Clematis (Clematis occidentalis) is an abundantly flowering plant, renowned for its starburst blooms of white, pink, red, purple and indigo. 

Clematis pairs well with both blooming and non-blooming plants. But, not all plants do well in this capacity. Keep reading as I reveal the best Companion Plants for clematis. As well as the worst.

What Is Companion Planting

Companion planting is an effective method of organic gardening that utilizes the natural, synergistic relationships of certain plants for their mutual benefit.

Today, the scientific study of companion planting is just getting started and uncovers more of nature’s secrets every day. However, companion planting has been practised and observations documented for thousands of years by North American Indigenous tribes, the Romans and Greeks of antiquity and Chinese agriculturalists.

By practising companion planting for clematis, you are transported back in time, to an age of holistic and organic gardening, when vining plants thrived and produced without any help from synthetic chemicals or fertilizers.

Clematis plants are typically delicate plants that need a specific environment in order to thrive and abundantly bloom. Once you have their habitat just right, they can be quite low-maintenance and easy to grow.

The right companion plants can help ward off pest attacks and disease with their built-in, anti-fungal properties and sweet fragrance that can disorient detrimental pests, keeping them at bay (this part has been scientifically demonstrated).

At the same time, they can attract the kind of beneficial pollinators, like ladybugs and lacewings that will feast on any pests that aren’t deterred.

When clematis is in full bloom (bloom times depending on the variety), flowers are laden with pollen and nectar to reward those pollinators, as well as the bees, for their protection.

Vital to clematis varieties specifically, companion plants may even improve nutrient and moisture uptake by promoting a more fertile growing medium. Guiding your vining bloomer toward that low-maintenance standing.

In cases where these afflictions aren’t as much of an issue, ornamental companion plants can serve to enhance the beauty of your clematis with complimentary colour and contrast. Contributing to an elegant cohesiveness throughout your garden, be they in pots or in the ground.

What Are the Benefits

As previously mentioned, the effectiveness and reliability of companion planting have thousands of years of anecdotal evidence behind it. As well as more recent scientific findings to back all those anecdotes up. So, what are the benefits, exactly? 

Let’s take a look at what other gardeners, farmers and botanists have discovered.

Weed control

Low-growing, flowering plants, such as mint and marigolds, with sprawling, sub-surface roots can help keep weeds at bay for deep-rooted clematis plants grown in pots. 

The roots of these cover crops take up the space that weeds would otherwise occupy. Without sufficient space to grow, weed seeds may germinate but they will lack the resources necessary to survive.

Pest Control

By planting specimens with specific features together, a well-rounded, organic pest control scheme is put into play. 

Pollen-filled clematis flowers combined with scented herbs will delight our senses. But, aphids, white flies and other harmful insects that are common on clematis will steer clear of the beneficial pollinators that will also be attracted.

Companion plants can effectively take the principles of the natural food chain and use them to protect not only your plants from pest damage but also your soil from toxic pesticide contamination.

Improved Soil Health

Without the need for pesticides, valuable microbes that reside in the soil will begin to thrive and multiply, remaining present to convert nutrients into an easily absorbed form for your plants.

Clematis are notoriously sensitive to overwatering. Thirsty companion plants can relieve this risk by absorbing excess soil moisture that has not properly drained away.

Increased Flower Yields

Certain planting options, like comfrey and borage, have been shown to improve nutrient uptake. To increase flowering on clematis plants, nutrient absorption and metabolism are critical.

Low-growing companion plants will also provide much-needed cover and shade for clematis roots, while not blocking the sunlight needed to trigger bud development.

Consideration When Selecting Companion Plants

When considering plants to pair with your clematis, it makes logical sense to choose ones that thrive in similar, if not the same, growing conditions. 

Regardless of variety, ideal conditions for clematis include:

• Recommendations for hardiness zones 4-9
• Morning sun with afternoon shade (or the reverse) with roots shaded. More sun than shade will trigger increased flowering.
• Free-draining, moist and loamy soil with a slightly alkaline pH.
• Highly fertile soil as clematis is a heavy feeder.
• Outdoor temperatures between 45°F and 80°F
• Tolerant of changing humidity levels within their recommended hardiness zones

Choosing partner plants that share a preference for these environmental features is key to reaping all the benefits we’ve discussed.

The frequency of watering and fertilizing clematis will vary between those grown in pots and those grown in the ground. What type of companion plants you consider should also differ based on where your clematis grows. Yet, there are some that will accommodate both.

For example, clematis pairs well with climbing roses. You can put these in their own container and position them side by side or plant them together in the ground. Both will happily climb up your trellis or pergola. 

Different clematis varieties bloom at different times so you can choose to have your blooming simultaneously or in consecutive stages.

There are many plants that you should not choose as companion plants, which we’ll discuss in more detail in a moment. These would be plants that prefer a growing environment in direct contrast to what clematis plants favour.

Another key consideration is the size of your growing space. Since clematis can group well with small plants and large shrubs, matching the mature size of each plant to your intended growing space is important. 

Lastly, once you’ve achieved a “low-maintenance” clematis by creating ideal growing conditions, you’ll probably want to choose plants that are equally easy to care for.

Best Companion Plants for Clematis

There are over 300 different varieties of clematis. How do you know which one you have and what plants will perform well as companions? 

To help you make the best choice, let’s break down the three categories of clematis, their growing habits and when they bloom.

Group 1: This category includes varieties such as ‘Rosy Pagoda’, ‘Apple Blossom’ and ‘Blue Bird’. All these begin blooming in early spring (late winter in warmer zones) and bud on the previous year’s growth (old wood). 

Group 2: Large-flowering clematis types such as ‘Beauty of Richmond’, ‘Charissima’ and ‘Crimson King’ bloom throughout spring and summer, also on the previous year’s growth. These will bloom a second time if branches are pruned back to a pair of new buds down the stem.

Group 3: ‘Tapestry’, ‘Étoile Rose’ and ‘Minuet’ round out this grouping with blooms that last from summer through fall and bud on the current year’s growth (new wood).

The varying bloom times of each of these groupings allow you more creative control over how your garden grows and when peak blooming occurs.

Now, let’s take a look at the broad range of plants that are suitable as companion plants for clematis.

Vegetables

Shade-grown vegetables like beets, carrots and potatoes are perfect clematis companion plants, as they grow quite productively in partial sun and moist soil. Leafy greens such as Swiss chard, spinach, lettuce and kale also do quite nicely.

Alliums (garlic, onions and chives) have a distinct scent that wards off unwanted pests, slugs and snails and even hungry deer and rabbits. In addition, these produce lovely, ornamental blooms that attract pollinators. All of which contribute to effective pest and weed control.

Herbs and Flowers

We talked about climbing roses. But, ground-cover roses are good choices, as well. They shade clematis roots and provide complementary colour and form.

Herbs, like low-growing basil and catnip thrive in pots and all favour the same growing conditions as clematis while emitting a fragrance that’s unfavourable to pests.

Mint is a fantastic choice because its menthol flavour and scent are the results of biocidal properties that have evolved for the specific purpose of deterring harmful insects.

Bad Companion Plants for Clematis

All this being said, there’s absolutely nothing wrong with going for form over function and pairing your clematis with plants of similar needs simply because they look beautiful together. 

Complementary gardening has been a staple of good landscape design for decades. For example, Clematis and hydrangeas put on a spectacular show. Weaving them through mature elderberry looks equally stunning if you have the room.

But, choose plants that serve both purposes and these will become the true workhorses of your garden. Basically doing all the work for you.

However, choose the wrong companion plants for clematis and it could all go terribly wrong. So, what are those?

For starters, since clematis require sufficient sunlight in order to bloom, you wouldn’t want to position your clematis under a tall, sunlight-blocking tree. 

While shade trees make fantastic companion plantings for other plant types, they aren’t great choices, in this instance. This applies to those grown in the ground and in pots.

Drought-tolerant plants are also non-starters as these will suffer in the consistently moist soil that a clematis prefers. 

For example, woody herbs like rosemary, thyme, sage and marjoram are all low-growing, pretty plants that would nicely shade clematis roots, in pots. Yet, they favour full sun and dry, infrequently watered soil.

If you’re considering larger shrubs as companion plants for ground-planted clematis, bougainvillaea, lilacs, butterfly bush and barberry varieties also fall under the category of drought-tolerant and would not thrive in a moist environment.

Another seldom-discussed point is that some plants release allelopathic chemicals into the soil that may be beneficial or detrimental when planted with sensitive clematis.

While preferring somewhat moist soil, deep shade plants like ferns and hostas, won’t do well in the kind of direct, partial sunlight that clematis plants require.

Finally, as a general rule, it’s always best to pair your clematis with plants that are recommended for your hardiness zone. Plants can sometimes be found on the shelves of nurseries and garden centres that don’t necessarily thrive where you live. Be sure to read the labels of plants that catch your eye to determine compatibility. These labels will also list the care requirements of each plant, which will help you match them to the needs of your beautiful, and sometimes finicky, clematis.

If you have enjoyed this article, here’s a link to Companion Plants for Japanese Maple that you may find interesting.

References

• Montana State University – The Science of Companion Planting in the Garden
• The National Gardening Association – Roses and Clematis
• The University of Illinois Extension – ALLELOPATHY: A Plant’s Chemical Warfare