5 Steps to Harden Off Seedlings

How to Acclimate Your Seedlings to Outdoor Conditions

5 Steps to Harden Off Seedlings

Starting seeds indoors is very rewarding, but it takes a tremendous amount of focus and effort to pull off. After you finish putting time, energy, and love into your indoor seedlings, you will want to make sure they continue to flourish outside. 

A key to ensuring their success includes “hardening off” your seedlings before transplanting them into the garden. This process is necessary for helping indoor seedlings grow accustomed to outdoor conditions by gradually exposing them to daily shifts in temperature, light, and water. As you prepare your seedlings for transplantation, read your seed packet to determine when you should transplant them outdoors, as not at all crops tolerate frost. 

On behalf of the Garden Tower Project, here are some general guidelines to help your seedlings get off to the best start.

5 Steps for Hardening Off Your Seedlings

Steps for Hardening Off Your Seedlings

  1. Begin the hardening off process 7-10 days before transplanting outdoors. 
  2. Start by placing your plants outside in a shady area protected from wind for 1-2 hours a day for the first 2-3 days. Bring them back inside at night.
  3. For sun-loving plants, begin putting seedlings in the sun for longer hours at a time for 2-3 days. Make sure you avoid harsh mid-day full sun exposure. If the plants you are hardening off are shade or part-shade plants, leave them in the shade or dappled sunlight. Do not put seedlings directly in the path of wind, as they may dry out quickly or snap.
  4. After 7 days, your sun-loving plants should be ready for full sun and can stay outside at night if nighttime temperatures are above 45°F. When caring for cool season crops in small containers, err on the side of caution and bring them back inside when it is below 45ºF. Cool season crops like broccoli, lettuce, greens, and cabbage can handle colder temperatures when planted in the ground.
  5. After 7-10 days your plants are ready for transplanting. To reduce the stress of transplanting, transplant in the evening, or on a cool, cloudy day. Water plants immediately after transplanting. A diluted dose of kelp or seaweed fertilizer also helps prevent stress. Keeping plants protected with row covers for another week will help them adjust to their new home and protect them against fluctuating temperatures.

For more tips on gardening and planting, visit the Garden Tower Project blog today!


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