An approach to companion planting for asparagus that aims to separate fact from fiction and blend traditional wisdom, common sense, and current known science. A lot of information on companion planting online and in gardening books is confusing, wrong, and based on folklore, myth, and rumor. But companion planting is a real, if misunderstood, thing that can make your garden healthier and more productive.
Companion Plants For Asparagus
I strongly believe that the best companion plants to interplant with your asparagus are strawberries, another perennial, and bush beans, a very productive and low-maintenance food crop.
Another option would be to use cover crops that are not edible if your goal is not to maximize food production.
But what is the point?
Companion planting can also be called intercropping, interplanting, and polyculture. If you're familiar with permaculture, you're likely already on board. The practice offers numerous benefits to your vegetable garden, including:
- Improved soil structure and quality.
- Maximized usage of available garden space.
- Management of weeds.
- Less disease.
- Biological control of pests and unwanted insects.
- Improved pollination.
- Increased biodiversity.
Here are the best companion plants for asparagus, followed by the worst ones. These recommendations are based on the most reliable sources available.
Edamame is just an immature soybean. They have several benefits beyond being an edible food crop. Edamame are excellent nitrogen fixers, capable of fixing up to 130 lbs of nitrogen per acre. And soybeans start fixing nitrogen when they are just a few weeks old. Edamame is typically planted in early spring, and the benefits of the nitrogen-fixing won't be seen in the current yield of asparagus spears but in next year's crop. The edamame will help nourish the ferns after the spears have been harvested. It's crucial to choose soybean varieties intended to be harvested as edamame since most soy isn't grown for this purpose. Edamame plants are larger than bush bean plants, growing up to two or three feet high, but don't require staking.
Although many legumes are excellent at nitrogen-fixing, most garden beans are not. This myth continues to be spread regardless. However, bush beans are still considered one of the best companion plants for asparagus because they are easy to grow, productive, and delicious. They produce abundant beans that keep coming as long as you keep harvesting. This makes green beans an excellent companion plant for almost every other plant. And even if green beans don't fix nitrogen in the soil, they don't deplete the soil of it either, and some studies show that they actually do share some nitrogen with nearby plants, making them an ideal companion plant to stick almost anywhere.
Strawberries are a delicious and valuable perennial, and they are one of the best companion plants for your asparagus — potentially the top choice. Asparagus and strawberries require similar growing conditions and have similar watering needs. The strawberry plants will help to shade out the soil and keep some weeds at bay. Add some organic mulch to your mixed asparagus-strawberry bed, and you have a low-maintenance and very productive food plot that will give back for years.
Cowpeas, or black-eyed peas, are a beneficial companion plant for asparagus. As legumes, they are an example of a bean that enriches the soil by fixing nitrogen. This natural fertilization promotes healthier asparagus growth without the need for chemical fertilizers. Cowpeas can be used as a cover crop or living mulch as well as a food crop.
Fava beans are one of the best proven nitrogen-fixing legumes — up to 250 lbs of nitrogen-fixing per acre. They have been used for this purpose in commercial agriculture for a long time, and you can absolutely do this yourself in your home vegetable garden and for your asparagus patch. And fava beans are edible, easy to grow, and delicious.
A perennial bed like asparagus is a perfect host for your kitchen herb garden from a purely practical standpoint.
Certain herbs like basil and parsley are also supposed to repel the asparagus beetle with their unique chemical compounds.
Tomatoes emit a compound called solanine that can repel the asparagus beetles and other pests while also repelling nematodes, which can harm asparagus roots.
Planting tomatoes as a companion plant to asparagus is an example where the — often very tall — tomato can rise above the large ferns of the asparagus after harvesting. It is best to plant the tomatoes in a row behind the asparagus patch and not to disturb the patch itself as tomatoes are often planted very deep and their roots can reach enormous depth.
That said, tomatoes are heavy feeders, and I would caution against planting them in poor soils. If you plan to add compost in the fall, or plant a cover crop, after all the harvesting, this might not be a problem.
I would avoid tomatoes as a companion to asparagus unless my patch was well established and I knew my soil was of very high quality.
Companion planting for asparagus and other vegetables can take the form of living mulches or cover crops. These plants might not feed you, but they will feed the soil after their death, protect it from erosion, keep weed pressures down, and might even be beneficial for insects and pollinators — consider native varieties to your region as those can be especially effective.
Some living mulches you might consider: crimson clover, medium red clover, white clover, subterranean clover, oats, buckwheat, and winter rye.
One study showed that winter rye planted after the harvesting season for asparagus was over, reduced weed growth significantly.
Make sure to check out my article on the best mulch for asparagus, which deals with the topic of organic materials like hay, straw, wood chips, etc., being used as protective mulches.
The benefits of mulch are numerous, and they certainly don't have to be a living cover crop.
I prefer to use companion planting to grow food crops and have not yet started exploring living mulches and cover crops beyond some experimentation with tillage radish.
The Worst Companion Plants For Asparagus
The worst companion plants for asparagus are any plant or vegetable that is a heavy feeder, any vegetable that will struggle to survive because the asparagus ferns are shading it out, any vegetable requiring immense amounts of watering and/or fertilization, or anything that will disturb the asparagus crowns and roots.
Root vegetables are probably one of the worst companion plans for asparagus for this reason. I would avoid them.
It is also important to take your own notes using something like a garden planner or similar and to make your own observations. Be your own scientist because although emerging studies are exciting, there is still so much unknown to us.
More Asparagus Companion Planting Considerations
Beyond deciding which companion plant for asparagus you prefer for your garden and circumstances, you need to consider the asparagus ferns when making your choice.
Asparagus is a perennial plant that can last for more than 15 years. In early spring, it produces tender and edible spears that vanish long before the rest of the garden starts producing food. Once the edible stalks are harvested, the plant will grow up to 3 feet tall and 4 feet wide, forming fern-like foliage that will last until the end of the growing season.
The ferns' purpose is to create the energy stored in the plant's underground portion to produce the following year’s asparagus crops. It is crucial to take care of the ferns after the harvest to ensure you will have good future harvests.
When choosing companion plants for asparagus, it is important to consider the size of the ferns — both vertically and horizontally. You don't want your selected plants to be in fruiting while overshadowed by the large ferns. To ensure that your companion plants thrive throughout the entire life cycle of the asparagus, it is important to choose plants that can handle the shade created by the ferns.
The goals of companion planting can be numerous; the first goal of the gardener is to simply avoid planting anything detrimental together.
The second goal is to maximize the space and best use our garden plots, raised beds, and containers.
Finally, companion planting can offer benefits like pest control, weed control, reduced disease pressure, attracting beneficial pollinators, not depleting the nutrients of the soil, water management, improved soil, maximizing harvest yields — and more.
Companion planting for asparagus will depend on your needs and your space, and you cannot go wrong with the choices discussed here.
- Crop Diversification for Asparagus in the Pannonian Pedoclimatic Region: Opportunities and Constraints. Link.
- Best Management Practices to Alleviate Deep-Seated Compaction in Asparagus (Asparagus officinalis) Interrows (UK). Link.
- Establishment of Asparagus with Living Mulch. Link.
- Google Book Preview: Plant Partners: Science-Based Companion Planting Strategies for the Vegetable Garden.
Make sure to check out my article on planting asparagus seeds — a comprehensive grow guide on the cheapest way to start a new bed, as well as my article on how to grow asparagus from crowns — the fastest and best way — but more expensive.
If you're still in the planning stages of your asparagus patch, how many asparagus plants per person will help you decide how much is needed to plant.