Over the years I’ve learned a few things about Amaranthus. One of the most important things for growing it successfully is what to and what NOT to plant with it.
So to get your companion planting with Amaranthus right avoid the plants found here.
Understanding Amaranthus
Amaranthus is a powerhouse plant with attitude. I first fell in love with these it when my neighbor’s “Love-Lies-Bleeding” variety cascaded over her fence like crimson waterfalls. But as with so many pants they have specific needs and some serious plant prejudices.
Getting its companions right matters. A lot. And it doesn’t matter if you’re growing amaranthus for its vivid plumes, nutritious seeds or edible leaves. The same advice will apply.
Amaranthus plants are particularly sensitive to competition, especially during their critical growing stages. Their root systems search aggressively for nitrogen and other nutrients, which can leave neighboring plants starving. And their impressive height and breadth mean they cast substantial shadows, which can spell disaster for sun-loving companions.
Getting it wrong doesn’t just affect your other plants. It impacts the amaranthus itself. When forced to compete too hard they will produce fewer plumes and may develop weaker stems prone to flopping over during summer storms.
Plants to Avoid Planting with Amaranthus
1. Potatoes
Both crops are heavy feeders competing for the same nutrients, particularly nitrogen. What will happen if planted together? The potato yield will be pathetically small, and the amaranthus end up looking stressed and stunted.
The extensive root systems of both plants fight underground for resources and neither comes out winning. And potatoes prefer slightly more acidic soil than amaranthus, creating another point of contention.
2. Fennel
Fennel is notorious as a poor companion plant for many species, and amaranthus is no exception. It releases compounds into the soil that can stop the growth of nearby plants, including your prized amaranthus.
3. Corn
This might surprise you since both are tall growers but corn and amaranthus make terrible garden neighbors. Both are wind-pollinated plants with similar growing seasons and heavy nutrient requirements.
When planted together they compete intensely for nutrients, especially nitrogen. And their similar height means they’ll both be vying for the same airspace and can interfere with each other’s pollination. The result? Smaller corn ears and lackluster amaranthus plumes.
4. Most Brassicas (Cabbage, Broccoli, Cauliflower)
Brassica family members are notorious for their particular growing requirements, which in this case clash with amaranthus needs. The cabbage family plants are heavy feeders that deplete soil nitrogen rapidly, directly competing with your amaranthus.
5. Beans and Peas
This pairing might seem counterintuitive since legumes like beans and peas actually fix nitrogen in the soil. However, the problem lies in their growth habits and susceptibility to similar pests.
Amaranthus creates shade that legumes don’t appreciate. While climbing varieties of beans may try to use amaranthus as support, potentially damaging their relatively brittle stems. On top of that both plant types can attract aphids, meaning an infestation can quickly spread between them.
6. Dill
Like fennel, dill can inhibit the growth of nearby plants, including amaranthus. The aromatic compounds released by dill can interfere with seed germination and early growth of amaranthus.
Keep dill in a separate herb garden area where its allelopathic properties won’t harm your ornamental or vegetable plants.
7. Sunflowers
Both sunflowers and amaranthus are tall, dramatic plants that make bold statements in the garden. Unfortunately they also share an appetite for the same nutrients and moisture levels.
When planted too close together they will battle for supremacy with neither achieving its full potential. Their roots compete underground, while above ground, they may shade each other out depending on planting positions and sun angle.
8. Tomatoes
My tomatoes and amaranthus had a spectacular falling out when I tried partnering them. Both are warm season plants with significant nitrogen requirements during their growing season.
Tomatoes are also prone to various fungal diseases that can spread to amaranthus in humid conditions. The dense growth of amaranthus can also reduce air circulation around tomato plants, increasing disease risk. Keep these two garden favorites separated for best results.
9. Zucchini and Summer Squash
The sprawling growth habit of zucchini and other summer squashes makes them poor companions for amaranthus. They take up considerable ground space with their spreading vines and large leaves, potentially crowding out young amaranthus seedlings.
Both also require similar soil fertility levels, creating underground competition. I’ve noticed that when planted together either the amaranthus suffers or the squash yield decreases – sometimes both!
10. Mint
Never, ever plant mint near your amaranthus! Mint’s aggressive spreading habit means it will quickly invade the space needed by amaranthus roots. Its shallow but dense root system competes directly with amaranthus for water and nutrients in the top layers of soil.
11. Eggplant
Eggplants and amaranthus both prefer similar growing conditions, which unfortunately means they compete directly for resources. Both love heat and require consistent moisture and rich soil.
Their similar pest profiles also present problems – flea beetles that attack eggplants will happily move to amaranthus plants when given the opportunity.
12. Strawberries
The shallow roots of strawberries directly competes with amaranthus for nutrients in the top layer of soil. And the eventual height of amaranthus means it will shade strawberry plants, reducing their productivity.
13. Most Herbs with Strong Essential Oils
Rosemary, sage and thyme all contain strong essential oils that can inhibit the growth of nearby plants, particularly during seed germination and early growth stages of amaranthus.
They also prefer drier, less fertile soil than the rich, moist conditions amaranthus thrives in. When forced to grow together neither plant group performs at its best.
Good Companion Plants for Amaranthus
Amaranthus can work with some garden favorites though:
- Marigolds – these pest-repelling flowers help protect amaranthus from various insects
- Nasturtiums – attract beneficial insects while their low-growing habit doesn’t compete for light
- Sweet alyssum – creates beneficial ground cover that suppresses weeds without competing with amaranthus
- Onions and garlic – their different root depths mean they don’t compete directly with amaranthus
- Cosmos – these flowers attract pollinators and beneficial insects while not competing for the same soil resources
Tips for Successful Companion Planting
- Consider mature heights – plant shorter companions on the south side of amaranthus to ensure they still receive adequate sunlight
- Space appropriately – give amaranthus room to grow by spacing plants at least 18-24 inches apart
- Plan for succession – pair amaranthus with earlier or later maturing plants to minimize resource competition
- Enrich soil before planting – a well-fed garden has fewer resource conflicts
- Watch for signs of stress – yellowing leaves or stunted growth indicate competition problems that need addressing
Final Thoughts
Amaranthus is worth the extra planning effort. They bring unique color, texture and in many cases nutrition to your garden. Just remember that their imposing presence comes with specific companion planting requirements.
My garden journal is filled with failed experiments and successful discoveries about amaranthus partnerships. Through it all I’ve learned to respect its particular preferences rather than fighting against them. The reward? Towering, vibrant Amaranthus that become the centerpiece of my summer garden.
So before you plant your amaranthus this season remember this list of what not to plant alongside them. Your garden will thank you with healthier, more vibrant plants all around.