Turn Your Weak Roots into Strong Survivors

By Nicci Mills
Published: December 1, 2016 | Last updated: May 4, 2021 06:24:22
Key Takeaways

Taking an out-of-sight, out-of-mind approach to your plants’ roots will only result in weak, rotting roots and unhealthy plants. To build strong roots, create a plan for the environment beneath the soil. Nicola Mills tells us how.

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Plants sometimes need an extra boost to strengthen or establish their root systems. Whether starting from seed or supporting a growing plant, you need that foundation to provide structure and pull in water and nutrients. Most plants are also unlikely to grow above their base or crown roots without a deeper, stronger system below. When that structure is severed by transplanting or unearthing, plants quickly weaken and become susceptible to diseases like root rot.


Although applying the right balance of fertilizer and water can help with recovery from such a shock, the wrong amount can easily cause fatal problems. However, when disaster strikes, applying root stimulators and other enhancements can help rejuvenate your soil and the plants that rely on it. Fundamentally, the best approach to developing more robust roots is creating a clear plan for soil and plant care that is grounded in cultivating a healthy below-ground environment.

Building Better Soil

The first step in that plan should be choosing the right fertilizer or soil enhancer, and this starts with a soil test to accurately measure nutrient levels. Determining your indoor garden’s unique needs is important because greenhouse-grown plants have only known the intensive care of their artificial conditions.


As a result, they cannot handle actual soil and have a harder time adapting to different environments, whether that be in one’s backyard or indoors. However, appropriate plant care can help by mimicking the native climate for your plants in terms of water, light, humidity and temperature.

After assessing your soil needs, you can then turn to the plants themselves. In particular, over time, they will deplete the nutrients originally provided by their soil, even as regular watering leeches those resources from the soil. Yet, unlike the great outdoors, indoor soil can only be replenished with additives and fertilizers.

Traditional fertilizers, though, have multiple disadvantages, from their odorous smell to basic costs, seasonal effectiveness, and storage and use requirements. Soil enhancers and stimulants, on the other hand, provide easy-to-use alternatives that can save time and money by helping build soil and root structure in kind.


Both synthetic and natural options within these categories should be applied according to their instructions to avoid damage, although natural products are less likely to harm plant life. In general, fertilizers and stimulants should be applied fairly regularly—around once a month or more often during the hard work of flowering or fruiting and the fast growth of spring. Be sure to monitor and analyze changing conditions to help adapt to your plants’ needs, with weak growth and yellow-green color specifically signaling poor nourishment.

"When it comes to root growth, you should aim for stimulating potassium and phosphorus rather than nitrogen."

Rejuvenate Roots with Phosphorus & Potassium

Plants rely on many naturally occurring micronutrients. However, nitrogen, potassium and phosphorus are vital to overall plant growth, especially photosynthesis, cell division, and fruit, flower and seed development. Accordingly, fertilizers are rated by an N-P-K ratio for the contained percentage of each. As these nutrients are used up over time, they will need to be replenished, and fertilizers provide a means to prevent deficiencies by doing just that.


When it comes to root growth, you should aim for stimulating potassium and phosphorus rather than nitrogen, which promotes growth while weakening the roots, flowers, and fruits that the previous encourage. Phosphorus, in particular, not only helps root systems grow, it also balances high nitrogen levels resulting from drought and compacted soil. Potassium, on the other hand, encourages dense and strong root growth.

Both are especially well-suited for organic gardening and for younger plants, as these additives can easily be naturally sourced and are not harsh on plant life. At the same time, fertilizers also carry other nutrients, including silicon, which improves pest, disease, drought, heavy metal and salt resistance.

The main natural sources for these soil enhancements are phosphorous-laden livestock manure, high-potassium granite meal and wood ash, and low-nitrogen rock phosphate and bone meal. For both phosphorus and potassium, you can get the same levels of nutrients from synthetic fertilizers, which are easy-to-use and ideal for plants already suffering from deficiencies. In either case, the best time to apply these nutrients is before planting, by working fertilizer several inches into the soil around existing roots.

Stimulate with Root Boosters

Root boosters, meanwhile, combine various vitamins, hormones, and other elements that support root growth in order to improve the uptake of nutrients through existing roots. While these products often tout the benefits of vitamin B1 or thiamine, any positive results are undoubtedly caused by additives, including humic acids, kelp and rhizobacteria like mycorrhizae.

Rhizotonics actually contain myriad root-stimulating hormones, along with bacteria that stabilize and digest nitrogen and minerals in the soil. Within B1 boosters, it is the root stimulators like auxins that stimulate roots, such that water and a small amount of fertilizer would better boost growth than thiamine alone.

Auxins are naturally occurring plant hormones that often come as part of B1 boosters but that actively create strong, deep root systems. Some examples include indolebutyric acid, naphthylacetic acid, and indoleacetic acid, the latter of which specifically helps plants focus on cell growth.

Auxins stunt crown and other growth in order to establish lateral roots, so they can be especially helpful in nurturing transplants and growing plants from cuttings. However, they should not be applied to seedlings, as doing so will stunt plant and primary root growth. In bringing together auxins and other elements, though, root boosters can improve nutrient up-take by transplanted or otherwise severed root systems and so help as much as initial root growth.

Nurture Roots with Mycorrhizae

Another common ingredient in root boosters is mycorrhizae, which is a group of root-colonizing fungi found all over the world except Antarctica. These fungal growths share a mutually beneficial, symbiotic relationship with most of the world’s land plants. Mycorrhizae specifically aids in the uptake of minor nutrients and can be traced back to the earliest fossil records as filaments that penetrate and become extensions of root systems.

In so doing, they help absorb water and nutrients, deter bacteria and other fungi, and build stronger underground structures. Plants are so dependent upon mycorrhizal fungi that many woody plants like oak trees would actually die without them entangled in their roots.

"Because plants get their nutrients from their root systems, ensuring root health is the most important part of any form of gardening."

Mycorrhizae boosters are generally included with growing media or as water-soluble mixes to help mimic the symbiotic relationship found in pristine soils. Such treatments are especially well-suited to building root systems in hydroponic gardens and rebuilding bacteria populations within urban soils because they support adaptation.

Furthermore, this natural soil enhancement is a great solution for improving nutrition, drought tolerance, and overall survival of plants in organic gardens. More generally, mycorrhizae boosters can be a strong foundation for starting and maintaining indoor plants and gardens.

Because plants get their nutrients from their root systems, ensuring root health is the most important part of any form of gardening. For indoor gardens, in particular, mimicking natural conditions can help strengthen seedlings, transplants, and established plants alike. However, using soil enhancements to promote root growth is not a one-size-fits-all approach. Instead, you should focus on adapting to your plant and soil’s unique needs in order to take care of them when they need it.

Proper care and watering remain the best ways to maintain plant health, so use the above information to help balance soil enhancements and to cultivate strong roots and healthy plants.


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Written by Nicci Mills

Profile Picture of Nicci Mills
Nicci Mills is a self-taught horticulturalist with a keen interest in alternative growing systems. She writes for a number of online publications.

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