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Notes on Growing Sweet Peas

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Seed

Always purchase good quality seed from a specialist supplier who offers a good range of the best modern varieties. Seed should be uniform, give virtually 100% germination, and be true to type. Cheap, field grown seed of obsolete varieties will inevitably give poor results.

Sowing

Starting some sweet pea seedlings indoors in pots is a good idea as a back-up to seeds which don't germinate outdoors in your beds. We start ours in 4" pots in cold frames at the same time as we plant outdoors (early to mid-April). We use Promix for seed starting in pots. Germination is often quicker and more uniform if the seeds are soaked in water for 24 hours immediately prior to sowing. This also enables you to identify any seeds with hard coats, which fail to swell during this period. These should have the seedcoat nicked with a small file to enable them to take up water. A temperature of 55 - 65 degrees fah. will give rapid, even germination. It may be necessary to protect newly sown seed from mice.

Direct Sowing

Sweet peas can be sown direct into the open ground where they are to flower. The best time for this in Downeast, Maine is mid- April, depending on the weather and the locality. Sow 1 - 2" apart, about 1 - 1 1/12". Plant in double rows approx. 6" apart on either side of your trellis. The use of inoculant is recommended when planting outdoors. Germination can take between 2 - 3 weeks. Slugs and mice can be a real problem on a direct sown crop, so take suitable precautions before you sow.

Planting times for different regions

California - August to September for early spring bloom, November to January for summer bloom.

Southwest, S. Texas, S. Florida - September and October

Lower Southern states - November, December, January

All other areas - February through April

Cultivation Site

Choose an open site which gets plenty of direct sunlight, but which has some shelter from the worst winds. Avoid planting close to an established hedge or where there will be competition from tree roots. Plant rows from North to South for best sun exposure. A trellis system will be necessary as the plants, being vines, require support to flourish and flower. We plant in block rows to create a micro-climate which keeps the plants protected. Each row gets a 8-10' trellis using chicken wire.

Preparation

Best to prepare your soil in the fall. Have your soil tested and amend as required. Sweet peas like to be planted in well drained soil which has lots of good quality compost (manure based works well) added to it. Compost will add to your soilÕs moisture holding capacity. They like a ph of approximately 7.0.

Watering

Young seedlings can be prone to disease if over watered, but once the crop is in full growth, a copious supply of water is needed. A well prepared site will pay dividends by having considerable reserves of available moisture. It is essential to encourage early establishment and a strong root system if high quality flowers are to be achieved. They like about 1" of water per week, one good soaking is best.

Feeding


Ideally a sweet pea plant will derive much of its nutrition via its mycorrhizal symbiote, particularly nitrogen and phosphate. High levels of potassium are beneficial in encouraging firm, disease resistant growth but must be balanced by suitable levels of magnesium, as increasing the concentration of potassium in the soil inhibits the uptake of magnesium by the plant. For this reason heavy dressings of potassium sulphate will often lead to symptoms of magnesium deficiency. When seedlings get to be about 5 - 6" tall, feed with diluted fish emulsion, organic fertilizer or manure tea every two weeks for about one month to give the plants a good start.

Mulching


When plants are about 5 - 6" tall apply a good quality straw mulch. I apply at least a 4" layer. Avoid cheap hay mulches as they are weedy.

Harvesting

Flowers should be cut every few days to encourage continuing bloom, a certain delight! Flowers can be put right into a solution of lemon-lime soda (sugar and acid) and water for a longer vase life. Use 2 parts water to one part soda.

Physiological Disorders

Bud Drop This is one of the great scourges of sweet pea growers. The most common are dull weather when the plants are growing vigorously, and erratic watering. The problem will often resolve itself with a change of weather conditions.

Pests and Diseases

Sweet peas have excellent natural resistance to pests and diseases, and the best defense is to encourage healthy growth and a strong root system. This is, however, not infallible, and the following notes may prove useful.

Aphids

These are becoming increasingly resistant to chemical sprays, and are important as major vectors of virus. Encourage ladybeetles and lacewings and resort to chemicals only if unavoidable. I use a mix of Ivory liquid and water (5 gals water to 2 TBSP soap) to fight aphids. Generously spray the affected plants on an overcast day. The next morning spray those same plants with water to rinse off all the soap residue. Soap residue will burn the foliage when exposed to sun. This usually does not kill the plants, but they will not look good and the plants will take about 3 weeks to recover and start blooming again heavily.

Leaf Hoppers

Minor pests in themselves, they can transmit virus diseases from other plants in the vicinity, especially clover. Try to eradicate any nearby patches of clover.

Powdery Mildew

This appears as powdery white spots on the upper surface of the lower leaves. Can be destructive in dank weather and on older plants. Cutting off old leaves from lower part of the plants may help by improving air circulation, and reducing the source of further infection.


 

 


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