There are so many wonderful flowers out there, it may seem impossible to narrow down which ones deserve a place in your garden! There are annuals, perennials, biennials, high-maintenance plants, easy-to-grow plants, drought-tolerant plants, the list goes on and on and on!
In the long list of flowering plants, shrubs, trees, and vines, flowers that begin with K might seem few and far between. However, there are plenty of beautiful kinds of flowers whose names start with this letter!
This short but inspired list of delightful plants will hopefully help you make an informed choice of what will fit in with the rest of your outdoor space, and match your gardening style.
#1 Kaffir Lily
Kaffir lilies, also known as bush lilies, or clivia spp., are a small genus of only 6 described species that are native to South Africa. These plants are frost-tender perennials that will need overwintering in cooler climates. Luckily, these plants are well-suited for container growing, so can easily be moved indoors or into a frost-free building like a garage over winter! Kaffir lilies are shade-loving plants so they should never be exposed to direct sunlight, except in winter when light levels are naturally low.
The most well-known of the group is C. miniata, which is also called the September lily. They grow as tall as 2 feet high, and are clump-forming, spreading to a width of 3 feet given the chance. Like other kaffir lilies, C. miniata flowers are showy, funnel-shaped, and grow in attractive, vividly colored clusters! Their flowers come in shades of red, yellow, and orange, and contrast nicely with their dark green foliage.
#2 Kahili Ginger
Kahili ginger is a popular ornamental flower that will demand attention in any garden! They have exotic cylindrical spikes that can grow as tall as 1.5-2 feet and are packed with up to 50 fragrant, lemon-yellow flowers that have a single, prominent, reddish-orange stamen. They are herbaceous perennials with foliage typical of the ginger family, Zingiberaceae.
These plants can be found in the wild growing inside the tropical forests of Nepal, Bhutan, northern India, and the eastern Himalayas. Their unique flowers make them a favorite for tropical gardens, especially in areas like Hawaii and the Caribbean where they thrive! Plant them as garden specimens, or use them to add height to sunny or partially shaded borders.
These amazing flowers belong to the genus Kalanchoe, and are a group of around 120 species of succulents! Most are herbaceous perennials, however, some are shrubs and annuals. They are tropical plants, native to parts of Africa and Madagascar. Many of them are well-loved houseplants, but under the right conditions and with some extra care over winter, they can be grown as outdoor container plants!
The most popular Kalanchoes are known as florist kalanchoes and are derived from K. blossfeldiana. They usually have dark green, thick waxy leaves, and beautiful flowers that come in vivid hues of white, pink, red, yellow, or orange. Indoor plants need full sunlight, but if they are being brought outdoors for the summer, morning sun is best, as the strong afternoon rays may burn them.
Kalmias are evergreen shrubs that belong to the heath family, Ericaceae. There are 7 species in the genus Kalmia, all of which are found either in North America or the West Indies, except one which can be widely found within the Northern Hemisphere. Their flowers look unassuming from afar, but a closer inspection will reveal their incredible beauty!
Their showy flowers are bowl-shaped and grow either in terminal clusters, or clusters growing along the leaf axil. The flowers come in delightful shades of pink, purple, or white, with their anthers tucked into pockets on the surface of the petals. Depending on species, they can grow between 2 and 6 feet tall, making them fantastic as specimen shrubs or hedges. Plant them alongside azaleas or rhododendrons for a stunning floral display!
Known locally in the Philippines as kapa-kapa, the showy medinilla or Medinilla magnifica is a tropical evergreen shrub native to the Philippine islands. They are epiphytic and will grow up to 4 feet high in their preferred habitat which is inside the pockets of trees or ground clearings in the rainforest. They need warm and humid climates to be grown successfully, and outside of USDA zones 10-11, these plants can be grown in pots but will need overwintering in a warm room or greenhouse.
They have incredible flowers which are small, and come in shades of pink to red, and grow in drooping panicles hooded by pink modified leaf bracts. These panicles can grow up to 18 inches long, giving a truly unique display! Kapa-kapas have lovely dark green foliage that contrasts nicely with their showy flowers. In tropical climates, grow them along borders, and in milder climates, use them for exotic patios in the summer and as houseplants in the winter.
#6 King’s Spear
King’s spear is a clump-forming perennial with whimsical flowers. They have a wide native range, from Northern Africa to Western Asia, to southeastern Europe. Other names for these plants are Jacob’s rod and asphodel. They look fantastic planted in large groups along the borders of cottage-style or wild gardens! When dried, their flowers and fruits are popular for dried flower arrangements.
These plants grow as large as 4 feet tall and 2 feet wide. From May to June, they produce long, densely packed, cylindrical racemes adorned with fragrant yellow flowers. After the blooming period, their flowers transform into green seed pods that mature to brown. Their grass-like silvery green leaves simply add to their attraction! In milder climates, give them a good mulching over winter for some added protection from the cold.
Kiss-me-over-the-garden-gate is a lovely annual wildflower that will add some flair to cottage-style or pollinator gardens! Sometimes referred to as prince’s feather or Persicaria orientalis, these plants have unusual flowers that will attract hummingbirds and other pollinators into the garden. These plants are easy to grow and will self-seed under optimum conditions. They can grow as tall as 7 feet and prefer fun sun to partial shade.
These plants have a long blooming season from summer through to fall, and have beautiful blooms that also make good cut flowers or indoor displays! Their deep rose flowers are clustered together on densely packed flower spikes 3-4 inches long. These spikes hang gracefully down from slender arching stems.
#8 Knautia Flowers
Knautias or widow flowers are a group of annual and perennial wildflowers of the genus Knautia. Their native range is in central Europe, and the flowers of this group have pretty pincushion forms. They are clump-forming and can have a rather informal appearance, lending them particularly to meadow, wildflower, or cottage-style gardens! Grow them amongst other wildflowers, or en masse along borders.
K. macedonica is a common favorite of the group. It blooms from mid-summer to early fall, producing domed pincushion flowers that are 1.5 inches across and a rich purple-red! Knautia plants do best in cool summer climates as they may wilt on hot summer days. They make lovely cut flowers, but are also lovely as dried flowers!
#9 Knock Out Roses
Knock Out roses are a rose shrub cultivar that has become a firm favorite in the gardening world since their introduction into the mainstream market in 2000. They were first developed by a rose breeder from Wisconsin in 1989, and are prized for their vividly colored flowers, but best of all, unlike other roses, they are relatively easy to grow! Knock Out roses have an extremely long blooming period, and in some areas, they may flower almost year-round.
Since their introduction, many new varieties have been bred, leading to dwarf varieties perfect for containers, different colors such as pink, red, yellow, and white, and even double-flowered types! Knock Out roses are drought and disease resistant, making them ideal for beginner gardeners who love roses but are intimidated by their upkeep!
Kolkwitzia amabilis, known as the beauty bush or simply as kolkwitzia, is a beautiful ornamental shrub native to Eastern China. They are extremely popular among gardeners as hedges or border shrubs as they can grow as tall and wide as 10 feet! Their flowers appear en masse in mid-spring and will do a good job of attracting hummingbirds into the area.
Their bell-shaped pink flowers have yellow throats and grow in attractive clusters amongst their dark green foliage. Kolkwitzias will grow well in average soils and may need some pruning to keep them in tip-top shape! Their flowers are reportedly the most vivid under filtered sun or partial shade conditions, so shady borders are the perfect spot for them!
Kunzeas are a group of flowering evergreen shrubs or small trees that are originally found in Australia. They are characterized by their unusual flowers that look like fuzzy little clusters due to their bottlebrush appearance and conspicuous stamens. Some members of the group, particularly K. ambigua, have been cultivated as garden ornamentals that are highly attractive to birds and other pollinators!
K. ambigua, otherwise known as the tick bush, has an upright growth habit and can reach heights of up to 16 feet! It has small narrow foliage, and in spring produces masses of small, honey-scented white flowers that grow in clusters laterally along its branches. They grow well in containers and look stunning in patio, coastal, and Mediterranean garden schemes!
#12 Kyushu Meadow Rue
Kyushu Meadow Rue, or Thalictrum kiusianum, is a delightful little perennial plant that is originally found in Japan and Korea. They are low growing, reaching a maximum of 6 inches but have a spread of 1.5 feet making them a top choice for ground cover! Over summer, their tiny, starry, pale purple-pink flowers appear in fluffy clusters rising above the foliage.
These pretty plants will grow in full sun to partial shade but will require consistent moisture under sunny conditions. They do extremely well in moist, shaded areas, making them the perfect candidate for woodland edging, and darker areas of rock gardens!