How to Properly Transplant Seedlings
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When growing plants from seed, generally, you start several seeds in a small space such as a seed starting pots or sheet pots. Because of this, when the plants start to germinate, they are overcrowded and need to be thinned out. Naturally, not all seedlings are going to survive to maturity, it is for this reason, most people start more seeds than they need or want.
The plants that do survive, go on to be the mature plants that you harvest produce from or shape into bonsai. In order to ensure some of your planted seeds make it to the stage of mature plant, you will, at some point, need to transplant the plants when they are seedlings. It’s not as simple as just transferring them to a new pot, there are many considerations and steps involved in the process.
Why Timing is Important
Seedlings, because they are young and not firmly established, are more sensitive to being disturbed than mature plants. Transplanting a seedling is one of the most disruptive things you can do to them. It’s an unfortunate situation as, seedlings need to be transplanted at some point; however, it’s one of the most stressful things they can be exposed to.
Due to the stress induced from transplanting (known as transplant shock), the timing in which you choose to transplant your seedlings is critical. If seedlings are transplanted too soon, the stress can overcome them. Transplanting them too late can cause the seedlings to have stunted growth and, if they are crop plants, can be detrimental to your crop yield.
How Root Development Ties In
Only the tips of roots absorb nutrients, the rest are incased in wood or tissues that are turning into wood (known as cell differentiation)! That’s right, roots have wood! While this is a slight oversimplification of root botany and nutrient uptake, roots, even when branched, are only able to absorb nutrients from the growing tips. This means that sections of root that are further from the growing tips, cannot absorb nutrients with any real efficiency.
As the plants roots grow further and deeper into the soil, smaller root-like structures grow out of the roots. These fine filamentous structures are known as ‘root hairs’. Their primary job is to absorb water from the soil to be transported up the plant through the vasculature (the plants xylem). So how does all of this tie into transplanting seedlings?
When uprooting plants, as you must to transplant them, they must be removed from the soil. During this removal, if the growing root tips are compromised and destroyed, the remaining root mass will not be able supply the plant with the needed water and nutrients to survive the transplant. If this happens, the plant will become stressed and gradually perish.
For this reason, it is very important to ensure the roots are disturbed as little as possible during the transplant. Protecting the plant’s roots will give the plant the best chance it has to overcome transplant shock and resume its growth quickly.
Different Forms of Transplanting
Transplanting seedlings is usually done either to separate the seedlings that are crowded (usually after planting the seeds and the plants seedlings have grown a bit), or to transplant seedlings to the outdoors, such as a garden bed or larger planter. Regardless of whether you’re transplanting tree seedlings destined to be Bonsai or vegetable starts for produce, the general process that follows is the same.
Step-By-Step: How to Safely Transplant Seedlings
In order to safely transplant your seedlings, there are a few things you can prepare beforehand to ensure the process is as smooth and un-stressful as possible. There are also a few tools that can make transplanting simpler.
Step 1: Preparation of New Planting Location
First off, you need to make sure your seedlings are ready to be transplanted. As the roots of the seedlings grow, they will eventually begin to encircle the pot they are in, this is the beginning of the plant becoming ‘root bound’. Another good indication of seedlings being ready for transplant is when there are roots coming out of the bottom of the pot.
It’s always a good idea to prepare the new planting location whether that be a single pot, sheet pot, or your outdoor bed or planter. Ensure that the new pot has some of the new planting media in it (about half full, depending on the size of the pot). If you’re planting outdoors, ensure there is a hole big enough for the plant to be planted in.
This is a good time to include additives to your new planting location. For example, adding things to help the seedlings grow such as mycorrhizae and fertilizer (organic or synthetic) will help encourage new root growth.
Step 2: Prepare the Plant For Transplant
To prepare your seedling for transport, take the pot and gently squeeze the sides to loosen the soil. You’re looking to have the soil and the seedling to come out in one piece. This is to ensure the roots are disturbed as little as possible. If you have a small soil plug with multiple seedlings in it, getting the plug out without disturbing the soil should be much easier.
Depending on how densely your seedlings are planted, you’ll likely find that some of the plants haven’t grown as much as some of the larger seedlings. It’s normal to lose some of your smaller seedlings as they’ve not been able to establish themselves. You can attempt to save these little ones; however, it’s quite common for these weaker individuals to not make it.
Step 3: Gently Tease the Seedlings Apart
As we covered earlier in this article, in order to cause the lease stress to your seedlings during transplanting, causing as little damage to the roots as possible is important. As you work to tease apart your seedlings, work slowly and try to avoid breaking as many roots as you can. To make this job easier, make sure the soil plug your seedlings are in is wet. Wet soil will allow the roots to be teased apart easier than dry soil.
Once you have your seedlings removed from the soil plug and the roots teased gently apart. You should work as fast as you can to get your seedlings planted in their new planting location. If you’re working with multiple seedlings, it can make sense to tease them all apart, set them somewhere safely and continue working on the rest. Wet soil will also help to reduce the speed your seedlings dry out.
Step 4: Planting Your Seedlings and Finishing Up
At this point, your new planting pots or beds are prepared for your seedlings and the seedlings themselves have been separated and are ready to be planted. It’s time to plant your seedlings in their new growing location.
The best way to plant your seedlings is to set the seedling on top of the new soil while still holding it to keep it upright. Add more of the new soil media around the roots of the seedling. While adding soil around the roots, gently shake the pot or planter, if planting into a garden bed, gently shake the seedling near the roots. The goal of shaking the pot or the roots of the seedling is to ensure soil media moves into the spaces between the seedlings' roots.
Keep filling soil around the seedling until the roots are all covered under the new soil media. Gently press the soil down around the seedling to help with the upright stability of your seedling. Some seedlings will need extra support such as a trellis, stake, or wire (mainly for bonsai seedlings).
The last step is to thoroughly water your newly transplanted seedlings. Once all the transplanted seedlings have been watered, they are ready to begin the accumulation period to their new growing location!
How to Properly Transplant Seedlings, Wrap-Up
When it comes to transplanting your seedlings, there are a few things to keep in mind. The timing of the transplant is important, too early and the plant may succumb to stress and die, too late and it can stunt the growth of the plant. The roots of the seedling need to treated as gently as possible so as not to damage them.
The new planting location, whether new pots or garden beds, should be prepared prior to the transplant. This includes getting the new soil ready and additives added. Next, you’ll need to prepare the seedlings for transplant by separating them out and gently teasing the roots apart. Lastly, the seedlings are to be planted in their new location. Making sure to shake the soil media into the spaces between the roots of the seedling and pressing the top of the soil down to help your seedling stay upright.