How I Grow Exhibition Sweet Peas

Two things to remember. First, this is just my way of successfully growing sweet peas; it is not the only way. Secondly, rely on your own experience and experiments rather than believe what you are told by others regardless of their experience.   

 This is what I do to grow exhibition sweet peas.  It is October 27th. 

I  use a cleaned and washed surface,  New Horizon Multipurpose peat free compost and three inch pots.  I have used other mixes of compost and sharp sand but find neat compost more than adequate. 

Sweet pea seedlings are quite hardy and survive well in a cold greenhouse like mine; if they are not over watered.  The commercial guys keep their seedlings in a gently heated greenhouse and this means that they could be watered more frequently without too much danger of damping off.  

I use New Horizon multipurpose compost on its own.  One seed was planted in each washed three inch pot. 

Labels were then written giving the date, genus, species and variety.

Writing the labels on top of a crate made it a little easier.  The labels were inserted in each of the pots. There is nothing more irritating than forgetting which variety is sown in which pot. 

 As it was raining I left the pots outside to be watered by the rain. If it had not been raining then I would water either with stored rain or tap water. I think that rain is better than rain water from the butt and this is a lot better than tap water stored in the butt which is a lot better than water from the tap.  To get an explanation as to why I think this you will have to read my book.  

The pots were returned to the greenhouse after getting a thorough watering and lined up on the staging of my cold greenhouse.  They will remain there until March next year. 

Pencil is an adequate writing implement for labels.  It does not come off easily, which was witnessed yesterday when I had to resort to using silver soap to clean the writing off the plant labels.  

The 2011 October sown seed have germinated Wednesday 9th November.  

I usually sow sweet pea seeds in the autumn.  October seems to be the best month.  Having said this I have successfully sown sweet peas in all the winter months now.  As the seeds came late this year 2012, I have sown them in December.  I have not done that before and will be quite interested in their germination rate. 

 I do not nick, sand or any other way mutilate the seed.   I find that they germinate well without damaging the outer shell of the seed.  I think that if the seed do not germinate, it is more to do with the viability of the seed rather than the thickness of the seeds outer coat. The pots are left in the greenhouse overwinter.  It is a cold greenhouse with no heating at all.
 

This is where the sweet peas will be planted this year (2011).  The ground is raised because I have added so much organic matter to the soil.  I triple dug it in winter 2010 so in 2011 I didn't think that it particularly needed anything serious like cow muck added.  

I think that there is a misconception about just how deep you need to trench for sweet peas.  Well, I don't think that you need to trench at all if you don't want to.  If your soil is well cultivated there is no need to dig big holes.  However, if you do trench it will produce some good plants.  I don't just trench along the sweet pea lines but double dig the whole bed.  I take out a trench that is one spit ( length of the blade of a spade) deep. I take out all the loose earth and then fork the bottom of the trench to a depth of one spit.  Then I add well rotted compost or manure to the bottom of the trench.  This is covered with the topsoil from the next trench.  So that is more or less double digging.  I like to do it but it probably is not necessary - even to get exhibition standard flowers.

There were a lot of weeds between last years onions and leeks so I dug the weeds in as a green manure with the fork but I did not use any other fertilizer for the sweet peas.  The onions got a lot of inoculated charcoal last year and that was noticeable in the ground.  I put in tree posts to give the rows of canes some stability because we have some quite wicked winds on this exposed north facing hill.

 When the seedlings have grown their second or third leaf, I pinch out the growing tip to encourage side shoots. The strongest side shoot is left while all the others are removed. Some growers leave two side shoots. From what I have seen of other sweet pea growers, this is quite an important thing to do if you are growing exhibition standard, cordon sweet peas.

 Let me emphasise again the importance of pinching out the growing tip (the apical meristem) in producing a stem that will produce very large flowers.  If you don't do this you are likely to get a lot of smaller flowers.  Either of the two side shoots will produce much better flowers than the main stem itself.  Don't ask me why because I don't know.  Some people allow both of the side shoots to grow but I cut out one after I have planted them outside.  

 

These are the February sown sweet peas.    I used a commercial seed compost that was given to me. One seed was put into each pot with a little mycorrhizal fungi.  This is the first year I have used mycorrhizal fungi when planting seeds.  All these were pinched out when they had their second leaf. I planted these outside after I had put up the canes for them in March.  They seem to be quite hardy and a few frosts will not hurt them.   

So when is it best to sow exhibition sweet peas  October or February?  The only difference I can see is the autumn ones are going to flower first, however the winter ones are catching them up remarkably fast.  I don't think that it matters when you sow them - particularly.   If you can sow them in October, then there is more time to pinch out and for the side shoots to develop.  Severe frost will kill them though and, unless you have some means of heating the greenhouse, you might loose the lot.

 I am planting out my sweet peas next week 12th to the 16th March 2012 but I need to get the supporting canes up as soon as possible. The sweet pea seedlings are hardened off for about two weeks before planting out.  The sweet pea seedlings being put outside during the day and put in the cold frame during the night.  

I got quite a few Oban Bay sweet peas to survive the winter and they made up the majority of October sown seedling.  Others were Anniversary, Angela Ann, Lilac Ripple, Ethel Grace, Charlie's Angels, White Supreme,  and Dynasty. There were about 17 plants in all.  I planted them along the first row of sweet pea canes.  I watered them in with some comfrey liquid diluted with rain water.  I filled this double row with any sweet peas that were left over from the main rows.  

Recently 2016 -2017 the October sown sweet peas have been devastated by flea beetle.  The only way I have found to counter this is to plant them as late as I can.  The sweet pea plants are grown in individual 3 inch pots so they can survive for quite some time.  I do not like the roots to get pot bound but if this is going to avoid flea beetle then it has to be done.  The only other way that flea beetle can be avoided is to grow in a polytunnel (hoop house).  

Now lots of people would say that making a triangular frame is not as good as making a vertical frame.  Some growers object to the triangular method I use saying that when the plants get to the top of the canes they are squashed together; they do not have enough light or air and disease will be encouraged.  I have never had disease at the tops of the sweet peas.  
The sweet peas will not be left to over grow the top.  I like to layer my sweet pea plants and this means that they do not bunch up at the top of the canes.  Layering is when you take the plants off the canes; lay them on the ground and take them up a new cane along the row.  

The advantage of the triangular construction is that it is particularly strong and stable.  We have some high winds up on top of the hill, which knock down a lot of the bean rows.  A strong structure makes this less likely to happen.  

Alternative method

My method

Fiddling around making a cross piece for the main supports is not what I am good at. It is easier to wire one cane to the main supports and then lean the canes onto that.  Having said that, I do think that vertical canes are a bit better and give you healthier plants.

But that is how I do it. And it was the way my father and grandfather did it so I will be keeping with the traditions of my family and use the triangular method.  

It took me several days to erect all the sweet pea canes, although the triangular method is relatively quick because I needed so many of them.  

I decided to plant the autumn sown sweet peas in the allotment on 20th March.  In hindsight this may have been a little early and maybe nearer the end of March would have been better.  I had already put up the canes for them so they were planted with a little mychorrhizal fungi and inoculated charcoal.  There was still some noticeable amounts of charcoal that I used for the onions last year lying on the surface of the soil.  I think that the frost makes stones rise to the surface and this is what happened to the charcoal.  I just collected it up and put it into the planting holes with the rest.

These are the February sown seeds. One stem is selected and tied to the canes.

  
These are the Valerie Harrod and Restormel being planted.  

 

I was watering with rain water to begin with and then with tap water.  Once a week they were getting dilute comfrey liquid.

The seedlings have two shoots because I pinch out the main stem's growing point after about two leaves.  I let these grow on in the soil until they can be tied onto the canes.  When they are big enough to tie I select the strongest and cut off the other side shoot.  Only one stem is taken up the canes. 

The right side have had one side shoot taken off and the other tied to the cane.  The ones on the left have not been done.  They are too small to have many tendrils or side shoots at this stage so they are not too time consuming.  Keeping them weeded and watered are the main jobs.

By early May they have started to grow quite vigorously and need some side shoots and tendrils removed. They also need tying up so they do not flop over.  

 You can see that this Restormel sweet pea is lolling about because I had not tied it up for about 3 days.  They have grown very quickly and you have to keep an eye on them.  If the stem distorts, then the flowers are not as good as they would be from straight stems.  There are no flower buds on this plant although it should be developing flowers fairly soon now.

 In order to keep the stem as straight as I can, I tie the stem or leaves onto the cane with green garden wire. Garden wire is quite a harsh material to tie them up with and it can damage the leaves or stem.  This disadvantage has to be tempered with the advantage of speed.  If I had to tie up each sweet pea plant with string, it would take much longer than the three hours it took to take off the tendrils; remove the side shoots and tie the stems yesterday afternoon. 

By the middle of May the sweet peas have grown quite a lot.  I have to continue to take off the side shoots and the tendrils to keep the strength in the selected stem.  Flower buds are beginning to be formed and although there may only be two flower buds on a petiole at this early stage it is well worth keeping them to see if you have indeed planted each variety in the right rows.  

The plants are over 300mm tall now so they will be forming their first flower buds.  The first flower stalks usually have two or three flower buds.  I am aim to get at least four flower buds on each petiole.  In order for the flowers to be exhibition standard they should be fairly equal distance apart with no big gaps on the petiole.  If you are growing outside, then this is quite difficult to achieve.  Those growing indoors will be able to regulate the watering and feeding to a much higher degree and this means the flowers will be more evenly distributed.

In order to get really big flowers on sweet peas, I take off the side shoots and tendrils on the main stem.  I try to take the side shoots off before they get too big but they do grow very quickly. If you leave them for any length of time, bigger ones have to be removed.  The big ones I cut out with a pair of scissors, while the smaller ones can be pinched out with finger and thumb.

 The sweet peas were not given any muck or leaves this year.  They have only been fed on inoculated charcoal and comfrey liquid.  They have had a little mychorrhizal fungi in their planting holes as well.
By June the sweet peas are at least half way up the canes.

There are some varieties that are particularly suitable for exhibition plants because of their vigour.  Some like Jilly, Restormel, Gwendoline, Charlie's Angels, etc. are big,very strong growing plants that can produce large blooms.  Other varieties are great because they are good for picking for the house or give a really heavy scent but they are not really suitable for this method of growing.

 You need to remember to take off the flowers that have gone to seed - I can see a couple here that I missed. 

Now in the middle of July the sweet peas are up to the top of the support canes and need to be layered.  All this means is; taken off the support canes and laid on the ground.  The sweet pea plants are then taken up a new cane four or five canes down the row.

 Blue Danube getting to the top of their canes. 

 When the sweet peas get to the top of the canes they need to be layered.  This variety is Bristol. 

 The Eclipse at the top of the canes. 

 Some of these Eclipse flowers have gone over and they will be removed before layering. 

 You can't really see it but the petiole on the left has five flowers on it.  If you grow them very well you can get five flowers on a stem. 

 The Valery Harrod and Restormel have been layered

 The Bristol sweet peas being layered. The tops are not cut off because this would stop the stem from growing and producing flowers.  You might get a side shoot to take over but the flowers will not be very good.  So the plants are just laid on the ground and the tops are tied into the canes a little down the row.

If you cut the tops off the plants they will
stop growing and producing flowers.

Restormel growing up their new canes

To make this process a little easier I take off the lower leaves.  These are the big tough leaves and really they are the leaves making most of the food for the plants.  They should not be the ones taken off.  However, they often go yellow so can be taken off in any case.  There is also the dreaded yellow disease that infects the lower leaves and then slowly works its way up the plant. Removing the lower leaves seems to prevent this from happening. The stems lying on the ground can be tied into the canes to keep them away from the pathways.  As some of the sweet pea stem is lying on the ground the stem supported by the new cane is not as high as it was previously.  There is a further length of cane that the sweet peas can be grown up. Extending the canes is not a really practical  because once the plants have reached the top of the canes they will be hard to side shoot and detrendril.  The way that these sweet peas are growing they will be at the top of the new poles in no time at all.  If that happens then I will take them down again and take them up another cane further down the row.


Take four  sweet pea plants off their support canes and lay them in front of the canes.

Layer the next four or five plants onto the vacant canes going behind the canes.  I have not shown the ones in front for clarity.  

After tying up these four sweet peas on the left, you can tie up the sweet peas that were on the ground. (I have not shown the ones behind for clarity.)

This is what you end up with.  This seems to be the most efficient way of layering. 

You can take the plants further along the row to tie them up but you have to make sure that they are long enough to reach.  The further along the row you layer the plants the more cane they have to grow up.  

 I have kept a lot of sweet pea seeds and planted them in pots at the end of October.  They have all germinated well. My assumption was that they would not breed true because of cross pollination between varieties that were grown quite close to each other.

However, it seems that  sweet peas are normally self pollinated.  While this may suggest that all sweet pea seeds will breed true, there is some doubt whether this is always the case.  My sweet pea plants were not protected from cross pollination - they were "open pollinated".

Now I had always thought that a bumble bee landing on the keel petals of the flower would make the stamen pop out and coat the underside of the bee with pollen which would then be taken to the next flower.  The fact that the stamen and stigma are protected by the keel petals seems to give the flower more chance of self pollination.  When the flower has gone over, pollen has been shed and fallen on the stigma which does not normally protrude from the petals giving a self pollinated flower.

If the sweet pea is self pollinated then it should be quite easy to keep varieties pure because they would only change by mutation. This might give the opportunity for saving seed with some reliability that doing so would produce the same variety as the parents.