Sweet Peas (Lathyrus odoratus)

Summer Sweet Peas

For us, January is the time to start sowing Sweet Peas.  They are quintessential cottage garden plants with their delicate frilly petals and delicious scent.  In our view a Sweet Pea is not worth growing if it does not have a good scent.

As a flower Sweet Peas evoke such memories for both us and our customers.  They remind me so much of visiting my Nan on the Kent coast where the blooms would be picked fresh from the garden, simply arranged in a vase and the scent allowed to permeate throughout the rooms of the house.  Equally we have found that our customers have also loved them over the years.  When we used to run a Country Market stall simple bunches of Sweet Peas would always be the first to go.

Sowing and growing sweet peas

There seems to be a lot of mystique around sowing sweet peas but we have always found them very easy to grow and needing no specialist equipment or seed treatment.  Although in the past we have soaked the seed overnight before sowing we have not found this necessary to get good germination.  Roger Parsons ( www.rpsweetpeas.com ) indicates that soaking or chipping the seed may in fact reduce germination.

We certainly have good success with the following approach:

  • Sow 3 or 4 seeds in January in standard 9cm pots of a mix of multi-purpose compost and perlite.
  • Water well and place on the kitchen window sill (this is usually around a constant 18°C-20°C).  Do not water again until the seedlings start to emerge.
  • You will typically see the first seedlings show themselves in about 7-14 days.
  • Once the seedlings have emerged we move them out into a cold, unheated greenhouse.  They are best grown on hard in plenty of light so that they do not get leggy.  If the temperature drops to below -5°C they may need some protection.
  • We keep the seedlings up high on the greenhouse staging so that there is less risk of mice and other rodents getting to them.
  • Once the plants have reached four leaves, pinch out the tops of all the plants so that they bush out.
  • In around mid-March, we harden off for a couple of weeks before planting out into the garden.  We have grown them up canes in the past but this requires a lot of attention to ensure the plants are tied in effectively.  More recently we have found that standard pea and bean netting works particularly well as long as you buy a decent quality that can be used again and again over a number of years.
  • You should create a deep well dug planting trench incorporating lots of well-rotted organic matter into the soil both to hold the moisture and feed the hungry plants through the season.
  • Plant out the whole pot of 3 or 4 plants together without disturbing the roots and water in well.  Each pot should be planted around 12 inches apart and the tendrils gently encouraged to take a grip of the netting.
  • The final stage for us (if we don’t want to have wasted all our hard work) it to run chicken wire around the base of the row to keep the rabbits at bay.

All you need to do now is stand back and watch them grow making sure that you keep them regularly watered and fed with a liquid feed every couple of weeks once they are flowering.   As soon as they start to flower pick them regularly (probably every day).  The more you pick the more flowers you will get.

It is possible to succession sow into March/April if you want to extend the flowering season.

Sweet Peas ready to pick
Sweet Peas growing vigorously and ready for picking in the Honey Pot Flowers garden

Varieties to grow

There are so many varieties to choose from that it is often difficult to know where to start if you have not grown them before.  Actually half the fun is experimenting with new varieties each year to see what you like.  For us, although colour and a long stem length are important, a sweet pea is not worth growing if it does not have a decent scent.

Roger Parsons offers a wide range and groups them into the following types:

Spencer & Summer Multiflora varieties  – the best types for exhibition and for cutting for the house.

Old Fashioned, Grandiflora & Semi-grandiflora varieties  – the best types for scent and garden decoration.

Early-flowering varieties –  for Winter and Spring flowers, including Early Multiflora type for cut flower production

Dwarf and Semi-dwarf varieties – for garden decoration when shorter plants are required

Very helpfully an indication of scent strength is also offered against each variety.

Varieties that we grew in 2017

  • Albutt blue (Pale whitish blue – Semi Grandiflora)
  • Cathy (Creamy white – Semi Grandiflora)
  • CCC (White  – Modern Grandiflora)
  • Jilly (Creamy white – Spencer)
  • John Gray (Pale pink  – Spencer)
  • Judith Wilkinson (Bold bright pink – Spencer)
  • Yvette Ann (Salmon pink – Spencer)
  • Just Julia (Mid blue – Spencer)
  • Naomi Nazareth (Pale blue – Spencer)
  • Matuccana (Dark red and blue – Modern Grandiflora)
  • Adorabel (Lavender/mauve – Modern Grandiflora)
  • Solitude (Lavender – Spencer)
  • Almost Black (Dark maroon – Modern Grandiflora)

Rather than buy costly new seed every year we allowed some plants to go to seed.  This was collected and stored in paper envelopes over the winter and we will be sowing these in the next few days.

Pale blue sweet peas with lime green Alchemilla
Pale blue sweet peas with lime green Alchemilla

Cutting, conditioning and arranging with Sweet Peas

It is fair to say that the vase life of sweet peas is rather shorter than many cottage garden flowers.  Having said that you will have so many to cut that you can easily provide the house with a constant supply of fresh, fragrant blooms for day after day throughout the summer.

For the longest vase life pick early in the morning when only the first bud on the flower is open.  Be careful not to bruise the delicate blooms.  Condition well for at least 2 hours and overnight if possible in deep clear water.  Refresh your vase water every 24 hours.    Some growers treat the flowers with Silver Nitrate to extend vase life but we have not tried this technique.

For us, it is the very fleeting nature of Sweet Peas that gives them their charm.  In arrangements exploit this simple charm creating uncluttered arrangements with delicate fillers like the lime green flowers of Alchemilla mollis (Lady’s mantle).

Most of all position your arrangements in the house so that you can to breathe in and enjoy that wonderful fragrance.

Further details

Hardy climbing annual

Origin:  Sicily, Cyprus, southern Italy and the Aegean Islands (ref: Wikipedia)

Latin name:  Lathyrus odoratus

Family: Papilionaceae (ref: RHS) – legumes, peas and beans family

Height:  6-8 feet

Flowering period:  Late spring to summer

Cut flowers:  Yes but have limited vase life.

2018 progress update

4 Jan 2018 – seeds sown

18 Jan 2018 – seeds germinated

23 Jan 2018 – seedlings moved to cold greenhouse to grow on in cool, light conditions

14 March 2018 – tips pinched out and staked

New Sweet Pea plants with the tips taken out and staked to stop tangling and possible damage (14 March 2018)
New Sweet Pea plants with the tips taken out and staked to stop tangling and possible damage (14 March 2018)

4 thoughts on “Sweet Peas (Lathyrus odoratus)”

    1. Our greenhouse is not heated at all. We don’t keep an accurate measure of the temperature but in our part of the world (UK Midlands) we only get very short snaps of cold weather and the temperature of the greenhouse never gets down to more than a few degrees below zero. At these temperatures the sweet peas seem fine.


  1. I love this post! I love sweet peas! I sow mine direct in mid-March (I’m in Kent). It reduces the faff, but I do miss keeping a close eye on them. They are my favourite cut flower for scent and ease of growing.

    Liked by 1 person

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