Alliums and Legumes: Why These Two Plant Families Don't Mix in Your Garden

Alliums and Legumes: Why These Two Plant Families Don't Mix in Your Garden

Are you a fan of legumes and alliums like onions and garlic?

Are you growing or thinking of growing these together in your gardening greenhouse?

Well, we've got some not-so-good news for you - these two plant families do not play well together. Let's dive into the reasons why.

First off, the unique flavor and aroma that you like so much in alliums, like garlic and onions, comes from sulfur compounds in the plants.

While these compounds may be great for us humans, they can actually harm other plants, especially legumes.

As alliums grow, they release sulfur into the soil, which can build up over time and create an acidic environment where legumes don't thrive in.

As you may already know, legumes, like beans and peas, are known for their ability to fix nitrogen in the soil, converting nitrogen from the air into a usable form for plants.

Unfortunately, alliums can hinder this process by producing substances that impede the growth of soil bacteria that are necessary for nitrogen fixation. So, growing them together in your vegetable and herb greenhouse will prevent this crucial benefit of companion planting.

But fear not, greenhouse growers! There are multiple ways to minimize the negative effects of planting alliums and legumes together.

The first option is to grow these greenhouse plants in separate areas of the garden, ensuring that they don't compete for resources or hinder each other’s growth.

Alternatively, you can stagger the planting times of the two families - for example, planting legumes in the summer and alliums in the fall or early spring. Planting them at separate times allows you to have enough produce from your greenhouse to last through the year.

Another effective technique is crop rotation, which involves planting different crops in the same area of the garden on a yearly basis. For alliums and legumes, this means planting legumes in one area for a year and then planting alliums in the same spot the following year.

This allows the soil to replenish its nutrients and prevent the spread of pests and diseases that can be carried by the soil.


In summary, while alliums and legumes may not be the best garden buddies, there are ways to make them work together.

By employing techniques like crop rotation and companion planting, you can continue to enjoy growing both families without sacrificing their growth and development.

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