Rampion Bellflower
Campanula rapunculus, or the Rampion bellflower, comes from the Campanulaceae plant family.
At one stage, this lovely plant was grown as a food source, where its foliage was treated like spinach, and its tuberous roots like radishes.
If the scientific name looks vaguely familiar, it’s because it’s the origin of Rapunzel, the fairy tale character.
This lovely perennial produces light purple flowers with a silvery, bluish tinge in some lights, and will grow in either partial shade or full sunlight, whatever you happen to have.
This plant will thrive in USDA zones 3 through to 9, making it a versatile planting choice.
Rat Tail Cactus
While not a flower, the rat tail cactus should be on your must-grow list if you like unusual plants.
Aporocactus flagelliformis, as the name suggests, produces thick, succulent leaves with a scale-like texture, resembling rat tails.
It’s very easy to grow, and produces seas of purple-pink flowers once mature.
It will grow well in zones 10 to 11, but you can also grow it as a houseplant in a tall container or hanging basket.
This particular cactus will reach a maximum height of 60cm tall, and this may be much smaller if you’re growing this striking plant indoors.
Rebutia Cactus
Plants belonging to the Rebutia genus hail from northern parts of Argentina, as well as the high Andes in Bolivia.
You can recognize a rebutia cactus by its compact form, plethora of spines covering the ball-shaped cactus, as well as the starry, pink, red, or white flowers, featuring yellow anthers.
If you don’t live in USDA zones 10 or 11, you’ll need to grow this cactus as a houseplant, where it will need the most sunlight you can give it.
Red Buttons Opuntia Cactus
Also known as the prickly pear cactus, Opuntia Quitensis, or the red buttons opuntia, this is a striking species worthy of any cacti collection (see also Opuntia Cactus Care Guide).
It produces tiny, bright red flowers which sit directly on top of the succulent leaves.
This plant ranges from 15-30cm tall as it matures, and will withstand temperatures as low as 30°F (or -1°C).
This cactus is perfect for gardens which get very little rainfall and a lot of hot, dry weather.
One thing to note is that the prickly pear cactus is covered in long, sharp spines, so don’t plant it near high-traffic areas, or consider another plant entirely if you have pets or children.
There are two things that this plant absolutely requires in order to do well: a bright, sunny position for as long as possible, and well-draining soil.
Red Campion
Available in perennial or biennial forms, this is a fairly tall plant, also known as Silene dioica.
Red campion flowers in mid-spring, usually when bluebells have finished for the season.
You may also see it labeled as the adder’s flower, the cuckoo flower, or even Robin Hood. As you might guess, this flower has some symbolism behind it.
In folklore, it’s believed that red campion flowers help to protect the precious hives of bees and their honey.
Red campion plants are handsome, with hairy foliage and pinkish red flowers.
In their natural habitat, they grow in dappled shade beneath woodland or shrubs, as well as by roadsides and in fields.
It also helps that red campion attracts many beneficial insects into your garden, helping to boost its overall health and keep pest numbers down.
Red Hot Poker
Kniphofia, or the red hot poker, is a great perennial plant which makes a statement in any garden.
It flowers from spring all the way through to mid-fall if the weather allows, in warm shades of yellow, red, orange, pink, and white, usually a combination of two.
The red hot poker is a very easy plant to look after, and depending on what variety you go for, they may be hardy or only half-hardy.
Some cultivars are capable of reaching over 6 feet tall, while others will stay compact at around 20cm.
Give red hot pokers a fully sunny position, as a border or mixed bed plant, and well-draining soil, and they should flower for years to come.
Smaller cultivars are also suitable for containers or compact, mixed borders.
Red Torch Cactus
Perfect for xeriscaping, the red torch cactus produces dramatic red flowers, atop spiky columns.
Also known as Echinopsis huascha, this is a great plant to add more texture or interest into rockeries or well-draining beds.
Just make sure you plant it away from paths or areas which you’re likely to brush past the plant, as the spikes cover the surface of each column.
This plant loves as much sun as you can give it, in well-draining soil.
Depending on the growing conditions, the red torch cactus can get to between 60cm and 91cm high, adding architectural form and color into your garden.
Red Twig Dogwood
Cornus sericea, the red osier dogwood, Tatarian dogwood, or the red twig dogwood is an excellent choice for a low-maintenance garden.
These shrubs love damp, fertile soil, and can reach between 6 and 10 feet high, spreading anywhere between 8 and 12 feet wide.
Their brilliant red branches are attractive in any garden, and it also helps that the red twig dogwood produces seas of white flowers during spring.
The red twig dogwood will grow in either partial sunlight or a position of full sun, but make sure you leave enough room for adequate airflow around the plant, in order to prevent disease.
This shrub will thrive in USDA zones 3 through to 8, able to withstand the colder temperatures in these regions without a problem.
This plant really comes into its own during fall and winter, when it loses its leaves and the bare stems get a chance to show off their crimson hues.
Red Valerian
Centranthus ruber, otherwise known as fox’s brush, German lilac, pretty Betsy, kiss-me-quick, or Jupiter’s beard is a colorful perennial.
This plant is famed for its ability to bring in more pollinators into your garden, thanks to its fragrant blooms which appear from the last weeks of spring well into fall.
It needs well-draining soil and full sunlight, but it will tolerate exposed areas without any issues.
Redvein Enkianthus
Enkianthus campanulatus, or the Redvein Enkianthus is another ornamental shrub which will bring a wealth of color into your garden.
As part of the heath family, it should come as no surprise that this plant produces clusters of tiny, bell-shaped flowers in shades of yellow and pink, appearing from spring into summer.
This plant hails from the forests of Japan, where it’s known as furin-tsutsuji.
It will grow to an average height of 8 feet tall. Some varieties can reach larger heights, at a maximum of 15 feet.
It’s not a demanding plant, doing well in partial shade or full sunlight, though it will be healthier in dappled shade, mimicking its natural environment.
It does best in damp, well-draining soil which is packed full of nutrients, with a pH at 6 or below.
Regal Geranium
Arguably one of the most beautiful pelargoniums available is Pelargonium x domesticum, or the regal geranium.
It’s the resulting cross of Pelargonium cucullatum, and Pelargonium grandiflorum, and there are many color combinations to choose from.
The flowers are usually bi-colored, featuring shades of purple, pink, white, or red.
The regal geranium is a perennial plant in USDA zones 10 and 11, and you can either grow it as a bedding plant outside these zones, or overwinter it indoors.
The regal geranium can reach 3 feet tall once it is mature, provided that you give it full sunlight and well-draining soil.
Reticulated Iris
Iris reticulata, is a showy plant that produces vivid blue flowers with hints of white and yellow.
It’s a perfect perennial if you find that most types of iris are too large for you, as Iris reticulata will reach between 7 and 15cm high once mature, making it perfect for container gardens, the front of borders, or smaller spaces overall.
You can grow it in full sunlight or dappled shade, and it will weather both deer and dry spells without much problem.
Rex Begonia
One of the most ornate foliage plants you can get, the rex begonia, or Begonia rex-cultorum makes a statement in both outdoor gardens and inside as a houseplant.
These perennials like their soil to be on the moist and acidic side, as long as it drains well.
The variegated leaves come in many forms and colors, including silver, green, red, pink, and in some lights, even blue.
Depending on the variety, rex begonias usually reach between 30 and 45cm tall, spreading about the same.
The bright veining on the foliage of this plant contrasts well against any plant you choose to put it with.
However, it does need some shade to survive, so make sure you provide it with plenty of indirect light.
It’s worth knowing that this plant is toxic to animals, no matter which variety you go for, so make sure to keep it away from pets and children.
Rhipsalis Neves Armondii
Perfect for hanging baskets, this succulent produces pencil-like foliage which spills over the edges of the pot, trailing towards the floor.
This plant likes warm temperatures, so if you don’t live in one of the USDA zones 10a through to 11b, you’ll need to grow it as a houseplant.
It also requires good drainage, so water your succulent carefully, and make sure to provide it with well-draining compost.
One thing you will need to avoid with Rhipsalis Neves Armondii is direct sunlight. While it is a succulent plant, and therefore a lover of bright light, direct sunlight can cause scorching.
It will withstand temperatures down to 30°F (or -1.1°C), so you can grow it outside and overwinter it indoors if you live somewhere that gets harsh winters.
This succulent also produces showy white flowers, which are followed by purple fruit.
Rhododendron
A cornerstone of gardens across the world, gardens would not be the same without the rhododendron.
One thing that rhododendrons absolutely need is a soil pH between 4.5 and 5.5.
If this isn’t possible in your garden, there are smaller cultivars available, which are suitable for growing in containers.
Growing plants in containers allows you to manipulate the pH, soil type, and drainage more easily than trying to modify the earth in your garden.
Rhododendrons will grow in either dappled shade or full sunlight, and provide form and color, with solid, evergreen foliage, and huge flowers which grow in clusters.
The blooms themselves come in a wide range of shades of red, pink, white, yellow, and purple.
These evergreen shrubs also attract plenty of wildlife such as bees, butterflies, and birds into your garden.
Robin’s Plantain
Erigeron pulchellus, or Robin’s plantain comes from the daisy plant family, and you can easily spot the resemblance in the flowers, which have large, sunshine-yellow discs in the center.
It hails from many parts of North America. This plant is a perennial, which can reach a maximum of 2 feet tall.
It’s worth knowing that Robin’s Plantain spreads easily thanks to its rhizomes, so make sure you give it plenty of room to grow.
Each plant can flower profusely, producing anywhere between a single bloom to 9 flower heads per stem, providing a sea of color in your garden in shades of white, pink, or lilac.
Robin’s Plantain will survive in very dry or damp soil without any problems, as long as it is grown in a sunny position.
It’s hardy in USDA zones 3 through to 8.
Rocket Larkspur
Consolida ajacis, rocket larkspur, or doubtful knight’s spur, is an annual which will inject plenty of color into the beds and borders in your garden.
It’s part of the ranunculus or buttercup plant family, and looks similar to a delphinium, but the flowers are much larger, and aren’t as tightly packed.
Rocket larkspur flowers come in lilac, each flower capable of reaching 2 inches in diameter.
It prefers full sunlight in damp, loamy soil where possible. The common name, rocket larkspur, refers to its vigorous growth, and how it can spring up, seemingly out of nowhere.
While this plant hails from the Mediterranean, it is grown all over the world as an ornamental plant, naturalizing itself in a few areas.
The flowers are a favorite of bees, especially bumblebees.
This is not a suitable plant for your garden if you have pets or children, even as visitors.
The plant, especially the seeds, contains dangerous alkaloids and can cause serious harm if ingested.
Rocky Mountain Iris
If you like irises in paler shades, the rocky mountain iris, or Iris missouriensis, might be the next plant on your list.
It likes damp or even boggy soil, making it a good contender for areas of your garden that other plants would not tolerate.
It’s very easy to grow, making it perfect for beginners or seasoned gardeners alike.
The rocky mountain iris produces pale blue flowers with flashes of yellow on the fall petals, and streaks of dark blue.
This plant will also tolerate soil with a pH between 6 and 8, and either full sunlight or dappled shade.
Rodgersia
Rodgersia aesculifolia, the chestnut-leaved rodgersia, features large, deeply-veined leaves, and throws out a multitude of airy, white, pink, or yellow flowers in summer.
This is a woodland plant, so it needs at least some shade for most of the day. It can even thrive in full shade, and it will offset well against other shade-loving plants such as hostas and ferns.
You can plant it in full sunlight if you prefer, but the soil will need to be damp at all times in order for the plant to stand that much light.
It can reach anywhere between 4 and 6 feet tall, spreading to a maximum of 5 feet, depending on the growing conditions.
It’s fairly slow-growing, so you won’t see its eventual size until 2 or even 5 years after planting, depending on the age of the plant when you get it.
This makes it easy to maintain, and it helps that it is an award winner, having received the AGM from the Royal Horticultural Society.
It is worth mentioning that this plant will not tolerate exposed areas very well, so keep the plant in a sheltered position, away from high winds.
Roof Iris
Iris tectorum, the wall iris, or the roof iris, is a type of bearded iris which doesn’t have the distinct ‘hair’ on the fall petals of the flower.
This striking plant hails from Burma, Korea, and China, and it’s grown across the world for its ornamental value.
It’s a hardy perennial in USDA zones 4 through to 9, and will grow happily in either full sunlight or partial shade, whichever you happen to have.
Like most forms of iris, the roof iris is robust against deer, and also makes a great cut flower, with its striking colors and long-lasting flowers.
It will tolerate soil which has a pH between 6.1 and 7.8, and depending on the variety you go for, it may reach as tall as 45cm high.
Rose Mallow
Part of the mallow plant family, along with hollyhocks, okra, and cotton, the rose mallow is a very robust plant, providing
Hibiscus moscheutos, the common rose mallow, or crimson eyed rose mallow likes wet areas, as it’s commonly found in wetland in the wild of the eastern US.
Depending on the variety, flowers may be white, or various shades of pink, usually featuring a crimson or dark brown ‘eye’ in the center of each flower.
Many cultivars have been created, as the rose mallow is easy to hybridize, meaning more colors and different forms are now widely available.
If you are lucky enough to live somewhere that has hummingbirds, you may be interested to know that the rose mallow contains a lot of nectar, which draws in these fantastic birds and other pollinators.
Hardy in zones 5 through to 9, the rose mallow is perfect for mixed beds or even container gardening, provided that you give it enough moisture.
It will tolerate soil with a pH between 6.8 and 7.7, and depending on the variety, it can reach between 3 and 5 feet high.
Rose Of Sharon
Hibiscus syriacus, the common hibiscus, or the rose of Sharon is also a member of the mallow plant family.
It comes from southern parts of China, and its ease of care means that it’s grown across the world as a valued ornamental.
The rose of Sharon introduces tropical vibes into your garden, with its large, dramatic flowers, in shades of pink, purple, red, and white.
You may need to prune it occasionally, but this is by far the most maintenance you’ll have to do with this plant.
It will range from 9 to 12 feet high when mature, and can be trained to screen your garden, allowing for attractive privacy borders.
You may also need to divide the plants every few years, as they will fill any available space.
If you don’t have room for more common hibiscus in your garden, you can also plant them up in containers and give them to friends, or do a plant trade with people in your area to get a plant that you do want.
Roses
This is simply one of those plants that we couldn’t leave off the list.
There are so many varieties out there, from old favorites like the damask rose, to newer hybrids framed for their number of petals, disease resistance, or delicious fragrance.
They’re all beautiful, and you can get them in different growth habits, such as climbing roses, rambling roses, shrub roses, and miniature roses (see also Plants Suitable For Narrow Pots).
They also work well as border plants or even to add extra security around your property, if you go for a very thorny variety!
Some types of rose are more suitable to different spaces than others (see also Rose Grow Guide). For example, it’s not a good idea to choose a vigorous, rambling rose (see also Climbing Vs Rambling Roses) for a container garden, as it needs support, and some cultivars easily reach 40 feet high.
Depending on the type of rose you go for, they may prefer dappled shade, or full sunlight.
Some will require staking or constant support, which makes them good plants for filling trellises, walls, and obelisks with life and color.
Rosemary
You’re probably familiar with rosemary in one way or another, but you might not be aware that the plant produces seas of gorgeous baby blue or white flowers.
Rosemary does a lot for your garden. Not only can you use the leaves as a culinary herb, as well as topical and medicinal applications such as a natural mouthwash, but the plant attracts many pollinators.
It also withstands deer, and the whole plant is fragrant.
Rosmarinus officinialis, is a perennial herb which likes soil to be on the dry side, with a pH between 6.6 and 8.5.
If you live outside USDA zones 8 through to 10, you may have to grow this plant as an annual, but you can also overwinter it or grow it exclusively indoors.
If you do decide to grow it indoors, it’s worth knowing that the plant won’t flower inside.
This versatile herb needs full sunlight in order to thrive, for as long as possible. It also helps that rosemary is quite drought tolerant, and prefers nutrient-poor, sandy soil.
