
That was a heck of a pohoutukawa.
00:17:17
I think that's what it is. All right.
00:17:19
I'm usually pretty good at things.
00:17:21
And then if we move over to the UK, we look at Great Britain or
00:17:25
UK and Ireland plant potatoes when the black thorn blossoms.
00:17:30
So black thorn is a Prunus spinosa.
00:17:34
They flower in the early to mid spring, which is around March to
00:17:37
April. This is going to coincide with
00:17:39
the time when soil temperatures generally reach around 45°F or 7
00:17:43
Celsius and that is the minimum needed for potatoes to sprout.
00:17:47
So this is a good sign. It helps us to avoid the
00:17:49
planting too early. We don't want those tubers to
00:17:51
rot in the cold wet soil. So we wait until the black
00:17:53
foreign flowers. Perfect.
00:17:56
Another one would be so carrots when the ash trees bud, So ash
00:18:01
trees bud a little bit later than a lot of other trees,
00:18:04
usually not until the spring temperatures like to start to
00:18:07
stabilize. So that generally means that the
00:18:10
soil is warm enough for carrot seeds to germinate quickly.
00:18:15
We all know carrots are Divas. They can take like 3 weeks to to
00:18:19
to sprout sometimes. So if we can get them to sprout
00:18:22
faster, this is going to reduce the risk of slow, weak
00:18:26
germination in a soil that is maybe too cold.
00:18:29
And if that happens, then we, you know, we get forked or
00:18:32
stunted carrots. So if we wait until the ash
00:18:35
trees have budded act, then it should be warm enough for those
00:18:38
carrot seeds to germinate quickly.
00:18:40
Another one involving ash is if oak before ash, we're in for a
00:18:45
splash. If ash before oak, we're in for
00:18:49
a soak. So this is basically suggesting
00:18:53
that if the oak trees leaf out before the ash trees, then it
00:18:58
will be a drier summer. But if the ash trees leaf out
00:19:01
first, then we're expecting a wet summer.
00:19:04
So, I mean, this works because A, we already talked about the
00:19:08
ash trees budding out later than many of the other trees, but oak
00:19:12
trees tend to respond to temperature, while ash trees
00:19:17
tend to be more sensitive to soil moisture.
00:19:21
So if you have a warm, dry spring, that is going to
00:19:25
encourage the oaks to leaf out early.
00:19:28
But if you have a wealth spring, that's going to slow those oaks
00:19:31
down and it's going to let those ash trees emerge first.
00:19:34
I mean, this isn't perfect, but it is a good example of how
00:19:37
trees respond to climatic changes.
00:19:39
So this one's maybe 5050. I don't know about this one.
00:19:42
And then finally we have plant beans when the Hawthorne blooms.
00:19:47
So Hawthorne is also known as Mayflower and it generally
00:19:50
blooms in wait for it may, right.
00:19:53
So this is signaling that the conditions are warm enough for
00:19:56
beans. Beans need soil temperatures
00:19:58
that are generally above 50°F or 10 Celsius, and that usually
00:20:02
aligns with Hawthorne flowering. OK, so no matter where you are
00:20:09
in the world, there is going to be some local folklore about how
00:20:13
and when to plant certain things based on the activities of other
00:20:17
plants or even animals. We didn't even get into the
00:20:19
whole animal Kingdom thing, right?
00:20:21
This wisdom is often passed down through generations.
00:20:24
The timing of these things is not based on a calendar, so even
00:20:29
as our climate shifts warmer or cooler in certain areas, these
00:20:34
indicators are going to remain the same.
00:20:37
So modern weather forecasts can help us to plan, but nature's
00:20:43
signals are going to actually remain.
00:20:44
One of the best guides for gardeners.
00:20:48
By using phonology, which is watching the timing of the plant
00:20:51
in the animal activity, we can actually get region specific
00:20:57
planting cues based on actual weather patterns rather than
00:21:01
dates on a calendar or forecasts from weather gurus.
00:21:04
We just have to be able to decipher which is actually,
00:21:07
actually accurate and which isn't.
00:21:09
So the next time you see oak leaves emerging or forsythia
00:21:14
blooming, take note. It might just be time to start
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planting. Thanks again to Suzanne for
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suggesting this topic. If you have a topic you'd like
00:21:22
me to cover, reach out to me through socials or in the
00:21:24
comments of an episode, or through e-mail from my website,
00:21:28
justgrowsomething.com. I would love to hear it.
00:21:31
Until next time, my gardening friends, keep on cultivating
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that dream garden, and we'll talk again soon.