There is a lot of available information online when it comes to good Dahlias companions, however, there is very little information about what kinds of plants you should avoid planting with Dahlias. Although a lot of people consider growing Dahlias to be fairly easy, but these plants are rather sensitive.
To ensure optimal growth and health of your dahlias, it is best to avoid planting vegetables such as cauliflower, broccoli, and cabbage in close proximity. These plants are not ideal companion plants for dahlias due to the potential for shared pests and diseases. Additionally, they may compete for nutrients in the soil, which can negatively impact the growth and development of both the dahlias and the vegetables.
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If you grow Dahlias with overly aggressive or even harmful plants then the growth of the Dahlias will be stunted. In the worst-case scenario, some of these bad companion plants can kill off the Dahlia tubers by simply absorbing all the nutrients in the surrounding soil. While others can choke the life out of the Dahlia stems, in either case, it will not end well for the Dahlias. It is extremely important to choose wisely what you plant next to your Dahlias, especially in smaller gardens.
While Dahlias tend to grow relatively easily under ideal circumstances, but they tend to suffer if there is too much competition around them. I won’t go into specific plants to avoid, or else you would be reading for a year, but you will get a general idea. If you want to know what are the best mulches for Dahlias then check out my recent article Best Mulch For Dahlias ( Top 9 Mulches ).
What Not To Plant With Dahlias
When deciding what to plant alongside dahlias, it’s important to consider their growth habits, nutrient requirements, and potential competition for resources. Generally, it is advisable to avoid planting aggressive or fast-spreading plants that could overshadow or crowd the dahlias. Additionally, plants with similar water and light requirements are typically the best companions for dahlias.
Some plants to avoid planting with dahlias include tall or dense-growing plants that may shade or compete for nutrients, such as large shrubs or trees. It’s also wise to avoid planting vegetables or herbs with extensive root systems that may interfere with the dahlia’s roots. Furthermore, plants that attract pests or diseases that can affect dahlias, such as aphids or powdery mildew, should be avoided as well.
Vines
Vines or climbing plants do look good on a fence or if they are growing up a wall. There are some excellent vines like the Clematis which do contrast well with Dahlia flowers, however, you have to be really careful how close you plant them together. Vines tend to grow relatively fast, and if you allow them to grow up the stem of the Dahlias, they might even look good for a while, but sooner or later they will damage the Dahlia.
Vines that tend to use suckers to grasp onto things are extremely harmful to Dahlias, especially if the vines tend to be mature ones. Most Dahlias will not be able to support the weight of a vine, so make sure to plant them a couple of feet apart and trim the vine if it is trying to climb up the Dahlia. Climbing roses should also be avoided at all costs, especially if they have thorns as they can damage the stem and the leaves of the Dahlias. If you want to know the pros and cons of mulching Dahlias then check out my recent article Mulching Dahlias ( Top 7 Pros & Cons ).
Shallow Rooted Plants
Dahlias have thin and fragile roots, especially if the clump of tubers is relatively small. Dahlias are planted close to the surface, which means that their roots will also be relatively shallow. As Dahlias do not handle well competition, you should avoid planting plants that also have shallow roots right next to the Dahlias. Mature plants that have shallow roots will easily suck the soil dry around them, and the Dahlias will struggle as they can not penetrate the soil deep enough due to their weak roots.
On the other hand, you can plant plants with deep roots right next to the Dahlias, as they will absorb nutrients and water from deeper in the soil, which allows the Dahlia tubers to live off the topsoil. If you are growing your Dahlias in clay soil then check out my recent article Growing Dahlias In Clay Soil ( In 7 Easy Steps ).
Vegetables
It is becoming more and more popular to plant flowers in vegetable gardens, not only do they look good but they also help with pollination. However, Dahlias should not be planted with vegetables, as most vegetables tend to be rather hungry when it comes to water and nutrients. If you plant your Dahlias right next to some vegetables then one of them will become stunted, and usually, the Dahlias are more likely to suffer.
Vegetables tend to attract a lot of pests, from slugs, snails, aphids, and so on, these pests will not shy away from eating the Dahlias, so try to avoid planting vegetables too close to your Dahlias.
Plants That Grow Larger Than The Dahlias
Large Dahlia tubers will grow larger plants, than the ones that have smaller tubers. This means that even if the Dahlias should in theory grow to around 6 feet, most of them will stay at around 1-3 feet for the first couple of years. Established plants that will grow larger than the Dahlias should be avoided, as they will be competing for sunlight, water, and nutrients at the same time. If you already have a relatively large plant growing next to your Dahlias then simply replant the Dahlias.
Thick Ground Cover Plants
Ground cover plants do look amazing in a garden, and even around the Dahlias. The main problem with thick ground cover plants is that they tend to retain a lot of water. In some parts of the country, this could be a major benefit but in other parts of the country, this could lead to the Dahlia tubers rotting. The main killer of Dahlias tends to be root or tuber rot, and this tends to happen if there is excess water or moisture around the roots.
Grasse
Grasses tend to be somewhat problematic when it comes to growing Dahlias, especially if the grass is short and tends to spread way too fast. Grasses have shallow roots, which means that they will compete for nutrients with the Dahlias. In addition to this, certain grasses will make a thick layer of roots just below the soil, which can easily choke out the smaller Dahlia tubers. If you want to plant your Dahlias in the middle of your lawn, then make sure to clear the area around the Dahlia tubers and simply use some kind of mulch to stop the spread of the grass.
Do Not Allow Weeds To Grow Next To Your Dahlias
Although this is a no-brainer, but getting rid of weeds can be a chore, especially if you have a larger garden. Weeds tend to grow a lot faster than Dahlias do, and if you allow them to grow next to the Dahlias then they will outcompete the Dahlias in terms of nutrients, water, and even sunlight. At this point, the Dahlias will become stressed, stressed plants attract slugs, and they do love eating the Dahlias.
Key Takeaways
- You should avoid planting Dahlias with vines, as these tend to grow relatively fast, and if given the opportunity they will climb up the Dahlias, which usually damages their stems. Plants that have shallow roots will compete with the Dahlias if they are too close together, in the worst-case scenario the Dahlia tubers can simply dry out in the ground. Grasses should also be avoided, especially if they spread relatively fast, they will outcompete the Dahlias for water and nutrients.
- Planting Dahlias into the grass is not a good idea as their roots will choke the Dahlia tubers.
- Make sure that any nearby plant doesn’t come into direct contact with the Dahlias, as the friction will damage the Dahlia stems.
