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Harley Smith

Seaweed Extracts for Bushier Plants!

Indoor gardeners often have low ceilings with space limitations. If the plants grow too close to the lights, excessive heat can cause the plant to go into “photorespiration”, a state in which the plant uses light energy to burn carbohydrates instead of producing them. Symptoms show up as heat stress. The new growth stops developing, leaves turn pale and eventually become brown and crispy. So here are some helpful hints to keep plants short and stocky:


Choose the right genetics. If you have low ceilings, select varieties of plants that better fit your space. For example, choose “determinate” varieties of tomatoes instead of “indeterminate” varieties. Indeterminate tomatoes are vine crops that could reach lengths of 35 feet or more, making them difficult to train indoors. Determinate varieties are usually labeled as “bush” varieties or “patio” varieties. They stop growing after reaching a certain height. Also, try not to mix tall plants with short plants in the same garden. The short plants will be too far away from the lights to do their best.


Use full-spectrum lights. Plants need both the blue and red ends of the spectrum for photosynthesis, but the blue end of the spectrum is most important for keeping plants short and stocky. For example, standard warehouse HPS lamps are rich in the yellow and red end of the spectrum, but they have almost no blue. So the plants will stretch, looking for the sky! But if the plants receive enough 460 nm wavelengths (sky blue), they will stop stretching. The plants will be shorter and stockier with thicker stems and dark green foliage. The blue wavelengths also stimulate the leaf stomata to open, taking in more carbon dioxide for photosynthesis. Try to keep your enhanced-spectrum lights as close to the growing tips as possible, but far enough away to prevent burning them! Using light movers and air-cooled reflectors are also helpful.


Prune and train your plants. If you trim the growing tip of the plant, the natural plant growth hormones in the plant will be redistributed, stimulating more lateral branch development. For example, if you cut the growing tip of a basil plant, two branches will take its place. Trim the tips from those two branches, and four will take their place. The more you cut, the more it grows! Just make sure you trim back to just above the next node. A node is the junction between the stem and a leaf. The new buds develop from the nook just above the node. Proper pruning and training can maximize yield in limited space.


Spray with seaweed extracts. Seaweed extracts have natural plant growth hormones called “cytokinins”. Cytokinins break the apical dominance of the growing tip, and stimulate lateral bud development, producing bushier plants. Natural seaweed extracts can also have a downstream effect on flavor, color and aroma, since cytokinins literally pull nutrients into the developing branches. Just make sure that you use a raw, unadulterated kelp product. Some premixed seaweed products also include synthetic plant growth regulators (PGR’s). Many PGR’s, such as paclobutrazol, inhibit the plant’s natural hormonal balance and are often listed as known or suspected carcinogens! Natural seaweed products, on the other hand, often have positive, health-enhancing side effects! Just make sure to follow recommended dosages, and don’t spray more than once a week. Moderation is the key.


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