Pea
plant stats/requirements at a glance
Ease of
Raising:
|
2/5
|
- Biweekly check-ups
|
Water:
|
2-5
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- Twice a week
|
Sun:
|
4/5
|
- Full sun, shade tolerant
|
Training:
|
4/5
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- Moderate, train up a trellis
|
Fertilise/Feeding:
|
4/5
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- Fortnightly, half strength fertiliser
|
Time to
Harvest:
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4/5
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- A long time, 3-4 months
|
Frost
Hardiness:
|
3/4
|
- Mildly hardy, can’t cope with severe frost
|
Uses
|
Culinary
|
|
Most
Problematic Nemesis:
|
Heat, mildew
|
|
Container
Plant:
|
Yes
|
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| Pisum savitum Flora von Deutschland Österreich und der Schweiz 1885 |
Quick
intro
I’ve never been fond of peas, especially
those frozen things, except ham-and-pea-soup! Fresh snap peas direct from the
plant, however, had me converted to a pea lover. They are especially convenient
when it comes to grab and eat veg for lunches or dinners. Unfortunately peas
can only be grown in winter in SA (especially the hot-summer areas), because
the heat of the SA sun, peas grow poorly in summer and fail to crop. Peas can
be used in any form, whole, split, ground into flour and dried. They feature in
many different recipes; such as soups, puddings and convenience-foods (canned
or frozen). I also know that the British are especially taken with mushy peas,
bangers and mash!
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| Snap Pea flowers Pisum savitum var macrocarpon |
History
Peas were likely domesticated in
south-western Asia and the eastern Mediterranean during 8000BC. The cultivation
of peas spread eastwards to India and China throughout 1000AD. In the 17th
century, peas were often grown in English gardens by the Romans and dried peas
were very popular in ancient Europe. The love of green peas (specifically mange
tout in France) only happened in the 16th century.
Science
Stuff
The humble garden pea (AKA English, Green,
Common) is known as Pisum sativum.
Other pea types such as those with edible pods, snap, sugar or snows are a
subtype known as Pisum sativum var. macrocarpon. Peas and beans belong to
the same family of leguminous plant, Fabaceae. They are nitrogen-fixing; they
convert atmospheric nitrogen to bio-available nitrogen in the soil by symbiotic
bacteria contained in their root nodules and thus they add nutrient to the
soil. Due to this characteristic peas are high in proteins (of which nitrogen
is a main component), 23% protein, 1% fat and 59% carbohydrates. Another
advantage of peas is that they contain no toxic parts, many other vegetables
might have a poisonous component (such as the fruits of potatoes).
All flowering plants will produce fruits,
and are thus, technically botanical fruits. The pea is known as a dry-fruit, a
dehiscent legume. The development of the pea pod leads to the classification of
two main types:
Shelling: These have though pods and seeds
develop rapidly within the pod.
Snap/snow/mange tout: Also known as eat-all
peas have crisp/tender pods with delayed seed developed and are eaten with the
pod on.
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| Snap Pea cropping Pisum savitum var macrocarpon |
Several intermediate varieties have been
bred with normal seed development rates, but have tender pods suitable for
eating. The Asparagus peas have four winged brackets and taste asparagus-like.
Asparagus peas are legumes, but belong to a different genus, Lotus tetragonolobus.
Growing
Peas
Cool-climate growers will likely be able to
grow peas during their summer months or even right through the year.
Warm-climate countries, such as South Africa, will have to grow their peas as a
seasonal winter crop. I will give growing information on the snap peas (edible
podded) varieties.
It is preferable to sow peas directly into
the soil of the garden plot, alternatively you can buy seedling or start them
up indoors (where it is cooler) in order to plant outside once the average day
temperatures drop to below 20oC.
The pea plants germinate fairly quickly,
but are slow to mature and produce pods (hence another advantage of starting
early). Peas are generally self-sufficient, but they require stakes or trellises
for their tendrils to grasp and support the plant. You can feed them, I usually
fertilise once every two weeks with half-strength liquid feed.
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| Snap Pea tendril Pisum savitum var macrocarpon |
Other
Pea plant Tips
Peas are very productive and the more you
pick the more they produce.
Don’t leave pods on the plant for too long
as they become tough and might slow production of the plant. If you want to
harvest seed, let some pods dry towards the end of the season.
The peas can be pruned a bit to have a more
‘open’ branching structure, so that branches don’t cross or pods aren’t
produced on the inside of the bush where they are difficult to spot and get to.
Sometimes pea seeds suffer from rot before
germinating. Therefore some people plant pea seeds in moist soil, water it once
and don’t water it again until the shoots have emerged.
Be careful of not perpetuating
legume-disease by planting your peas/beans and green manures in the same bed
season after season, try to rotate the crops with non-legumes or interplant
with non-legumes.
Remove pea pods with scissors as they can
be quite stubborn and yanking might damage the parent plant.
Peas are fairly prone to downy mildew,
especially in humid conditions or after long periods of rain. See my Pest
control post for a downy mildew spray (duals for cucurbits and carrots as
well).
Harvesting
and Storing
Pea pods can be harvested as soon as the
flower drops and the pea-pods develop. Small pods are very sweet and tender,
whereas larger ones with have a good crisp bite to them.
Peas, in my experience, don’t keep well.
They can probably do three days to a week in the fridge, but are best prepared
or eaten right after harvest. I think that because these are tender-podded
varieties they don’t freeze well either, I assume that the peas with though
pods can be emptied and the individual peas can be frozen with much more
success.
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| Snap Pea Pod Harvest Pisum savitum var macrocarpon |
You can pickle peas, but I don’t like
pickles, so I haven’t tried that. Therefore, I enjoy my pea bounty once a year
during the winter months J
Propagation
I love the term for pea flowers: “Papillonaceous”.
Papillon, it French for butterfly, which is what pea flowers look-like. These
butterfly-flowers are self-pollinated, but may be visited by the bees when the
other winter-flowers are scarce. Due to this peas outcross rarely, but if you
want ‘pure’ stocks, then separate by 15 meters (50 feet) to isolate by
distance.
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| Snap Pea flowers Pisum savitum var macrocarpon |
Peas are grown as annuals and their seeds
can be saved for up to three years. Dry, brown pods that rattle are mature and
ready to harvest. Leave them for another week to two weeks before shelling and
storage. [No tedious fermentation required, Yay!]. Store in glass, air-tight
jars to optimise shelf life. These seeds are then sowed once the soil has
reached 4-24oC (40-75oF).
Something
interesting – Mendel’s Pea Garden
Gregor Johann Mendel was an Austrian monk
(Brno, Czechoslovakia). He is the founding father of genetics. He studied the
heredity of discrete, non-overlapping characters that are transferred from the
parent to the offspring, more commonly referred to today as genes. He studied
the garden pea as he could identify seven heredity characteristics and
performed several cross-breeding experiments on these. In order to study the
inheritance of these traits Mendel cultivated over 29 000 pea plants over
a period of seven years and meticulously recorded what he observed with
different crossings and several generations of certain crosses.
His studies resulted in the basic genetic
principles (Mendel’s Law of Inheritance) now taught to students who study Life
Sciences. These laws have two important fundamentals:
The
Law of Segregation: This involves that
characteristics are governed by two separate entities (genes). These genes can
have different variants, known as alleles. The two genes split during
reproduction and only one is transferred to the offspring from each parent.
For example – Let us look at the
characteristic of plant height. One plant is tall, the other is short. These
two plants are the parents (P generation), which we cross and obtain offspring
(F1 generation). We observe that all offspring of this cross are tall. Curious,
you say? Well, let us observe what happens when you cross two F1 with one
another (Tall x Tall). Now we observe that 75% of the offspring are tall, whereas
25% of the offspring are short (this is the F2 generation).
This is an example of a simple genetic
inheritance, where one trait is dominant (and will always be expressed
regardless of the status of the other gene) and the other is recessive. Here, the
tall trait is dominant and the short is recessive. Let me give them symbols and
elaborate the crosses with those: Watch what happens…
Tall plants: T, dominant symbol
Short plants: t, recessive symbol
P1 Tall plant = TT (remember there are 2
genes) & P1 Short = tt
These traits will split during gamete
formation, so each gamete will have either one T or t and with 4 gametes we can
illustrate in a table (known as a Punnett square, much like a plant seedling
punnet LOL!). Gametes are marked in yellow, offspring or zygotes marked in
green.
Gametes
|
T
|
T
|
t
|
Tt
|
Tt
|
t
|
Tt
|
Tt
|
See what happens: all the offspring get one
T and one t. This means that the T trait ‘overrules’ the t trait and all
offspring (F1) are tall! Now we do the F1 x F1
Gametes
|
T
|
t
|
T
|
TT
|
Tt
|
t
|
Tt
|
tt
|
Hah! Those sneaky pea plants! Now we can
see why our F2 are 75% (3 out of 4) tall and 25% (1 of 4) short.
But what about two traits (for instance
plant height and pea colour) were analysed together?... this leads to Mendel’s
second law-
 |
| Snap Pea Winter Plot Pisum savitum var macrocarpon |
The
Law of Independent Assortment: If two
characteristics are analysed at once, they would act independent from one
another (the one doesn’t affect or determine the outcome of the other). I’ll
quickly illustrate this as I did above, but with two traits; plant height and
pea colour.
Plant height: Tall gene, T, dominant &
Short gene, t, recessive
Pea colour: Yellow gene, Y, dominant &
Green gene, y, recessive
Parental generation (P1) are Tall Yellow
(TTYY) plants crossed with Short Green plants (ttyy) : F1 would be:
Gametes
|
TY
|
TY
|
ty
|
TtYy
|
TtYy
|
ty
|
TtYy
|
TtYy
|
So all offspring would be Tall with Yellow
peas (TtYy)! Now let’s do F1 x F1 (TtYy x TtYy); we need to expand the table to
allow for all combinations:
Gametes
|
TY
|
Ty
|
tY
|
ty
|
TY
|
TTYY
|
TTYy
|
TtYY
|
TtYy
|
Ty
|
TTYy
|
TTyy
|
TTYy
|
Ttyy
|
tY
|
TtYY
|
TyYy
|
ttYY
|
ttYy
|
ty
|
TtYy
|
Ttyy
|
ttYy
|
ttyy
|
Whoa! This makes things seem more
complicated, but it really isn’t. Each still goes by the 75:25 rule (or 3:1
rule) as above, it is just expanded by adding two traits and becomes a 9:3:3:1,
such that:
9/16 plants are Tall with Yellow peas
3/16 plants are Tall with Green peas
3/16 plants are Short with Yellow peas
1/16 plants are Short with Green peas
This is an example of very basic genetic
inheritance, and many traits do go by these rules (such as hair colour and eye
colour in humans, but with more than two variants). You would also notice that
the recessive gene is always in the minority, mostly due to them being
detrimental (but not always!) and many diseases are caused by recessive genes
(were two recessive genes are need to be present to cause the disease)…
Anyways, I hope you enjoyed my quick Genetics 101, so let’s get back to growing
peas instead of crossing them J…
My Pea
plants
I only have good ol’ snap peas: Starke
Ayres Green Feast variety
 |
| Snap Pea Pisum savitum var macrocarpon |
So when you grow your pea plants, check to
see which of the seven characteristics they have according to Mendel’s
observations!
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