harden off plants

Harden off plants involves some actions that need to pay attention, You might have a doubt why hardening important to me, how it is done, what are the risk points, I thoroughly believe this article provides you the all conclude information about hardening plants.

What is the Harden Off Mean?

As a reader of this article, you may have grown or expected to grow plants in your greenhouse, grow lightbox, growing rooms, under shedding net, in a cold frame, or else buy some plants from a plant nursery. However, plants need some time to adapt to the environment conditions gradually. Plants need a properly train or ready before transplant them in the actual environment. This process is called Hardening off & it is a type of artificial shock give to your plants

What we are doing to this transition period is called “Hardening Off”. Before that, I think that it is useful to know the importance of Hardening off, then approaches to hardening off.

Why Hardening Of Seedling is Important?

You know that small plants cannot get high sunlight or rain even the wind. So based on the plant type, based on the plant category you are going to transplant they should be ready to bear the environmental condition out there. Otherwise, plants will wilt, grow slowly, or stop growing. Further, it won’t be able to take manure effectively and cause to lower harvest, or died in untimely. 

You might have a problem that does every plant need hardening. My answer for you is “hardening is not necessary for all plants”. You are not expecting a slow growth, a weak plant after you transplant it, Instead of that you hope a plant has the optimum growth, quality plant. So Hardening of the plants important & need to take steps to acclimatize them to their new outdoor home. Otherwise, you are in a risk of losing your plants and wasting all of your hard work. Following some of the important things to figure out. 

  • Hardening off will improve the plant quality.
  • Plants that are well hardened can resist to loss of water. 
  • Dry residuals in the plant will increase due to hardening.
  • Hardening will balance the growth rate of your plants as you wish.
  • Hardened plants have the capability of surviving harsh weather conditions.
  • Hardening help to continues the transpiration process without damage to the plant.
  • Cause to accumulate more carbohydrates reserves & produce additional cuticle on the leaves.

The hardening of seedlings makes more strengthening to withstand in unfavorable conditions as a new seedling. These conditions are hot, dry wind, low & high temperature, etc.

How to Harden Off Plants: Three Approaches

There are three approaches/shock to hardening of plants: Steps in Brief, 

  • Train them to outside conditions – Exposure to the full sunlight  
  • Uncover cold frame – Removal cold frame cover, polythene sheets
  • Withholding water – Control irrigation 

#Train Them to Outside Conditions 

harden off plants

You can use an unheated greenhouse or shade outdoor area for this work. However, we cannot directly put them outdoors and see what happens.

Simply you can place seedling or plants shorter time for the first day & gradually increase the length of time within the next few days until the transplant day. This approach we mainly trying to prepare your plant to bear the sunshine.  After seven-eight days, seedlings can be left outside overnight, so long as there’s no danger of frost. 

My Recommendation

This is what I did to succeed in the hardening off. Normally hardening off process takes before 7-10 days before the transplanting date you need to start slowly this process. If you expose them to high sunlight, it will burn quickly.

Find a shady place (Under a tree, car pouch, and backyard) in the outside and have a schedule, however, I normally grow medicinal plants that are not as delicate as vegetables & ornamentals flowering plants. 

The first day I keep one new plant, which never I tried before. Then I usually monitor the plant, whether my schedule is suitable for that plant types. If it okay to me I bring the all other seedlings and gradually increase the time that to keeps in outside. 

The plant needs to bring back into the net house, greenhouse, or warmth indoor in the nighttime.  

After 2-3 days, move the plants into the morning and return them to shade at the noon. However, After 7 days the plant should be able to stand and bear the sunlight for the whole day and stay out at night. Within 7 days if I can’t see any good results I do follow the schedule for two or three days more.

Following schedule might help you to harden off your plants well, Hardening off at least begin before 10 days

My schedule for hardening of seedling:

1st day Place your seedlings in a shady place for one hour, in the morning hours.
2nd day Keep your seedlings for 30 minutes under morning sun & 1.5 hours in the shade. 
3rd dayKeep your seedlings for 1 hour under morning sun & 2 hours in the shade.
4th dayKeep your seedlings for 2 hours under morning sun & 2 in the shade. 
5th dayKeep your seedlings for 3-4 hours under morning sun & 1 in the shade.
6th dayKeep your seedlings for 6 hours under sun & 1 in the shade if needed.
7th dayKeep your seedlings for 7 hours under sun & overnight in the outside.
8th dayNow your plants may be well hardening off keep it for a whole day outside.

#Withholding Water

harden off plants - Withholding water

By withholding the water, we expecting to increase the ability of seedling to bear or survive even in the minimum water level.

Withholding water can be started before two weeks of transplant date. First, stop your water supply for the seedling until it shows wilting signs. After you see plants are going to wilting don’t keep them for a longer time.

Don’t take too much time, supply water again, and continue the same process during the two weeks.  Only withholding water is not sufficient for the success of your hardening process. Train them to bear hot weather conditions. Both withholding water & train to outdoor together will cause you to fail in this process.

#Hardening Off Plant in Cold Frame

harden off plants - cold frame

Same as the first method this takes 7-10 days before your actual transplant date & the same effect can be achieved opening & closing the lid of the cold frame. This method especially can be applied to the seedlings that are grown indoor under controlled weather conditions like greenhouses or Cold Frame.

We can move them to the outside or keep in a cold frame to the hardening of seedlings. You can turn off the heater or open the lid of the cold frame instead of moving to the outside. The time of the period can be increase gradually. 

Start this by opening the cold frame for 3 – 4 hours on the first day and keep opening 1-2 ours additionally in the next few days.

In the night time close the cover of the cold frame. Your hardening off will be a success within 7 -10 days.

Tips for Hardening Off Success

One of the most considerable aspects should be sunlight. If your seedling shows signs of difficulty to bear keep them in a shaded place & change the schedule.

It’s important to aware that we should not place where birds, snails, insects have a chance to damage them during hardening off.

If you purchased plants from another supplier or plant nursery (if they were sheltered for a longer time) make sure to harden off them as well.

Don’t force this process too much and expected results too quickly it will take some time to adapt to the outer environment.

You can try a sample of hardening before you put out all of your stock at once. When they ready to transplant them in a cloudy day & wall water them.

If your outside condition too hot make sure to watering your seedling before exposure to the sun. Because if you going to tender plants to harden off they will not be able to bear the conditions.

After hardening Off – Ready To Plant

hardening of seedlings

When you have done the hardening off successfully now you can plant them in your garden or a pot. However, keep your attention on it still have a chance to transplants shock.

It can be due to the carelessness of transportation, movement, or changing the conditions were exist. So make sure to move your hardened plants safely without damaging them to where you expect to plant them.

To avoid that kind of transplant shock to hardened plant you can do, moisture the soil by water the pot before you remove it, moisture the dig you expect to place them, don’t remove soil around the root.