Whether you’re growing from seed, seedling, or clone, it’s important to have your hemp plants hardened off before being planted in the field. The hardening process can generate hardier transplants, which will reduce transplant shock and help your plants transition to outdoor living more quickly. So what exactly does it mean to be “hardened off?”

Hardened, Flourishing Hemp
Hardened, Flourishing Hemp

Hardening off is the process of taking a hemp clone or seedling and gradually acclimating it to harsher environmental conditions, such as a greater light intensity or increased wind. When clones or seedlings are propagated or germinated, respectively, we (growers) do everything in our power to ensure the clone or seedling will have the greatest chance of viability, and therefore we dial in the indoor environmental conditions to be as gentle and nurturing as possible. These environmental adjustments, such as increased humidity, increased heat, or light filtration are necessary for propagation and germination but lead to “babied” plants that are not optimized (yet) for outdoor cultivation.

To make matters even more severe, in lieu of the sun, some growers use grow lights or indoor lighting to propagate and/or germinate their hemp plants. This can lead to monumental shock if the plant is not properly acclimated gradually to outdoor conditions. Be careful if you or your grower is growing under lights and then transitions to an outdoor environment, especially in places like Colorado, where the sun is intensely magnified due to altitude.

Healthy Young Hemp Growing

Hardening is a fairly quick and easy process that can hugely benefit farmers. and plants themselves.

If your grower doesn’t harden the plants you purchase or if you wish to add some additional hardening steps before transplant, you can simply place your plant outdoors in a semi-shaded area and gradually begin to add in environmental conditions. If you have a greenhouse with roll-up sides or a makeshift shade structure, this is even better. 

Make sure as you are starting the hardening process that your plants will not be subject immediately to high winds because this could snap the delicate stems and kill your young plants. Begin with your plants shielded from direct, intense sunlight and gradually move them (or remove shade cloth) to a higher intensity light. Use an overhead watering method, such as hand watering with a garden hose, and start with a low pressure. In the beginning, your plants will bend and droop due to the weight of the water. As your plants increase stem strength, they will be able to better hold their own weight after watering. During the final days of hardening, increase the pressure of water for overhead watering so it mimics the intensity of a rain storm. The hardening process can last anywhere between 2-10 days depending on the grower and the stage of plant growth.

By growing and planting hardened plants, you can expect the following:

  • Hardier, more robust plants
  • Greater root development 
  • Increased stem strength
  • Less chance of sun burning plants
  • Reduced transplant shock 
  • Greater airflow and less disease pressure among plants
  • Better nutrient uptake

Thick, Rooted Hemp Starts

When the frenzy of planting season is upon us, remember to create a hardening plan. As you develop your farm plan and planting schedule, ask your grower (the company you’re purchasing hemp clones / seedlings from) if they do the hardening process for you, or if this is something you should budget time and space for.

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