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You got the seeds to germinate and have been fussing over those seedlings for weeks. Protecting them from drying out, being too wet, curious pets, “helpful” children, and now is the moment of truth… planting those plant babies.!

It’s like sending your kid to college in the big bad world!

How are those plant babies going to cope?

Will something terrible happen to them?

Will they thrive?

Yet, despite all the worries, the anticipation of watching them grow kicks in.

Perhaps you find yourself paralyzed as we arrive to plant out those little guys.

Do I need to do anything before planting them out?

Do I need to put them under a tunnel?

Do I feed them?

The list of questions goes on!

In this post, we will discuss all the details of successfully transplanting your seedlings without them skipping a beat!

We will be covering the following:

Proper seedling size for transplant
Handling the seedling pre-transplanting
Preparing growing bed soil for the seedlings
Deciding when to plant seedlings
How to transplant seedlings
Warning signs to look for and how to address

I want to preface this by saying two things:

Plants want to grow; we have this in our favor.
The elements we think will be the most detrimental to our seedlings are often not the reality of what gets them.

Seedling Size for Transplant

There is not a technical “best size” for transplant.

The seedling size being able to handle transplanting will depend on:

Variety needs
Weed and Pest Pressure
Soil Type and Watering Infrastructure

Balancing Robust Root System and Root-bound

Many growers, especially newer ones, are shocked to discover how tiny a plant can be transplanted successfully. A majority of our varieties are planted directly from 128s. More than looking at the size of the seedling from the top, we are more concerned with its root system. Most cut flower varieties tend to get fussy with their roots being bound, stunting the plant’s growth. As a flower farmer aiming for luscious blooms atop long stems, stunted plants are far from desired.

We determine when a seedling is ready by how easily it pulls out from the cell by its true leaves. If it comes out without us needing to scoop it out with a butter knife, it’s ready to be planted. We balance planting the seedling while its root system is developed enough to hold the soil together before getting root-bound.

Weed and Pest Pressure

There are also differing microclimate challenges that may determine what size is best for planting your transplant. For example, if you have slug pressure, you will probably want larger poppies (72-50 or 2-inch soil blocks) to survive the slugs. If you have a lot of weed pressure, planting transplants later may help them avoid being choked out by the weeds.

You will probably not want to plant seedlings smaller than 128 if you have significant weed or insect pressure. If what I am saying with all these numbered cells has you scratching your head, check out our favorite seed supplies, which we explain further here.

Soil Type and Watering Infrastructure

When we first moved to our current property, the area where our flower field now flourished was rather dead—decades of being treated with herbicides and pre-emergents before that being compacted by livestock. We are also in a high desert with rocky, clay soil that is low in organic matter and difficult to hydrate. It has been brought back to life after six seasons of pampering and growing in the soil!

In those early seasons, though, larger seedlings transplanted better for us as their root systems were stronger and could be planted deeper into the ground, which meant less of a chance of them drying out.

For soil with low organic matter and moisture, it is essential to use drip irrigation and water in the seedlings by hand. Yucca can also help with the plant’s water uptake, as it is used as a soil amendment or a monthly drench.

Before we get to the task of transplanting the seedlings, we must best prepare them for the elements.

Handling Seedlings Pre-Transplant

The manner in which you prepare your seedlings for transplant could look different depending on your seedling growing setup. Handling the seedlings prior to transplanting is really important to prepare them for growing out in the field or even high tunnels.

Hardening Off Seedlings

The method of preparing seedlings for transplant often involves “hardening off” the transplants. Hardening off is when you gradually introduce the seedlings to the elements they will be facing before the shock of transplant in their new soil.

During this phase, you risk losing your seedlings to a crispy death, or if done correctly, you will best prepare them for transplant!

The elements you will be introducing your seedlings to are:

Sun exposure
Wind
Temperature Fluctuations

For us, they are growing in our little propagation house, which is in full sun. We also have a fan set up in there to keep the temperature down, but it also does something else… it prepares our seedlings for wind! Though we have a small heater in the propagation house, it really is just enough to keep it above freezing, not incredibly cozy…which helps prepare them for colder conditions.

All of this better aids our seedlings in handling natural elements. Often, our seedlings go straight from the propagation house into the field without any additional hardening. Once our propagation house starts getting too full, depending on how on top of planting out we are, we may have older seedlings on our overflow table outside of the propagation house.

Though I’m a huge fan of our little propagation house, I also understand that’s not everyone’s reality: bootstrapping what we have available to start plants and making it work is the name of the game.

Often, this will look like indoor growing in a spare room, basement, garage, or a sunny kitchen window sill. Perhaps you’re fortunate enough to have a vertical seed propagation system.

For seedlings started indoors, it is especially important to harden them off since they have not been subjected to natural sunlight, cold, or wind. This will start at a young seedling phase.

| PREPARING SEEDLINGS FOR WIND |

Preparing your seedlings for wind should be started at a relatively young age. Seedlings will stretch and become fragile for two reasons: low amount of light and being cozy. A leggy (stretched) seedling can struggle when transplanted. As mentioned, we expose our seedlings to wind since we have a fan that blows through. We also “pet” our seedlings.

Running your hand over those seedlings (petting) or setting up a fan to gently blow on them will help prepare them for that wind and help them grow stronger and less leggy. When placing a fan on seedlings, be sure to have it lower and on rotation to keep them from drying out too much or getting windburned.

| PREPARING SEEDLINGS FOR TEMPERATURE FLUCTUATIONS |

The cold is what a typical plant parent worries the most about, and not without good reason. Many of us have grown tender annuals, such as tomato plants, that are incredibly frost-sensitive. Having transplants freeze is a concern, but not as much as what too much heat can do to a seedling that hasn’t been properly transitioned. I have had seedlings freeze, but if they are a hardier variety, they do tend to rebound or begin to shoot out new growth. Even tomatoes that have been kissed with a late-season frost tend to rebound okay. We are not strangers to a summer solstice hard frost in our climate!

On the other hand, if the heat damages the transplants too badly, I find it rare that the seedling rebounds.

Part of the reason we keep our propagation house minimally heated is to better prepare the seedlings for the cold. Even a cold-hardy crop can get cold-damaged from light frosts if the tough hasn’t been exposed to cooler temperatures. Many cooler growing varietals also benefit from a cycle in temperatures from day to night, such as larkspur.

On the other hand, we also need to keep the seedlings from getting too hot during the day. When the seedlings grow in trays, they must contend with soil temperature swings more than when growing in the ground. We also have fans to keep seedlings from getting too hot. Growing indoors and using lights, moving the lights to keep them from being too close to the seedling, and not using the heating mat once germination has occurred can keep the seedling from getting too hot and stressed.

We must prepare the seedling for one last element, which is also the most dangerous to tender seedlings.

| PREPARING SEEDLINGS FOR SUN EXPOSURE |

Using proper grow lights and having them the proper distance away from the seedlings to keep them from stretching will give your seedlings a great head start in preparing them for transplant.

Even with quality grow lights, the seedlings must be introduced to direct sunlight. If your seedlings are leggy, you must be incredibly diligent about keeping them from getting crispy or too wilted.

Introducing seedlings to sunlight:

Before leaving your seedlings out in the direct sun unattended, be sure to do the following:

Water your seedlings thoroughly
Place seedlings in a protected area, preferably shaded, to start the process.
- If you can, choose a cloudy day with no to minimal wind.
Begin the process, preferably in the morning when the sun is less harsh.
- Let them be in the morning sun and check on them every 10-15 minutes.

As you leave the seedlings out in the direct sun be sure to:

Keep a watchful eye for signs of wilt, once you spot it bring them back inside. This is a process where you really don’t want to take your seedlings out at the beginning of the day and leave them out for hours while you’re gone. It takes some diligence.

Increase sun exposure a little more each day. The amount of time will depend on how your seedlings react.
- If they aren’t showing signs of wilt or yellowing, continue allowing them to be in the sun.
- If they show signs of wilt, bring them back in the shade or indoors, give them time to perk up, and try again.
- Increase exposure in increments of five to fifteen minutes. You are the plant parent; use your best judgment!

Depending on your seedlings and setup, exposing them to the sun can take a few days to more than a week.

Some things to keep in mind:

As mentioned earlier, the soil temperatures in propagation trays are more extreme than those of the growing bed. The soil in the propagation tray can get hotter or colder, whereas the soil in the field will be more consistent with less fluctuation.
- If you use small-celled trays or soil blocks, you should know that the soil will dry more quickly.

If seedlings seem unhappy, ensure they are well watered, and then give them a dose of Fox Farm’s Big Bloom or heavily diluted kelp to help them recover.
- Phosphorus helps when plants are stressed. Avoid feeding them nitrogen, such as fish emulsion, while they are stressed.

Now that you know what it is and how to harden off seedlings properly, we need to prepare their new home!

Preparing the growing bed for seedlings

Preparing your growing bed is a whole series of blogs in itself, but I am going to touch on it briefly for now.

Your soil health is number one.

Trust me, we learned this the hard way. If you want to hear that story and what we learned from those mistakes, watch our video here or at the end of this post.

I cannot emphasize enough the importance of getting a soil test done, ideally you want this in the fall but you can also do it in the spring. Pay the extra bit of money to get the recommendations from the lab on what to amend your soil with. You may be surprised, as we were, that the “quality compost” (there seem to be many different definitions of “quality compost,” be warned!) actually hurt our plants. I mention this because nutrient deficiencies/lockout, poorly amended soil, or salty compost can all have similar signs as seedlings coping with difficult weather (too cold, windy, too hot), lack of water, too much water, transplant shock, or even poorly transitioned seedlings.

If you properly hardened off your seedlings, they were perky, green, healthy, and properly watered, and then a week later, they were yellowing and dying. Still, they had been properly watered, and the weather behaved… take a second look at what you did with your soil prep. If seedlings aren’t thriving and the weather is not adding up, I recommend trying a yucca flush to see if that helps. If it does, you have some soil problems.

We lacked nitrogen and organic matter for our soil needs, and our soil leaned a little to the heavy clay side. For four years, we amended our soil with basic compost from a reputable company (only about an inch). We also amended our soil with humic acid, powdered gypsum, and a pre-plant mix (which slowly breaks down), and on newly opened rows, we do rock dust initially, but that’s a one-time amendment for newly opened beds. These days, we only compost with our own compost, primarily garden waste, along with the slow-release fertilizer.

The biggest thing we did for the health of our soil was to grow in it. Also, during the winter months, we cut down the plants but left the roots in the soil to continue feeding all the beneficial worms, nematodes, and microbes. Sometimes, less is more when it comes to soil health.

Once the soil is amended, whether you prefer till or no-till methods, we have a couple of ways we have prepped the rows for efficient planting that will lead to the transplants growing wonderfully.

How To Transplant

When you are ready to transplant your seedlings, be sure to:

Have hydrated seedlings
Water the growing bed, before and after transplant.
- We run the irrigation and hand-water
Transplant during the cooler part of the day
Wear gloves
Protect your knees with knee pads (if kneeling on the ground)

The Importantce of Planting Straight

Over the years, we have experimented with various ways to plant out. In the first years, I hazardly planted the seedlings in between toddlers napping. Crooked galore!

I was content with just getting done with the task… until my crooked planting resulted in the seedlings not being evenly watered, and my frustrated husband tried to weave drip tape between my sloppy planting.

To combat my crooked planting and ensure the transplants would be properly watered and our bed space would be optimized, we used three different methods over the years:

T-stick and String line
Drip Tape Emitters
Landscape Fabric with burned holes

T-Stick and String Line

The first couple seasons at our current property, we were still in the throes of opening up growing beds and installing irrigation. Planting season would come upon us while my husband was drowining in tax season, yet I had plants to get in the ground and orders to fulfill.

We had to compormise.

Not ideal, but we used to the T-stick and string line, which allowed us to plant with or without drip irrigation in place. If the drip tape was not laid down, the plants were perfectly pl;aced and planted to not impede easily putting the drip tape after.

The “T-Stick” is a couple pieces of scrap wood, the top of the T is the width of the growing bed where we marked our spacing. We then strung baling twin down the center of the row, which we used to keep the T-Stick centered. Along the outer edge of the growing bed we had a measuring tape to be able to space out seedlings.

Now, this method worked in a pinch. Some downsides are that it can be time consuming to set up the center string line to get planting. Another down side is that if the wind pickups, the line moves which can make keeping the T-Stick centered difficult.

Using Drip Tape Emitters

The next evolution of our transplanting came with using the drip tape emitters to space out the seedlings. We use eight inch emitters. Overall, using the drip tape isn’t horrible. It ended up being much quicker than the T-Stick and String line method. Looking for the tiny emitters still wasn’t the most efficient and we did find that helpers often would plant crooked. In a pinch, it works and we still use it but last season we found our preferred method.

Using Landscape Fabric

After years of working on our soil health, we now grow not only healthy plants but also lots of weeds!

So, last season, we bit the bullet and invested in landscape fabric. We pre-burned the holes and laid down the drip tape before laying down the landscape fabric. In the name of further efficiency, we use a large auger on our drill rather than hand digging out the holes for the plants to transplant. With two people, we can have one of our standard 45-foot rows planted, with our normal spacing of 7x7, which is 385 plants, in about twenty minutes.

Some other methods for spacing out transplants growers use may be using their hortonova trellising.

With your seedlings prepared for planting and beds prepped, you may be wondering when to plant them out.

Deciding When to Plant Seedlings

A quick mention of the difference between a commercial flower farmer and a hobbyist: we push the boundaries as flower farmers. Our biggest but most profitable gamble is those shoulder seasons, spring and fall. The sooner you get your product out and the longer you can offer your product, the better sales you will have, not just because of having a longer season, but also because we also find the highest demand for our flowers is on those shoulder seasons.

In our area, we can go from winter straight to summer. To have enough crops come spring, we push planting out early and utilize season extension methods. Remember, your hardiness zone tells you what you can overwinter, and your frost date range tells you when you can plant. We refer to frost dates as a range because different crops will thrive or die at certain temperatures.

As flower farmers, we do not work with an average last frost date. To learn more about that, read or watch a video on Demystifying When to Seed Start here.

We determine when to plant out the seedlings based on three things:

The weather forecast
Soil Temperatures
Volunteers germination in the field

Weather Forecast

As a flower farmer, you will be more knowledgeable than the weatherman!

We check apps multiple times a day, and honestly, we watch those mountains. If the clouds look moody, we know we’re probably in for some high wind. Try to plant out on a calm, cooler day. If there are storms in the forecast within the first week of planting those seedlings, plan on protecting them with low tunnels. It takes a good week or two in the winter for those seedlings to establish. High winds and such will make it tougher on them or potentially kill them. Even with protection, you may see some casualties or damage to the plants. Most plants will recover, but looking at them might make you panic a little for a couple of weeks.

Soil Temperature

Another tactic we use to determine when to plant out is to check the soil temperature. I’m not usually this diligent when it comes to protecting my cold, hardy crops from volatile winter and spring weather. Still, for our warm-loving crops, I want to see soil temperatures above 60F, which is the active growth temperature for most plants.

Volunteers Germinating in the Field

If you have been growing on your property for some time, you may already know this next tactic. We also look at volunteers who decided to germinate. At this moment, we have insane amounts of Queen Anne’s lace under a tunnel and violas, and Atriplex is everywhere. I also see salvia and Iceland poppies, which tells me the soil temperatures are ready for some transplants.

How to Transplant

Using your spacing and planting out method, tuck them into their growing beds.

Okay… that was lame. Let’s dive into a little more detail!

When transplanting, proper spacing and utilizing those methods are important.

Here are some additional tips to go with that:

Plant seedling level with the soil
- Some varieties benefit from being planted deeper and will root from the stalk, such as tomatoes, though this isn’t typical for most varieteis
Smooth out the soil after for proper permeation of the water
Try not to fuss with the roots too much, especially for the ones with a long tap root or that are sensitve to roots being tampered with such as ammi or celosia.
Hand-water in seedlings after planting
Place a micro-tunnel, made with frost cloth and galvanized wire found in the fencing supply section, over transplants to help them better transition.

Troubleshooting Failing Transplants

The idea is that hopefully, by executing the various tips we provided, troubleshooting won’t arise but just in case watch out for:

Yellowing
Crispy
Wilting
Damping off
Purpling

It is tricky to say what exactly can cause any or all of these issues.

It can be anything from transplant shock, weather, lack of water, too much water, disease, soil troubles, fertilizer/herbicide/pesticide damage, or a combination of these issues. This is where watching closely, taking notes, and playing detective will help. The reality is that you are the one who knows every step in your plant’s journey. You are in the trenches, and you really are capable of deciphering and resolving issues that may arise. The biggest thing is to stay positive and calm.

If a plant looks really suspicious, sending in a tissue sample to your local university or working with your department of agriculture can help.

In general, if you see some yellowing or wilting in transplants for the first few days to a week, it is usually due to shock. If you are losing seedlings, you will want to take further action.

What to do When Seeing Problematic Signs

First, don’t panic. Have faith in your plants and let’s get to work resolving it the best we can!

Increase water, if under watering and plants look crispy (soil is dry to touch)
Decrease water, if overwatering and plants are yellowing (soil is soggy and is even starting to smell like ammonia, have fungus gnats or algae growth).
Yucca flush can help with any of the above problems. It helps flush the soil of salts and helps plants be able to better uptake water. It is an incredible tool to have in your arsenal as I find it aides plants so well in general, especially is growing in an arid climate.
Properly vent tunnels in case they are cooking the transplants
If purpling, it may be a phosphorous deficiency or cold damage. Note, some varieties naturally purple like some colors of snapdragons. Consider frost protection if not using and seeing symptoms of cold damage or feed kelp or Big Bloom if concerned about too low phosphorous.
If you have frost damage, I would say pinch back the plant (if a branching variety) to have the plant refocus its energy into sending new growth. If it is a cold hardy crop, it will most likely bounce back bigger and better! Just as mentioned in my sweet pea story.
If you are seeing dampening off, you may have soil pathogens causing that. It could be in your growing soil or it could have been present in your seedling substrate if you chose one that was not soil-less (had compost or garden soil). Send in soil sample and watch your other seedlings, re-evaluate substrate choice for a soil-less one if seeing dampening off with your other seedlings.
Soil test, if you haven’t already and are seeing seedling lack of thriving send on in.
Take photo of seedlings, use good old google image search to begin your own investigation. Research individual plant needs/disease/pest issues
Plant tissue analysis from department agriculture/local university is still seeing seedlings lack of thriving.
If the plants are truly not thriving, pull plants out and try again. If you are concerned about soil problems more than it being the plants themselves, throw some squash or bachelor buttons in there… they aren’t picky!

Transplanting is truly more intimidating in theory than actually implementing it. However, you will soon be holding those armfuls of beautiful blooms you worked so hard to grow!

I hope this post helped to answer some questions and give a little peace of mind when it’s time to boot those plant babies out into the big bad world of a field!

Remember: the plants want to grow, and with a bit of our help, they will thrive!

Until next time…

We are looking forward to helping you hand blooms soon!
Jessica & Graham

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Nitty Gritty: Transplanting out seedlings