20 Best Knock Out Rose Companion Plants, and How to Choose

I’ve written an extensive list of the best companion plants for roses, and many of those apply here. But as knock out® roses are slightly different, I’ve selected the best knock out rose companion plants below.

Knock Out rose companion plants include lavender, pansies, Impatiens, and marigolds. Or cottage garden plants like poppies and Larkspurs. Knock out rose companion plants need to be relatively small, compact, enjoy similar soil and sun conditions, and not compete heavily for resources.

For those perhaps wondering what knock out® roses are, and how they differ from other types and categories of roses.

Here’s a quick rundown of what a knock out® rose is. Then we’ll get into the knock out rose companion plants.

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What are knock out roses?

Knock out® roses are a type of rose that was developed in the late 20th century. They’re known for their ease of care, as they’re disease-resistant and require very little pruning.

What sets knock out® roses apart from other types of roses is their size.

They’re considered to be a dwarf variety and grow to around 3 feet tall and 3 feet wide.

This means they stay relatively small, making them perfect for gardens where space is limited.

Knock out® roses are also known for their continuous blooming. Most varieties will bloom from early spring all the way through to the first frost.

This means you’ll have beautiful blooms in your garden for a good portion of the year.

If you’re looking for a complete list of rose companions, then check my best companion plants for roses post here.

Best knock out rose companion plants

Now that you know a bit about what knock out® roses are, let’s talk about some of the best companion plants for them.

These companion plants apply to just about all knock out® roses, be they sunny knock out roses, double knock out roses, petit knock out roses, pink, or yellow knock out roses.

But check the information below along with your regional growing zone to check they’re a good match.

And check the heights if you’re layering up your beds and borders.

Here’s a quick summary table before you read up more about each plant.

Companion	Height	Wid	Soil	Sun
Impatiens	12″	12″	Drained	Full sun
Pansies	6-8″	6-8″	Drained	Full sun
Lavender	1-2′	1-2′	Various	Full or Partial
Marigolds	1-2′	1-2′	Drained	Full
Lobelia	6-12″	12″	Drained	Full
Dianthus	6-12″	12-18″	Drained	Full
Poppies	2-3′	2-3′	Drained	Full
Larkspurs	3-4′	2-3′	Drained	Full
Pinks	12-18″	12″	Drained	Full
Baby’s Breath	12″	12″	Tolerant	Full
Creeping Phlox	6″	12″	Tolerant	Full
Petunias	12″	18″	Drained	Full
Verbena	6″	12″	Tolerant	Full
Asters	2-3′	2-3′	Drained	Full
Dwarf Gardenias	2-3′	2-3′	Drained	Partial
Lantana	2-3′	2-3′	Drained	Full
Salvias	Var	var	Tolerant	Full
Pentas	2-3′	2-3′	Drained	Full
Lamb’s Ear	12-18″	12-18″	Drained	Full
Nasturtiums	3′	3′	Tolerant	Full or Partial
Herbs too, see below

Impatiens

One of the best knock out rose companion plants is impatiens. Impatiens are annual flowers that bloom in a variety of colors, including pink, red, purple, and white.

They grow to be around 12 inches tall and 12 inches wide, making them the perfect size to plant next to your knock out® roses.

Impatiens also enjoy full sun and well-drained soil, making them easy to care for.

Pansies

Pansies are another great option for knock out rose companion plants. Pansies come in a wide range of colors, including yellow, purple, red, and white.

They grow to be around 6 inches tall and 6 inches wide, making them the perfect size to plant next to your knock out roses.

Pansies also enjoy a lot of sunshine, along with well-drained soil, so they’ll be low maintenance along with your knock out roses.

Lavender

Lavender is a perfect companion plant for knock out roses. Lavender is an herb that comes in a variety of colors, including purple, blue, and white.

They grow to be around 1 – 2 feet tall and 1 – 2 feet wide but should spread, making them a great size to plant next to your knock out roses.

Lavender also thrives in full sun and won’t compete for resources. And they help keep pests away.

Marigolds

Marigolds are another great option for knock out rose companion plants – or any roses for that matter.

Marigolds come in a variety of colors, including yellow, orange, and red. They grow to be around 1-2 feet tall and 1-2 feet wide, making them the perfect size to plant next to your knock out roses.

Marigolds also enjoy full sun and well-drained soil. In fact, they can really tolerate most types of soil. they’re also great for keeping pests at bay.

Lobelia

Lobelia is a great companion plant for knock out roses. Lobelia is an annual flower that blooms in a variety of colors, including blue, purple, and pink.

They grow to be around 6 inches tall and 12 inches wide, making them a great size to plant next to your knock out roses. Lobelia also enjoys full sun and likes well-drained soil, making them easy to care for.

Dianthus

Dianthus is another great companion plant for knock out roses. Dianthus are also annual flowers that come in a variety of colors, including pink, red, and white.

They grow to be around 6-12 inches tall and 12-18 inches wide, making them a perfect size to plant next to your knock out roses.

Dianthus also enjoys full sun and well-drained soil.

Here are more plants that companion well with knock out roses:

Poppies

Poppies are annual flowers that come in a variety of colors, including red, orange, and yellow.

They grow to be around 2-3 feet tall and 2-3 feet wide, making them a great size to plant next to your knock out roses. Poppies also love lots of sunshine and well-drained soil.

I would also associate poppies with rambling roses and types of floribunda roses in a wild or cottage garden setting, so consider that when looking at your overall garden design.

TIP: Poppies are great for a cottage garden look. So if you are looking for a more natural look to your garden, then you might also want to consider more cottage garden favorites like Larkspurs to companion with your knock out roses. https://www.naturehills.com/search/?q=poppy

Larkspurs (Delphinium)

Larkspurs, or Delphinium to give it the broader name, are straight, spiky flowers that come in a variety of colors, including blue, purple, and pink. They grow to be around 3-4 feet tall and 2-3 feet wide.

They will match the height of your knock out roses but can mix well with them to create a lovely color array.

Larkspurs love full sun and well-drained soil, making them another great option to plant next to your knock out roses.

They also don’t require a lot of water, so they are perfect for those who want plants to be a little more drought-tolerant in their garden.

Pinks (Dianthus)

Pinks are another old-fashioned favorite that works well as companion plants for knock out roses.

They have small, delicate flowers that come in shades of pink, red, and white.

They’ll grow to be around 12-18 inches tall and 12 inches wide, so they are perfect for filling in gaps in your garden.

Pinks also enjoy full sun and well-drained soil. They are drought tolerant and make a great addition to any garden.

Baby’s Breath

Baby’s breath is a small, delicate flower that is often used in bouquets and other floral arrangements.

It has small, white flowers that grow in clusters. Baby’s breath grows to be around 12 inches tall and 12 inches wide.

Baby’s breath enjoys full sun and well-drained soil. It is drought tolerant and makes a great addition to any garden.

Creeping Phlox

Creeping phlox is a low-growing, evergreen plant that has small, pink, or purple flowers. It grows to be around 6 inches tall and 12 inches wide.

Creeping phlox enjoys full sun and well-drained soil. It is drought tolerant and makes a great addition to any garden.

Petunias

Petunias are annual flowering plants that come in a variety of colors including pink, purple, red, and white.

They grow to be around 12 inches tall and 18 inches wide.

Petunias enjoy full sun and well-drained soil. They are drought tolerant and make a great addition to any garden.

Verbena

Verbena is a perennial flowering plant that has small, purple flowers. It grows to be around 6 inches tall and 12 inches wide.

Verbena enjoys full sun and well-drained soil. It is drought tolerant and makes a great addition to any garden.

Asters

Asters are another great annual flower to plant next to knock out roses. They come in a variety of colors, including pink, purple, and white.

Asters grow to be around 2-3 feet tall and 2-3 feet wide, making them the perfect size for underplanting knock out roses.

They also thrive in full sunshine, don’t compete for water and other nutrients, and grow well in well-drained soil.

Dwarf gardenias

Dwarf gardenias are a perfect knock out® rose companion plant for knock out® roses. They have a beautiful, sweet fragrance and come in white or pink flowers.

Dwarf gardenias grow to be around 2-3 feet tall and 2-3 feet wide, making them the perfect size to plant next to your knock out® roses.

They do however prefer partial shade and well-drained soil and require more water than asters. So be aware of this when planting.

TIP: Knock out® roses, like most other roses, like a lot of room to both spread their canes outward and room for roots to spread out. So smaller plants work fine underplanted with roses, but larger plants like asters and dwarf gardenias should be spaced further away to allow all plants enough space.

Lantana

Lantana is another great companion plant for knock out roses. It’s a heat-loving, drought-tolerant plant that comes in a variety of colors including yellow, pink, purple, and orange.

Lantanas grow to be around 2-3 feet tall and 2-4 feet wide, making them the perfect size to plant under or around your knock out roses.

Salvia (garden sage)

Salvias are a group of plants that come in many different colors, shapes, and sizes.

Some salvias are annuals while others are perennials, but they all share one trait – they’re heat-loving and drought-tolerant.

There are many different varieties of salvia, so you’re sure to find one that compliments the color of your knock out roses.

Pentas

Pentas (or Egyptian Star Flower) is another heat-loving, drought-tolerant plant that comes in a variety of colors including pink, purple, red, and white.

They grow to be around 2-3 feet tall and wide, making them the perfect size to plant under or

Lambs’ Ear

Lambs’ ear is a soft, fuzzy plant that’s often used as a ground cover. It has silvery-green leaves and blooms in the spring with small, lavender flowers.

Despite their delicate appearance, lambs’ ear is actually quite tough and can tolerate full sun and even poor soil conditions.

Nasturtiums

Nasturtiums are cheery annual plants that are easy to grow and thrive in poor soil.

They have round, green leaves and brightly colored flowers that come in shades of orange, red, yellow, and pink.

Nasturtiums grow up to 3 feet tall and wide. They prefer full sun but can also tolerate partial shade.

Herbs as knock out rose companion plants

I’ve mentioned lavender already, but here are some other herbs that you can use as knock out rose companion plants.

Catmint – Catmint is a member of the mint family and has pretty blue flowers. It’s a drought-tolerant plant that does well in full sun.

Oregano – Oregano is a perennial herb with small, white flowers. It’s tolerant of dry conditions and grows best in full sun.

Rosemary – Rosemary is an evergreen herb with small, blue flowers. It grows best in full sun and can tolerate dry conditions.

Sage – Sage is another perennial herb that does well in full sun. It has purple or white flowers and is tolerant of dry conditions.

Thyme – Thyme is a perennial herb with tiny, pink, or white flowers. It prefers full sun and can tolerate dry conditions.

These herbs are all small in size, so they’ll fit nicely into any gaps in your planting beds. They also enjoy full sun and well-drained soil, making them ideal companions for knock out roses.

Herbs offer the added bonus of being edible, so you can snip a few sprigs to add to your dinner plate.

Or, if you’re feeling extra fancy, try making a rosemary-infused cocktail or a thyme-infused vinegar.

Either way, you can’t go wrong with these versatile and tough plants.

Knock out rose companion plants ~ More roses help! 🌹

What a choice! I hope this has helped you find some suitable knock out rose companion plants that are as easy to care for as your knock out® roses!

Not all of them will work in every scenario in your garden, so be sure to try some and see how it goes.

Or consider other options. Just experiment with plants that are small, drought-tolerant, like similar soil conditions, and enjoy lots of sun for best results.