Plants will grow and grow as long as nature provides for their needs! However, will their roots stop growing after flowering?
Plant roots still grow during flowering but may be inhibited if there are not enough materials such as sugar, nutrients, and more produced by the leaves. Stunted root growth may be due to 1) root-bound, 2) compact soil, and 3) internal and external factors.
Roots will still do their job to provide the essential materials for every part of the plant – flowers, stems, and leaves. Root growth and flowering are equally important processes that ensure the survival of the plant and the species, respectively.
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Plant roots still grow during flowering provided that it has enough space and nutrients to sustain its growth. However, root growth will be affected by the distribution of auxins (growth hormones) which may be directed to promote flower development.
Plant roots will adapt to the biological, chemical, or physical properties of growing in a medium (soil or water). Being the organ of the plant responsible for nutrient and water uptake, it will continue to grow to reach more nutrients deeper in the soil. This is needed to sustain the plant’s other biological processes such as cellular respiration, photosynthesis, and reproduction.
Reproduction in plants can occur through flowering. Flowers serve as the reproductive organs of plants that produce seeds.
Given that flowering is important for the perpetuation of the plant’s species, it may cause the plant to divert all auxins and resources to produce flowers.
The idea of root growth affected by flowering comes from 1) anecdotal evidence and 2) scientific studies.
Anecdotal evidence and testimony by different gardeners and growers give varying answers. Similarly, scientific studies have no solid conclusion on the relationship between flowering and root growth due to how the interaction differs between plant species and conditions.
Nevertheless, I am here to help as much as I can!
Some gardeners have theorized that annual plants prioritize resources into speeding up the growth rate of flowers to expedite reproduction. Since annual plants die every season, prioritizing reproductive organs does make sense as it ensures the survival of the species at the expense of roots.
Though a reasonable theory, there is no solid consensus on whether this is true or not. In discussions on boards, forums, and other sources, gardeners and growers give differing responses.
Some gardeners argue that root growth is stunted when the plant is flowering. Others state that the roots still grow or that they grow even faster while flowering.
To summarize, there is no clear answer. We do have to take into consideration the varying conditions, plant species, and cultivars that form the bulk of the anecdotes between gardeners.
Scientific studies give varying conclusions on the relation between root growth and flowering. It is known that different plant parts compete for the materials (such as sugars, auxins, vitamins, and nitrogenous substances) produced by the leaves. However, the prioritization and allocation of these materials differ between species, varieties, and cultivars.
In one study, it was concluded that root-formation and flowering were antagonistic systems for the plant under study. However, flower initiation inhibited root growth. The distribution of auxin, the hormone group that regulates growth, is allocated to flowering rather than root growth.
Another study from the Oregon Ornamental and Nursery Digest used Rhododendron as a basis. They concluded that the influence of flowers may have an inhibiting effect on root growth or none at all, depending on the plant.
The amount and type of materials produced by the leaves can determine how much roots and flowers compete for growth. Some plant species are more efficient and allow roots and flower development at the same time.
All in all, it is safe to conclude that root growth in relation to flowering is highly dependent on several interplaying factors. The anecdotal evidence lines up with the scientific studies whereby the varying species and conditions dictate root growth.
The roots of plants may have an effect on the flowering of plants. It has been observed that plant species with deeper roots flower later relative to other plant species.
This relation between root depth and flowering was observed by a group of researchers assembling possibly the first functional trait database for a North African steppe which covered 104 species. They explain that this may be a case of temporal niche partitioning.
Temporal niche partitioning (also known as conditional differentiation) is a phenomenon where organisms like plants change their patterns and abilities in response to external conditions to increase their chances of survival.
Example: Plants with deep roots have better access to water in the soil which will allow them to survive longer and flower later when there is less competition for pollinators
Temporal niche partitioning allows co-existence between competing species. Think of it as two drivers in an intersection without any stoplights. The driver that gives way allows the other driver to move forward, preventing traffic accidents.
Apart from species being a consideration, there are plenty of other reasons why root growth is inhibited. These include 1) root-bound, 2) compact soil, and 3) internal and external factors.
Root-bound (also known as pot-bound) is a condition wherein roots become a tangled and dense ball, limiting the space for root growth and development. This also limits the amount of nutrients and water that plants can access.
Compact soil prevents root growth. Plants produce a chemical signal “ethylene” which prevents roots from growing in the presence of hard and compact soil.
An international Research Team from the University of Nottingham and Shanghai Jiao Tong University have recently discovered the mechanics by which plants stop root growth. The plant signal “ethylene” causes the plant roots to stop growing in hard and compact soil. By disabling this signal, roots will still grow even in the presence of compact soil.
Internal and external factors contribute to root growth. This means that root growth, and plant growth is dictated by the internal processes of the plant in relation to its external growing conditions.
Internal factors include plant genetics, hormones, photosynthesis, and cellular respiration, among others. External factors include environmental conditions such as soil quality, water access, light intensity, temperature, humidity, other organisms, pests, and diseases, among others.
Affecting these factors to be optimal for plant growth and development will greatly influence the growth rate of the roots. Optimizing these factors can be done by providing the best growing conditions recommended to a certain species of plant.
Example: Succulents do best in dry environments with minimal water, nutrients, and sunlight. Tropical plants however need more humid environments with an adequate amount of water, nutrients, and sunlight.
- Roots still grow during flowering but may be inhibited or hindered if there is not enough materials produced by the leaves. This is dependent on the plant species and its growing conditions.
- Roots may have an effect on flowering. It was observed that plants with deeper roots flower later which is indicative of temporal niche partitioning (conditional differentiation).
- Root growth may be inhibited or stunted by other causes namely: 1) root bound, 2) compact soil, and 3) internal and external factors. Creating the optimal growing conditions ensures the best root growth.
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- “Chapter 13 – Effect of Internal and External Factors on Root Growth and Development” by Lynch et al in Marschner’s Mineral Nutrition of Higher Plants (Third Edition) 2012, Pages 331-346
- “Deep roots delay flowering and relax the impact of floral traits and associated pollinators in steppe plants” by Berrached et al in PLoS One. 2017; 12(3)
- “Effect of Flower Buds on Rooting Response – Tested” by D.G. Adams & A.N. Roberts in Oregon Ornamental and Nursery Digest 9(3): 1,2,56
- “Flowering plant life cycles” by n/a Science Learning Hub
- “Plant Growth” by n/a in Lumen
- “Rates of Root and Organism Growth, Soil Conditions, and Temporal and Spatial Development of the Rhizosphere” by Watt et al in Annals of Botany, 2006 May; 97(5): 839–855.
- “Research reveals how crop roots penetrate hard soils” by n/a in UK Research and Innovation
- “Root Growth” by n/a in CK-12
- “Scientists discover cause that prevents roots from growing in hard soils” by n/a in Open Access Government
- “Temporal niche partitioning as a novel mechanism promoting co-existence of sympatric predators in marine systems” by Lear et al in Proceedings of the Royal Society 288(1954)
- “The effect of flowering on adventitious root-formation” by Hassan Hosney Ahmed Selim in Agricultural University of Wageningen