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Can You Grow Onions Upside Down – What’s The Best Way?

Many people face the issue of small spaces and big garden dreams. Utilizing your space to its fullest may mean using the aerial space above your soil. Many plants and herbs can grow effectively upside-down, but can you grow onions upside down?

Growing onions upside-down like one might with tomato plants, unfortunately, does not work well for onions or other bulbs like garlic. On the other hand, if one accidentally plants a bulb root side up, there’s no need to be concerned here; the bulb knows how to sort itself out, so your harvest is not affected.

Read on to learn more about upside-down gardening and why it’s not best suited to onions. 

Why Can’t Onions Grow Upside Down? 

Onions are not the best candidate to grow in an inverted set-up and are best left to sit in the soil for several reasons.

Bulbs and rhizomes depend on gravity to determine which way is up or down. This is why if you accidentally plant one of these upside-down, they will eventually right themselves and find out which way to grow roots and which way to grow shoots. This can be an issue when planted in an upside-down garden; your plant may naturally want to put the roots growing downwards instead of up into the container. 

Onions also have shallow root systems, so a deep container would be wasteful for a plant with little depth requirements. Additionally, each bulb will give way to a single onion, which may not be an effective use of the three-dimensional space inverted gardening gives. 

Another issue with attempting to grow onions this way is that onions need to emerge above the soil line as they mature, and this is a good sign your onions are growing well. They cannot mature properly if the entirety of the bulb is out of, or stuck inside, the soil. 

Watering concerns with upside-down gardening can also be detrimental to your onion yield. The bag or container used to grow plants upside down has a greenhouse-like effect because it keeps the soil warm, though, in the summer heat, this can have its drawbacks requiring more frequent watering. This can lead to overwatering, giving way to rot and attracting pests and other diseases. 

If ground space is an issue, consider prioritizing what to plant this year and what crops in your plan might be better suited for the upside-down space. 

Benefits and Drawbacks of Upside Down Gardening

Some small-space (or space-conscious) gardeners love the practice of upside-down gardening, while others think of it as an over-hyped trend. Here are some benefits and drawbacks of the upside-down gardening method:

Benefits: 

  • Space-saving method of growing plants: using space that isn’t ground-space can be a saving grace for those who wish to garden but cannot due to limited outdoor square footage. 
  • Pests and diseases do not seem to affect inverted plants as much as plants in the ground: Many issues of diseases in the garden originate from soil-borne pathogens splashing up onto the leaves and fruit when watering. This method has minimal to no contact with the soil and foliage, thus reducing the risk of spreading diseases to the fruit. 
  • Ease of water and nutrient delivery to the foliage and fruit of the plant. The container gets watered at the top, and gravity gives your plant’s fruit and foliage quicker delivery of vital water and nutrients. 

Drawbacks

  • Limited options for suitable plants: As mentioned earlier, bulbs or rhizomes are not well suited to this type of planting, nor are other shallow-root crops. 
  • Potential weight issues to consider: Heavy plants such as large tomatoes can cause weight stress on your container and its mount. This can lead to a collapse which may ruin the yield or severely stress your plant. 
  • Plant stress from chemical signals fighting gravity: Plants naturally grow up towards the light, so when they’re suspended upside down, these instincts still kick in. Plants grown upside down can curve and form a “U” shape, weakening their stems and making them more prone to breakage. 
  • Higher potential for wind or weather damage: Weakened stems results in a decreased ability to withstand heavy winds or rains. Stems can break, fruits can fall, and a whole season’s worth of growth can be damaged from one unexpected storm. 

It is the gardener’s preference when deciding how they want to set up their garden, whether with plants traditionally going in the ground, hanging upside down, or both. Knowing the pros and cons of any method is crucial to staying informed and making the right decisions regarding the individual needs of your crops. 

What Plants are Suited to Upside Down Gardening? 

Some plants can be well-suited to growing upside down. Plants with deeper root systems, lightweight fruit or flowers, and average to above average water requirements may thrive under these conditions. 

Smaller varieties of tomatoes, like cherry tomatoes, can perform well when grown upside down. Hot peppers are also smart since they are lightweight and can withstand the heat generated through the greenhouse-like effect of the container being warmed by the sun. Herbs such as basil, parsley, and cilantro are appropriate for this type of gardening. 

Fruits like strawberries, blueberries, and grapes may also be contenders, though the weight of the grapes should be considered ahead of time to ensure enough support while they grow. 

Fruiting plants are not the only things that can get upside-down treatment. Flowers or other ornamental plants with a vining growth habit are excellent for this growth. They can follow their natural growth habit without taking up space in the ground. Ivys, pothos, petunias, and bougainvillea are beautiful additions to the garden and may be more attainable for those battling with compact spaces when planted less conventionally. 

Final Thoughts

Though upside down gardening has its positives and drawbacks, it’s important to select the right plants to grow upside-down if that is the desired method of planting. 

Onions, garlic, and shallow-rooted crops do not do well under the conditions of upside-down planting and are best going directly into the ground for optimal development and yield.