St Patrick’s Day Sweet Peas

how to grow sweet pea for St Patricks day fun

Now is the time of year to plant sweet peas and although they are traditionally planted on St. Patrick’s Day, it is recommended that when planting them into garden beds, the soil is prepared at least a week earlier. The correct preparation now will ensure a spectacular display right through into spring.

Soil preparation:

Sweet peas love full sun and a rich soil. Find a sunny site and dig in plenty of organic fertiliser. For best results, use 5IN1™ Organic Fertiliser. Sweet peas also love a slightly alkaline soil, so you may need to add some lime or dolomite to the soil before planting. As a guide, apply approximately 150g lime or dolomite to each square metre of soil. Sweet peas like a soil pH of about 6–7, so if you have a Searles Soil Testing pH test kit, test the soil to see if it needs lime or dolomite. Remember that once the soil is limed, the lime will take effect slowly, so you will not be able to accurately measure the final result until a couple of weeks after application.

Trellis support:

The next step is to make sure you have a good, strong trellis in place to support the sweet pea’s vigorous growth. Do this before planting the sweet pea seeds. This way you won’t disturb the seeds once they are planted.


Traditionally, sweet peas are planted on St. Patrick’s Day (March 17), but in warm climates they can be planted right through until the end of April. Plant the seeds about 3cm deep and 7cm apart. This will give a good mass display. Cover them with Searles® Propagating Mix and lightly water it in. Once the seedlings have four sets of leaves, nip off the top of the plant to encourage more side shoots.

Sweet Pea - Plant on Saint Pats Day


When fertilising sweet peas, it is important to remember that they make their own nitrogen and don’t like being fertilised with extra nitrogen. An ideal liquid fertiliser is Searles Liquid Potash, which contains both phosphorus and potassium. For excellent flowering, feed your sweet peas every 2 weeks with Searles Liquid Potash from the time seedlings emerge right up until flowering.

The first flowers buds to appear are usually single blooms and these should be removed to encourage the production of flowering stems with three and four blooms on them. Sweet peas make superb cut flowers and to prolong the life of your plants, pick the blooms every day and give large bunches to your friends and neighbours!

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