How to Grow: Pea plant - Vegetable of the Month

Pea plant stats/requirements at a glance

Ease of Raising:	2/5	- Biweekly check-ups
Water:	2-5	- Twice a week
Sun:	4/5	- Full sun, shade tolerant
Training:	4/5	- Moderate, train up a trellis
Fertilise/Feeding:	4/5	- Fortnightly, half strength fertiliser
Time to Harvest:	4/5	- 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

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!

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 17^th 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 16^th 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.

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 20^oC.

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.

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.

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. 

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 4-24^oC (40-75^oF).

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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