Caring For Your Mother Plants

By Harley Smith
Published: December 1, 2016 | Last updated: April 10, 2017 01:42:54
Key Takeaways

The nutritional requirements of mother plants—stock plants raised to provide cuttings for starting new plants—are significantly different from plants raised for optimal yields. The key is ensuring the plants have enough stored energy to make healthy, hardy cuttings. Harley Smith has the details.

Source: Kuzsm/

Mother plants are stock plants specifically raised to provide cuttings for starting new plants. The cuttings, also known as clones, are genetically identical to the mother plant, and if grown in a controlled environment, will develop into daughter plants with the same superior characteristics as the mother plant.


Since cuttings take time to develop roots, the clones must rely on stored water and carbohydrates in the stems and leaves to provide the energy necessary to develop vigorous new roots. Therefore, the nutritional status of the mother plant is critical to the rooting and recovery time of the tender clones.

Nutritional requirements of mother plants

The nutritional requirements of mother plants are significantly different from plants raised for optimal yields. Mother plants require balanced nutrition specifically formulated to slow down excessive vegetative growth and increase the carbon-to-nitrogen ratio stored in the shoots. If a mother plant is fertilized with too much nitrogen, it will grow quickly, but it will produce soft tissues with poor carbohydrate reserves.


About 25 to 30% of a plant’s energy is used to change nitrates into an organic form of nitrogen used for vegetative growth. An overabundance of nitrates will deplete the sugars in the shoots and leaves, reducing the amount of fuel available to stimulate new root growth. Therefore, a good mother plant fertilizer should provide just enough nitrogen to support a healthy root-to-shoot ratio, but not so much nitrogen that the plant has to burn up most of its stored sugars just to assimilate the nitrates.

A good mother plant fertilizer must also be formulated to strengthen the plant’s cell walls and improve its water-holding capacity and stress tolerance. Excess nitrogen fertilization, as found in many standard grow formulas, produces large plant cells with thin cell walls. Cuttings taken from the new growth of overly vegetative plants tend to be weaker and more susceptible to wilting and fungal infection.

Try using half-strength nutrient formulas whenever possible, preferably with about a 1:1 potassium-to-nitrogen ratio. Excessive potassium tends to translocate the nitrates to the shoots, which can make the nitrate imbalance worse, so try to keep nitrate fertilization just inside the adequate range.


When in doubt, it’s better to err on the side of caution. If the mother plant starts to show signs of a nitrogen deficiency, it’s easy to spoon feed the plant with a little nitrogen supplement. The plant will start to respond in just two or three hours. But overdoing it with nitrate-nitrogen weakens the whole plant and could take weeks to correct.

The ideal mother plant fertilizer should also be formulated to stimulate the uptake of calcium. Calcium is taken up through the roots and transported to the new growth, where it forms calcium pectate glue that bonds the cell walls together. A calcium-rich mother plant will produce thicker stems, stronger cell walls and a healthier vascular system. The stronger the vascular system, the more efficiently a mother plant can take up water and nutrients, allowing more sugars and nutrients to be stored for future use.


The use of amino acid supplements in a mother plant nutrient formula can dramatically improve the mother plant’s uptake of calcium. In conventional hydroponics, calcium ions are dissolved in the nutrient formula and are taken up into the roots through simple osmosis, one ion at a time. But if a blend of specific amino acids are added to the nutrient solution, calcium ion channels in the roots are opened, allowing calcium to be taken up thousands of times faster than simple osmosis.

The calcium is then used to build strong, new cell walls and improve the plant’s natural resistance to environmental stress and disease. Higher levels of calcium also tend to restrict the transport of excess nitrates to the shoots, producing plant cells with smaller, but thicker cell walls, ideal for vigorous clones.

Other biostimulants such as humic acid and kelp extracts are good additives for mother plants. By combining humic acid and seaweed extracts in a 5:2 ratio, mother plants can produce up to 50% more of a powerful anti-oxidant called superoxide dismutase (SOD). Elevated levels of SOD protect the cell walls, the chloroplast membranes and the mitochondrial membranes during times of heat and drought stress.

Since cuttings taken from mother plants are under extreme stress, the heightened levels of plant protection agents accumulated in the tissues will help ensure the survival of the clones until they can develop their own root structure. The extra antioxidants will also help the mother plant recover faster.

Seaweed extracts can also be used as a foliar spray for mother plants. Seaweed extracts are rich in cytokinins, the growth hormones that stimulate cell division. Research shows when cytokinins are applied to shoots as a foliar spray, nutrients are attracted towards the growth hormones and are drawn into the leaf tissues. Cytokinins also help keep the plant tissues in a juvenile state.

For example, if you add a drop of water containing cytokinins to a leaf, then cut the leaf off and lay it on a table, the whole leaf will turn brown except for an island of green where the cytokinins accumulated. Mother plants treated with seaweed extracts will accumulate nutrients and stay green longer, and cuttings taken from the new growth will root much more quickly.

Seaweed foliar sprays for mother plants work even better when combined with fulvic acids. Fulvic acids are small organic molecules that chelate iron and other trace elements and help transport them into the plant.

The fulvic acid molecules surround the metal ions like a claw, transport them across cell membranes and release them inside the cell where they are needed the most. Once inside the cells, the trace elements activate enzymes that can do thousands of chemical reactions per second.

The combination of seaweed extract with fulvic acid is a powerful one for mother plants. The hormones in seaweed extracts stimulate the development of more lateral branches with tighter internodal lengths and the trace elements in the fulvic acid amplify the effects of the seaweed and activate essential growth hormones.

If you can grow bushier mother plants with tighter nodes, it will produce many prime candidates for cuttings. Misting your mother plant with a seaweed/fulvic acid combo a couple of weeks before cuttings are to be taken will ensure you have many viable cutting candidates to choose from. For best results, also add a wetting agent such as yucca to the mix.

Wetting agents allow the solution to spread out in a thin film on the leaf surfaces, providing better coverage and more effective absorption by the plant. Foliar sprays, when used in conjunction with a well-formulated mother plant fertilizer, can be thought of as stage zero of plant propagation from cuttings.

If you want faster rooting and healthier, more vigorous clones, pay close attention to the nutritional needs of your mother plants. Stored energy is the key. Once the cutting is removed from the mother, it will have to rely on the stored water, minerals and carbohydrates contained in the excised plant tissue.

So treat your mother well with balanced nutrition and high-quality supplements. Healthy moms, healthy clones!


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Written by Harley Smith

Profile Picture of Harley Smith
Harley Smith is the director of research for NPK Industries. A veteran in the hydroponics industry, Harley has more than 18 years of consulting and educating experience. He is regarded as an expert on plant nutrition and organic bio-stimulants, performing research and new product development in the US and Europe.

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