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