Sweet peas: varieties, hardiness & growing tips

Sweet peas have been a popular plant for balconies and gardens for many years. You can sow the annual sweet pea yourself and even easily breed your own colourful varieties.

Sweet pea (Lathyrus odoratus), has enjoyed great popularity as an ornamental plant in the garden for centuries. This beautiful garden vetch is attractive, although its flair is a bit old-fashioned. Nevertheless, it is sure to come back into fashion soon. In this article you will learn all about the correct location of sweet pea, sowing and, how to propagate sweet pea from seed. Of course, you will also learn everything important about the choice of soil and about the care measures.

Sweet pea: origin and characteristics

Sweet pea is a member of the legume family (Fabaceae), as are peas (Pisum sativum), beans (Phaseolus vulgaris), and lupins (Lupinus spec.). It originated in the Mediterranean region but is widespread throughout much of the Northern Hemisphere. Lathyrus odoratus is an annual herbaceous climber, which, depending on the variety, reaches 1.5, and in some cases even up to 3m in size. The leaves of sweet pea are pinnate and have delicate leaf tendrils with which the plant clings to anything it can entwine. Sweet peas not only delights garden lovers with their abundant blooms from June to about September but also provides food for bees and other beneficial insects. The colour palette of sweet pea varieties ranges from white to pink and red to blue and purple.

The most beautiful species of sweet pea

Since sweet peas come in a wide variety of colours and growth heights, here we present some of the best varieties.

• Lathyrus odoratus ‘Cupani’: sweet pea ‘ Cupani ‘ is one of the largest cultivars, growing up to 3 m tall. Sweet pea delights with purple and dark red flowers from June to September.

• Lathyrus odoratus ‘Painted Lady’: This variety is among the oldest of the sweet peas and delights with pretty, bicoloured flowers, which are white inside and pink outside. Sweet pea ‘Painted Lady ‘ grows up to 2 m high and blooms from July to October.

• Lathyrus odoratus ‘Lord Nelson’: Also a historic sweet pea is the cultivar ‘ Lord Nelson ‘, which dates from 1907. It grows about 1.5 m high and has strong dark blue flowers.

• Lathyrus odoratus ‘Bijou Mix’: This is a colourful mixture of different coloured flowers, which show from May to October. However, the real special feature of this sweet pea variety mixture is that it grows to a height of only about just under 0.5 m, making it ideal for balcony or container plantings.

Perennial species related to sweet pea:

• Perennial pea (Lathyrus latifolius): Grows up to 2 metres high
• Spring pea (Lathyrus vernus): Prefers to grow in partial shade; grows only 30cm tall; important bee pasture in spring
• Black pea (Lathyrus niger): Thrives in a wide variety of habitats; grows in a clump-like manner without climbing

How to plant sweet peas

Depending on the variety, sweet peas can be planted well in different places. For example, low-growing varieties are suitable as a ground cover in borders, beds or as container planting, while larger varieties can act as a handsome screen or for greening fences, facades or other objects.

The right location for sweet peas

As a location is suitable sunny to full sun and warm place. In addition, a somewhat wind-protected location is advantageous so that the somewhat wind-sensitive vetches are not blown over. The soil should be permeable and rich in nutrients. Permeability is very important, as sweet peas prefer to be a little dry than too wet. Furthermore, sweet pea feels comfortable on calcareous soils. To prevent soil fatigue, sweet peas should be sown in a different place each year. However, in suitable locations, sweet pea can also reappear annually by self-seeding – although often more puny over time. In addition to planting directly in the garden, sweet pea can be kept on the balcony and in various planters, such as pots or tubs, and also makes a beautiful sight as a hanging basket plant. Here it should be noted that you take a suitable, nutrient-rich substrate and choose the planter is not too small, because the plant has a fairly lush growth.

Sweet pea support ideas: do they need a trellis?

Of course, if the plants are used as ground cover or in a hanging planter, there is no need for a climbing aid. If the plants grow in beds or containers, a climbing aid for sweet peas is almost essential to enjoy the full splendour of the plants. Most close-meshed structures, such as lattice or wire mesh fences, are suitable for this purpose. You can use almost any material, for example, wooden or bamboo sticks are suitable. Note only that the profile of the vine aid is not thicker than 10 mm in diameter, otherwise the sweet pea will not be able to grip.

When to sow sweet peas

As a rule, sweet peas are not planted but sown directly. Direct sowing of sweet peas starts in March. It is best to sow about 3 seeds per hole at a distance of 15cm. After 1 to 2 weeks the first sprouts appear. When the plant is slightly larger and has formed about 3 pairs of leaves, pinch off the top shoot to stimulate abundant branching.

If you want to use young plants, you can sow seeds indoors from February and plant the plantlets outdoors from the beginning of April at a soil temperature of about 15°C. It should be noted that pre-pulled plants are more sensitive to late frosts.

Alternatively, sowing in late autumn is possible, as the seeds, as long as they have not yet germinated, well withstand frosts.

Tip: By sowing again and again at intervals of about four weeks starting in March, you can enjoy the flower bloom until autumn.

The right care

Since sweet pea realises vigorous growth within a year, the plant needs sufficient water and nutrients. Sweet pea is drought tolerant but should be watered as needed during dry spells. A predominantly organic complete fertiliser, such as our Plantura All Purpose Plant Food, is suitable for fertilising from the start. The high organic content provides a slow release so that sweet pea does not grow soft and unstable due to sudden excess of nutrients. One to two fertilisations per year, in spring and summer, are completely sufficient for mainly organic fertilisers because of their long-term effect.

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Regular cutting of fragrant flowers for bouquets or the like is absolutely beneficial to the growth of the plant to the benefit of many gardening enthusiasts. By removing flowers, sweet pea is stimulated to produce more and more new flowers, showing its full glory for a longer period of time.

Are sweet peas hardy?

Unfortunately, since Lathyrus odoratus is an annual plant, sweet pea is not hardy and dies towards the end of autumn. As described above, overwintering of sweet pea seeds in the soil is possible, which allows the plants to keep in the same place for years by self-seeding. But we have presented you above perennial relatives of sweet pea.

Propagation

So, in order to enjoy the pleasant fragrance and splendour of flowers of sweet pea again next year, you can propagate the plant by seeds. To help germination, you can soak the seed in water overnight, or score it a bit with a sharp knife to make it easier for moisture to get through the hard shell to the embryo inside. These two procedures are conducive to germination but not mandatory. Thus, depending on the procedure and variety, the seeds emerge after about 1 to 2 weeks. If you prefer to grow the plants indoors, a special low-nutrient sowing soil such as our Plantura Organic Herb & Seedling Compost is best to ensure good germination and avoid the emergence of moulds or weeds.

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Tip: Hobby gardeners can easily try themselves to obtain “new varieties” through their own breeding. This is how you proceed:

1. Pick two sweet pea plants to combine.
2. Remove from one of the two parent plants all the open flowers and keep only a few unopened.
3. Now take a look at the unopened flowers: Pull back the outer petals to see the inside of the flower. Open using a needle or tweezers.
4. Inside you will find the centrally located female pistil and the male stamens positioned around it. Remove all the stamens with tweezers. Attention: the pistil should not be injured.
5. From the other plant to be crossed, now cut off a few fully open flowers. Go with the flower to the prepared flowers of the first variety, so that the pollen is transferred.
6. A few weeks later, you can harvest the seeds from your own cross and either store them until spring or sow them directly in the field in late fall.

Can you harvest sweet pea seeds?

Since sweet peas produce abundant flowers when properly cared for, enough seeds can be harvested each fall for the next year. The only important thing for this is to leave enough withered shoots so that the seeds can fully form.

Are sweet peas poisonous?

Sweet pea is classified as toxic. Especially in the seeds accumulate many toxic substances. To protect young children, faded shoots within reach can be removed to prevent seed formation. Plant parts in dogs and cats are not expected to be consumed at a dangerous dose but as the poison develops only in the stomach, harvesting and planting the seeds is harmless.