The Somerset Sweet Pea Co

The Importance of Autumn sown Sweet Peas

I have heard it so many times at Sweet Pea Shows, Exhibitions, or Demonstrations ”How do you get such long stems and large flowers” Well there is no secret or mystery its just a matter of applying some basic horticultural principles.

  • Most importantly Autumn sowing of seed.
  • A good quality source of seed or Autumn grown plants.
  • Soil cultivation.
  • A little care and attention.
Autumn Sown Sweet Peas

Autumn sown Freak Sweet Peas

To produce best results there’s nothing like Autumn sowing, this does entail some additional care of the plants during winter, but Autumn sown plants flower earlier, have longer stems, larger flowers and flower for a longer period. Good results can be achieved with spring sown, however they are not the same and do not achieve tip top quality. Almost unrecognisable as Sweet Peas, these freaks are Autumn sow Sweet Peas and will go on to produce far superior blooms.

Spencer Sweet Peas (The type we are dealing with) are a type of day length plant. This means the flowering period is governed by the length of day light. If you sow your peas in early November, they will make slow, steady growth during winter (particularly the roots) and after planting out, until late May early June when, give a week or two, flowering will commence

So if you sow your peas in early March (spring sown) once germination has taken place growth will be rapid, and by mid June when the plants start to flower, they are doing so without the advantage of having maximised their root system.

    These are generally the Sweet Peas purchased from garden centres during April. At Somerset Sweet Peas all our Sweet Pea plants are sown during November/December and are grown hard, outside in cold frames to exhibition quality.

Cordon Cultivation

Cordon grown, similar to tomatoes. With this method all side shoots and tendrils are removed and the plant is ringed at intervals to hold in position. This makes the plant concentrate its efforts on producing large stems and flowers. This method is generally used by Exhibitors and is labour intensive however the results are remarkable.

Bush Cultivation

Bush, sometimes known as clump cultivation, is when a whole pot full or several plants planted separately, are allowed to grow up a structure independently with an occasional tying in should it be required. With this method the flowers are early and the first flush have large stems and flowers. However if not picked regularly the length of stem or Spike soon deteriorates but the sight and smell of a clump in full bloom is something special.

Autumn sowing of Sweet Peas used to be carried out in early October in the north of England, and mid October in the south. However due to global warming, sowing now takes place during early to mid November. There are many myths surrounding the sowing of Sweet Pea seeds, its this simple soak the seeds over night and in the morning check to see if the seeds have swollen if any haven’t they need to be chitted once chitted return the seeds for a further 4-5 hours this will allow the seeds to imbibe and start the growing process giving even germination, and a uniform emergence. At Somerset Sweet Peas we recommend you sow the seeds initially in half trays of 1/4inch (5mm) sieved” J Innes Loam base seed compost” or a soiless compost, perlite or vermiculite. Fill the tray to within one 1 inch (25mm) of the top, position the seeds 1 inch (25mm) apart, then with a fine rose watering can water the seeds and compost thoroughly. Repeat several times. Then cover the seeds with compost to the top of the tray but do not water. Add a few slug pellets.

Sweet pea seedlings

Sweet Pea seedlings at the ideal stage for transplanting. At this time of year depending on the weather, a little heat may be required say about 15c-18c for a uniform germination. However once the seedlings have emerged they must be transferred to the outside or a cold frame immediately (this is very important) to stop the seeds becoming leggy or Etiolated.

From now on the seedlings must be grown hard with no undue coddling.

Transplanted seedlings

Transplanted seedlings

Once the seedlings have grown to about 1″1\2 inches (36mm) high with the leaves unopened this is the best time to transplant. Five plants to a 6 inch (150mm) pot. Fill the pots with 1/4 inch (5mm) sieved” J Innes No1 loam based compost”. Make a hole with a pencil, tease out the seedlings and before transplanting into the pencil hole just nip off the tap root at the bottom. This will encourage a strong secondary root structure and plants will be easily transplanted in the spring when the tap root, if allowed to develop, can reach 2 feet (600mm). When transplanting is complete tap the pot to settle the soil and add slug bait.

During the growing on period I cannot stress the importance of growing the plants hard (do not put in the green house). Seedlings must be put outside in an open frame without the lights, and should only be protected in cases of severe frost -4 and below. The frame should be positioned in an open aspect, full sun if possible and not in a dark dingy alley. Wire mesh protection against mice is a good idea and some cover should be given if snow is forecast, as this can break the stems, if it is of any depth.
Sweet Peas transplanted with ease (note simple pencil hole).

A word about the frames, high walled frames are of no use to sweet pea cultivation, the ideal is 12inches (300mm) high at the back sloping down to 8inches (200mm) at the front, 4 feet (1200mm) in length and 2 feet (600mm) wide with removable lights and 10mm chicken mesh frames. These days the lights are rarely used except for extreme frost and cold, but can be replaced with the framed mesh for mice protection. Position is critical south facing with full sun if possible .

This may all seem a little complicated, however if you are only growing a few pots there is no reason why you cannot just leave on the patio providing:

  • Sheltered from Northerly and Easterly winds

Mice and slug protection (cat, slug pellets)
Protection in extreme weather (move to a cold green house only if extreme weather persists.)

About the beginning of January the plants should be removed from the frames and inspected to see if any side shoots are forming at the leaf axis, (these side shoots will go on to form the main stem and flower), if not the plants should be stopped. This means pinching out the main shoot at the top, if side shoots are breaking then the plants can be left unstopped. However whilst the pots are out of the frame take the time to fluff up the surface of the soil, and top up soil in the pot. This is also a good time to renew slug bait.

Ground Preparation

Site Considerations

Firstly we must take into consideration the site position, full sun is best, however if growing less seriously just for cutting try to ensure a fair period of sun . Wind protection from the East and North if possible especially after planting out. It does not matter when you carry out soil preparation on light soil but do not leave it to the last minute as bad weather could delay you, and in turn planting out, it’s important to plant out at the end of February.

Light to Medium Soil

If you are going to grow clump fashion just dig the top spit out of a square yard/metre and put to one side then add a barrow full of well rotted compost, manure, or any organic matter you can lay your hands on. Add a good handful of blood fish and bone, then dig in to the bottom spit. Turn over a few times breaking up any large clumps of soil as you go, return the top spit and let the weather have it. Simple as that.

Heavy Soil

Heavy soil is hard work whatever you are growing, however we can employ a few tricks to improve the growing conditions. Firstly digging heavy soils should be carried out as early as possible, ideally during September/October, this allows the soil plenty of weathering. Preparation is the same for light soil but add half a bag of sharp sand with the organic matter in the bottom spit, and if possible import a little top soil and add to the top spit. Leave the soil rough and allow it to be weathered with the additional materials added. This will raise the soil above the surrounding area and will assist with drainage and the soil will warm quicker in the spring.

Planting Out

Autumn grown plants are best out at the end of February. The seedlings, if grown hard should be 4-5inches (100mm -125mm) in length with one, two maybe three side shoots about 1/4inch (5mm) long depending on how the winter has been.


Autumn sown plants

Autumn sown bare root plants ready for planting out

Root trainer grown sweet peas

Autumn sown sweet peas in root trainers.

With day length growing longer, growth will be rapid and if you are not careful the roots will be difficult to separate when transplanting. Do not be frightened about the cold, properly grown plants are always ready. However the following considerations should guide and not the calendar. The weather should be favourable dry and mild, planting in the cold is perfectly acceptable providing that frost is not in the ground. Give the plants a good soaking a few days before planting.

If growing clump fashion, it’s perfectly acceptable to knock out a pot of seedlings and plant out as they are, without teasing the root ball apart. However though more time consuming, but a better method with superior results, tease the root ball apart, separate the seedlings and plant 7inches (175mm) apart.




The ideal planting method

The Ideal planting method

The ideal planting method is using a boarder spade (ladies spade) creating a 45 degree angle then spreading the roots across the angle, the soil should be level with the lowest shoot. Next you need to erect some support. I personally don’t like wigwams as they suppress the natural growing habit, but if that’s all you have its fine, good results can still be achieved. However a superior method if available is tall bushy pea sticks about 6feet (1200mm) high (hazel, pussy willow) cut during the winter and pushed around the transplanted seedlings and tied in at the top. Additionally position some small twigs around the seedlings for initial support (DO NOT FORGET SLUG BAIT).At Somerset Sweet Peas we sell manufactured circular wire supports that remove the hard work and can be used for twenty or so years, also useful for runner beans and peas.

Growing on The Early Stages

From planting out to cutting blooms may take up-wards of three months or so in the case of Autumn sown plants, less for spring sown. An important period this if aiming for tip top quality. Generally plants can be left to get on with it, however keeping a vigilant eye will keep the grower one step ahead of any potential problems. Theres a lot to be said for walking the plot every other day, mice can still be a problem eating young shoots and damaging plants by trying to eat the old seed if still attached. Traps can be deployed at planting, but due care must be taken so birds cannot be trapped. Crates can be placed over the traps with small entrance holes either end and secured to stop foxes running off with the mice/traps. Repeat applications of slug bait,. A brief word on slug bait, you don’t need to throw massive handfuls so the plot resembles a blue sea. Slug bait is an attractant, 2-3 pellets around each plant is more than sufficient, slugs will eat the bait before the seedlings. We recommend the shower proof type that contain Metaldehyde as the active ingredient.

During March plants will settle in and root growth will start to “tick over” we don’t want top growth at the moment. As the days lengthen and the soil begins to warm, top growth will quicken but on a fully established root system. Try to keep the plants upright with a few ties of raffia to adjacent twigs or canes, wire rings can be used with the same effect. During May on a warm sunny day it pays to put the hoe to work for several reasons. Weed seedlings will commence to grow about now and can be snuffed out early. Breaking the soil surface will help the soil to warm up and dry out if a wet season, and allow any trapped stale air from the soil to escape and be replenished with fresh. Hoeing should be shallow, try to keep clear from stems of young plants.(hoeing on a nice sunny spring day – bliss)

The Flowering Period

Generally autumn sown sweet peas will start to flower at the end of May beginning of June depending on how the weather has been. The opening of the first bloom and the intoxicating scent (7-8 months since the last sniff) is indeed a pleasure. Whether growing cordon or bush, blooms will then appear regularly, and cutting young and often (with top bloom still in bud) ensures minimum drain on plant energy and continuation of flowering. Some Cultivars drop their buds early on, and later too, during unfavorable weather conditions especially when a warm spell with bright sunshine is followed by cold/frosty, dull/poor light.

Soil preparation and set up for Cordon Cultivation

This is how exhibitors grow sweet peas for showing/exhibition. The stems are longer with larger flowers. If you are going to grow some sweet peas from Autumn sown, you are half way there. For a little extra effort, the results are quite remarkable and maybe I can tempt you to enter a village five at your local show. Sowing and growing on is the same, ground preparation is a little different, and the supports take a little effort.

Generally exhibition sweet peas are grown in double rows, north to south so the plants get equal amounts of sun. Rows should be 3 to 4 feet (90cm-120cm) wide depending on how you feel about digging the extra. This work should be carried out in the early Autumn to allow the weather to have the soil. You will get about 11 plants per yard/metre run. Let’s say we are going to have a 3yard/3m run of trench. Start by marking out the trench with some string and take out the first spit and place to one side. Turn the bottom spit once, and add a bucket of well rotted manure or compost, a handful of bone meal and 3-4 handfuls of wood ash, if available, per yard/metre run of trench. Turn the bottom spit again breaking any large lumps as you go, replace the top spit in 6 inch/150mm layers breaking up the soil as you go let the weather do the rest.

About the beginning of February apply a handful of blood, fish and bone per yard/metre run of trench and rake in. If just growing 3yards/metre the bamboo canes can be put up runner bean style. Some people prefer to put the canes in before planting, I prefer after planting. The 8foot/2.4m canes should be a foot/30cm either side of the centre, 7inches/175mm apart, tied at the top with a central cane running the length of trench. This gives the flower spikes the best angle to grow straight. Straight stems are essential for exhibiting. If growing many (and some exhibitors grow hundreds or even thousands) there are easier methods for fastening canes using fixing clips on wire supports.

Planting out should be done during mid February on light soil, and mid March on heavy soil, in the South of England and 2-3 weeks later in the North. However it will depend on soil conditions and the weather. Don’t forget slug bait after planting out. If only growing a few, say 10-15 plants as an experiment to see how it goes, an easier method is to make a wigwam with canes

Growing On

About the end of March to mid April as the days lengthen and with temperatures beginning to rise, the young plants will start to grow apace and plants must be tied/ringed to keep upright. The ideal plant having one, two or even three shoots. Once they reach 18inches/46cm the plants must be restricted to one leader, by choosing the main shoot and removing the others. The chosen one will go on to produce flowers. Side shoots and tendrils are also removed from the leader. Flowers should appear about the end of May beginning of June and should be cut young and often, top bloom still in bud to minimise drain on the plants resources.


As you can imagine once the plants reach 5 Feet/1.5m tall you are going to run out of cane, so we carry out a process called layering. This entails laying down the plants to the right or left and starting again. Take this opportunity to weed between the rows, and add slug bait before layering. Try to carry out during a dryish spell and not directly after rain as the plants are very turgid, (I remember my first attempt at layering the first two plants I layered snapped, not good odds with a further 398 to go) but you soon get the hang of it. Remove all the wire rings except the top one this should be the last ring to be removed, then holding the plant with one hand remove the ring with the other hand. Then gently tease the plant free from the plant next to it. It pays to leave some space at the end of the trench so 5-6 additional canes can be added. The plants can then be laid down along the ground to the nearest free cane. Repeat with the next plant until the row is complete. If layering a double row the first few plants of the second row, are layered across the trench and round the canes of the first row. After about 12-20hrs depending on growing conditions, the growing tips with turn up and you can put your first wire ring on them. In an ideal world all the plants would be the same length, however you may have to delay the first wire ring until the plant has grown sufficiently to reach the next cane. About this time you can feed your peas with a high potash feed, tomato feed is ideal at half strength.

Layering of Sweet Peas

Layering of sweet peas.

Depending on the type of season (extreme heat can reduce the season considerably) you may have to layer 3 times.

Rows of layered sweet peas

Rows of layered sweet peas.


This is an important part of sweet pea cultivation. Sweet peas must never be allowed to dry out, drying out will cause flower stems to shorten and length of stem will not recover, mildew can also be a problem during dry conditions. Damping down of the surrounding area and spraying the foliage with cool water is beneficial during hot spells.




Cordon plants in full bloom

A row of Autumn sown cordon plants in bloom.