February 28, 2012

Planning and Planting the Perfect Sweet Pea Crop

It's nearly March 1st, which means seed-starting time - at least for early crops. I too have been guilty of the most common mistake that new gardeners often make -starting their vegetable and flower seeds too early. Most seeds must wait, until the end of March or even mid-April for crops such as tomatoes, but there are some crops that benefit from early kick-starts, and cut-flower sweet peas is one of them. If you love the classic, old-fashioned long-stemmed sweet peas that you sometimes see in stylish weddings and florists,  then you must grow the proper varieties - welcome to the cultivation of the rarely experienced English Spencer varieties of sweet peas. The sweet peas that true sweet pea fans grow, and the same varieties used for exhibition in England, where they are so popular. If you too want to experience these amazing long stemmed, fragrant and colorful sweet peas, now is the time to plant them - starting with seeds.

Growing cut flower sweet peas to perfect takes planning, and dedication. The finest seed should be acquired ( I get mine from Owl's Acre Sweet Peas in the United Kingdom). I find that I do not need to soak seed overnight in water, but you can do that if you want to speed up germination. Do not leave seed in the water longer than 12 hours however, or you risk damaging the embryo - you don't want bean sprouts before you plant them! Plant hard, fresh seed in damp soil, and you will be all set. Leave the soaking to the old-timers and the inexperienced.

Most sweet pea varieties available in the United States are either old strains, those heirlooms with small or bi colored flowers, the fancy stripes and flakes ( those really-vintage red and white flecked forms) or those known as Spencer varieties- long stemmed exhibition forms, which are the most commonly grown long-stem varieties popular in England. There are fine sources in California from some classic names Spencer varieties, but as I spend a lot of effort growing the finest cut-flower methods, I figure that I might as well order the seed that the sweet pea exhibitors grow, from the same sources. You may have just as fine a result from American grown seed, I saw get what you wish, for I've even found some of the old-fashioned Royal varieties nearly as nice, and in fact, if a warm summer is expected, they may perform better.

One of the tricks in growing fine sweet peas is getting the young plants off to a good start. Most professional exhibitors use these root trainer pots ( sold under the brand name Rootrainers). They are costly, but I've found nothing better. Trendy newbies may suggest using toilet paper tubes, which I am also using, but you must be careful, since they deteriorate quickly. The goal is to provide a deep root run, since sweet peas want to send a long root straight down, and the more depth you can provide, the better off your mature plant will be. 

A cultural note here - you may plant seeds directly out in the garden even around March 1st, (even here in USDA zone 5) if the ground is 'workable' but germination may be delayed, and can take as long as a month, wasted time if you want to maximize the cool weather for growth before it gets warm. You will find that germinating seed at 70 degrees F, and then relocating the seedlings to a cool if not cold growing area where temperatures shift from around 65 deg. F during the day, to about 45 degrees F. during the night as ideal growing conditions.

Labels can be created if you want to keep track of the varieties you are growing, or, if you are like me, to remind myself which varieties I did not order, since  I just decided to order all of the other varieties that I did not order the first time around.

Fresh seeds are planted into the Rootrainers, as soon as the seed arrives in the mail. I use a professional soiless mix ( ProMix) in which to start seeds since it is sterile, and the texture is perfect. Seeds are pressed into the surface of the soil, with the eraser end of a pencil and once watered well, I check again to make sure that the seeds are completely covers. The seed trays are then brought into the house, where this sit on a warn shelf above the over until I see shoots emerging - which takes about six days. Then then are imediately relocated to the greenhouse, where it is much cooler.


This one flat was brought out to the greenhouse and placed in the full sun by Joe, who forgot to water them. Pea shoots are very tender at this stage, and one hot sunny day, even if it is February, can roast the tender tissues. I lost four rows and two varieties ( of course, the ones that I had no extra seed for!). Typically I would lose seedlings to mice, but I've set traps in anticipation, two weeks ago, and we've caught four already. I took photos but thought that I would spare you the images. I am certain that there are more ( like, maybe 30?) so the traps are still set with peanut butter, our bait of choice. My fear is that one of these mornings, I will walk in and see every pea plant chewed off to the ground ( again) since that is what happened in October with my winter-blooming greenhouse crop, but I am banking on the fact that our mouse population is satiated with their steady diet of Rhodohypoxis ( remember those large, wooded trays with a few hundred bulbs each that I grew my collection into? They are all gone. every single one. <sigh>. Time to get us some terriers.......no, wait a minute....  ugh. We have the only Irish Terriers in the world who prefer Brussels Sprouts over mice.

A good example of why root trainers work. This seedling ( sun roasted on the top) shows just how fast and how straight the sweet pea roots want to grow. This root is nearly 6 inches long, in just 2 weeks. Seedlings will be pinched back once they produce their first set of true leaves, which will stimulate a side growth which will be surprisingly more aggressive. It's always hard to do, but once you get over the first pinch, a finer crop of sweet peas will be in your future. Now? Off to order new bamboo poles to construct the cordons on which I will be training this crop.


  1. There was a man in one of the community gardens in Santa Monica that did a ton of sweet peas. I used to press my nose up against the chain linked fence trying to catch a whiff of their fragrance.

    I have some started and may start some more but here in CA fall is the best time to plant them and of course I wasn't living here in the fall.

    They are definitely up there with my other favorite plants. I love the little packets your source sends them in.

  2. hopflower10:07 AM

    LOL! You don't really "have to have" rootrainers, but they do work well. I don't always use them and have been growing sweet peas for years. The trick is getting them off to a long, slow start to develop strong root systems. Nice post, Matt. Glad you are getting the sweet pea virus-it is the best one around I think. I'm addicted. Mr Rowland has some of the finest seeds around; although there are many sweet pea seedsmen, you cannot do better than his!

  3. Thanks so much for this tutorial. I remember being sorely tempted to try them last time you posted about the long-stemmed florist stock for sweet peas. Thanks.

  4. Anonymous7:03 PM

    You can get these from Johnnys seed for half the price
    Why not support an american farmer

  5. You are correct, Johnny's Selected seeds carries a mixed blend of older Spencer varieties which is very fine. In fact, if you read any of my vegetable posts, 90% of my seed comes from Johnny's. I try to order most of my seed from Johnny's for many reasons, but especially because they grow their own seeds here in New England, and they are very responsible growers for food crops, as well as with their breeding programs.
    This year I wanted separate colors of Spencer Sweet peas, and for this trial, I also needed newer crosses which are not available in the US. I have orders Spencer strains named from four US sources, and one British source. ( I prefer to always buy my seed from the breeder if possible). As for supporting US farmers, That's fine - but I also believe that plants know no borders, and so, I seed authenticity and quality first, and sometimes this means that I must order some seed from other countries. Thanks for your note and for sharing Johnny's as another source.

  6. An interesting blog. I am glad that I am not the only sweet pea enthusiast blogging.


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