By Roger Parsons

Wouldn’t it be good to achieve the length of stem and size of bloom of exhibition sweet peas without all the time and effort involved in cordon culture? Several people have asked how I manage to win classes at the National shows using bush grown, or naturally grown, Sweet Peas. Usually my vases are a mixture of bush and cordon grown stems but in 2006 a few were entirely bush grown. The following explains what I do in the hope that it may help others.

Plants are autumn sown; in recent years this has meant the beginning of November on the South coast because of the relatively mild winters, equivalent to USDA hardiness zone 6b. Seeds are sown directly into Rootrainers, one seed per cell, since this avoids the work of pricking out and germination is approaching 100%. I do not pinch out the tops of plants as this will encourage side shoot development when it is root growth that is required at this stage. Pinching out reduces the preciously small leaf area for photosynthesis and changes the balance of plant hormones. Side shoots develop naturally enough in their own good time. I just look over the plants in mid February and pinch out the odd one that has failed to initiate side shoots. I like Rootrainers because the roots grow downwards and avoid spiralling around the bottom as in other containers. They are quick to use when removing plants at planting out in early to mid March. The plants grow away quickly without a check to growth.

In the early stages of growth I want plants to build up as much strength as possible so even my cordons have all side shoots left on until mid May. In the case of cordon plants, the strongest shoot is tied into the support in mid April but the naturally grown plants can send up as many shoots as they want. Since these are primarily grown for seed, I plant in nursery rows about 6m (20 feet) long and plants are supported by plastic netting of 15cm (6 inch) gauge.

My soil is deficient in potash so just prior to planting out I incorporate a good dressing of sulphate of potash plus a little superphosphate to help the roots establish quickly. The latter is perhaps an unnecessary expense with such fertile soil; better safe than sorry! The final ingredient of the pre-planting cocktail is calcified seaweed since lime is used up as the manure breaks down and my pH is naturally around 6.0 to 6.5. The key to success is primarily in the soil. I am growing on Grade 1 agricultural land so I started with a good depth of fertile topsoil. Those without this may still have built up a good soil profile through long cultivation. If not, now is the time to start. Horse manure is cleared from adjacent paddocks and stacked to rot down and I incorporate this into topsoil along the rows during winter cultivation. I don’t find it necessary to cultivate the subsoil. Stable waste is spread between the rows straight from the stables. This means that by the end of the winter, the whole plot is mulched in up to 15cm (6 inches) of relatively fresh stable manure. Some may think a fresh manure mulch is too rich but it consists largely of straw or shavings which use up nitrogen as they rot down so that I have not had any problems. I am convinced it is the mulch over the plot which is of main benefit since the plants need no watering once they are established. It doesn’t matter what the plot is mulched with, old straw was traditional, so much as the depth: a minimum of 10cm (4 inches) is recommended. It is really a case of whatever is available locally that is cheap and plentiful.

Weed control is still required despite the mulch. Coarse weeds seem to thrive as much as the Sweet Peas. Pest and disease control remains important. But the only other work compared with cordons is occasionally weaving plant growth through the netting. Plants grow very strongly in these conditions but coarseness is avoided through allowing all side shoots to develop. I would not encourage keen exhibitors to try this as an alternative to cordon culture since stems are more vulnerable to damage by wind and neighbouring tendrils. Such losses may be compensated by the sheer volume of blooms produced from all those side shoots but you would not want to have to rely on them for a show. The above will I hope provide a guide to those who simply want to have good stem length when cutting blooms for the home or to support their local flower show. It gives me a useful supplement to my cordon-grown Spencer blooms for the bigger shows. It is particularly useful in achieving good quality blooms for vases and bowls of old fashioned and semi-grandiflora varieties where you would not want to bother with cordon culture in any event.

One final comment. Part of my plot is shaded by trees in the middle of the day but gets plenty of sunlight during most daylight hours. I have found in the past two years, when we have had exceptionally hot weather, that these plants have performed best of all. Most of the blooms in my ‘Garden News Class’ entry in 2006 came from these naturally grown plants. It leads me to wonder if I should provide shade netting over the rest of the plot, covering and removing during the middle of each hot sunny day.