How To Thin Petunia Seedlings

Take a close look at the seedlings. Which ones are the healthiest? The ideal seedlings to continue developing are those with short, sturdy stems and their initial real leaves, which are the second set of leaves produced by petunias.

Petunias in seedling pots should be thinned until just one seedling is left in each pot. Petunias in trays should be thinned so the remaining seedlings are roughly two inches apart from one another in all directions.

When can petunia seedlings be transplanted?

Petunias are simple to grow outdoors from transplants, but starting them from seed may be more difficult for novice gardeners. The benefits of starting petunias inside include a greater selection of types and the ability to grow numerous plants at a reduced cost. But petunias need to be started early because it takes 10 to 12 weeks for them to grow large enough to plant out (about March first in northern climates). This means that there is a lot of room for issues to arise between seeding and the finished result!

Petunia seeds are difficult to handle because of their size, even for seasoned gardeners. They are extremely little and delicate, and they require light to germinate. While easier to handle, pelleted seeds aren’t always readily available.

  • Sparingly scatter seeds over clean, wet potting soil or ground sphagnum moss.
  • Before watering, press them gently into the potting soil with your fingertips or use a light mist of water to wash them in.
  • Until the seeds start to sprout, cover the container with transparent plastic and keep it in a sunny, warm (70 to 85 degrees F) location out of direct sunlight. After planting, this typically takes 7 to 10 days.
  • Once the seedlings have emerged, remove the plastic wrap.
  • Place the container in a light, but cooler area with temperatures between 55 and 65 degrees Fahrenheit at night and 65 degrees Fahrenheit during the day.
  • Until they are ready to be planted outdoors, place the petunias 4 to 6 inches beneath a fluorescent light lamp.
  • You are not required to purchase pricey lights designed specifically for growing plants. Typically, standard fluorescent tubes work just well.
  • To keep the lights on for 16 to 18 hours each day, set a timer.
  • As seedlings enlarge, raise the lights while continuing to keep a 4- to 6-inch distance between the plants and the lights.
  • It’s time to transplant seedlings into separate peat pots or packs that each hold multiple plants after they have three genuine leaves.
  • Feed them with diluted liquid fertilizer every two weeks (weekly for the “spreaders”).
  • By putting young plants outside on warm, bright days, you can harden them off. After a few days, bring them inside at night before permanently planting them outside.

How should seedlings be thinned?

Use garden snips or a scissors to thin out crowded seedlings. Nobody enjoys thinning out seedlings. Making the decision of which to keep and which throw is tedious work. Here is a quicker method: Snip the additional seedlings off at the soil line as soon as the first genuine leaves show.

I have seedlings, when should I begin to thin them?

When seedlings have one to two sets of genuine leaves, they are typically trimmed. The plant is not viable until the next real leaves grow, which will have a very different appearance from the first leaves, known as the cotelydons. The first leaves are embryonic seeds contained in the seeds.

Most plants reach a height of 2 to 3 inches when their first true leaves appear, at which point they are easily pulled out by the stem. After watering, you can thin your seedlings to make it simpler to pull them without disturbing other seedlings if you’d rather pull them than cut them with scissors. Additionally, it’s best to thin in the late afternoon so that the surviving seeds have time to acclimatize overnight before being exposed to heat and sunlight.

How can seedlings be thinned without destroying them?

It can be challenging to imagine the proper way to thin seedlings at times. As a result, I decided to outline the process in plain English for you to follow.

I used a lot of photographs because I, like some of you, learn best visually. Here are the straightforward, step-by-step directions.

Step 1: Select which ones to eliminate

After keeping the strongest seedling out of the group, thin out the others.

Find the one that is most compact and has the thickest stem if you want to choose the strongest. Simply choose the one that looks the nicest if they are all the same size.

Step 2. Use the right tool

For this delicate work, regular pruning shears are far too big and unwieldy to use, and it’s possible to unintentionally harm the other seedlings in the process.

Therefore, for fine cuts, I suggest using bonsai shears or a little micro-tip snip. Additionally, make sure you clean the blades first. Simply put them into rubbing alcohol for that purpose, or wash them with soapy water.

Step 3: Remove the base of the weak seedlings.

Cutting the stems off at the base rather than pinching them off is crucial.

And when thinning, never attempt to remove the seedlings from the ground. By doing that, you risk killing the others as well as harming their vulnerable roots.

This is crucial for root crops in particular. When plants are young, root injury is one of the main causes of malformations.

4. Fertilize the last of the seedlings.

Give the remaining seedlings a squirt of fertilizer for an added boost when you’ve finished spacing them out properly.

Use starter fertilizer or experiment with compost tea (which you can get in liquid form or buy tea bags to brew your own). Fish emulsion or liquid kelp are other favorites of seedlings.

How To Pick The Strongest Seedling

Locate the group’s healthiest and most compact seedling to choose from. The one you want to keep is that one. Then reduce the number of others.

If they all appear to be in good health, remove the smallest or weakest-looking individuals. Just remember that tall people aren’t necessarily the healthiest.

When they don’t get enough light, they become tall and lanky. Therefore, get rid of any that appear weak or scraggly.

You can just thin the seedlings at random if they are of the same size. Alternately, wait a little longer to see if one of them grows to be larger than the others. However, you really can’t go wrong in this situation, so snip away.

How Much Thinning Do I Need To Do?

If your seedlings are inside, you should trim them out until each cell, pellet, or pot has just one plant.

This will not only offer them lots of area to expand, but it will also make transplanting them into the garden much simpler.

The spacing guidelines on the seed packet should be followed when thinnng seedlings that were started outdoors rather than indoors.

Is it necessary to thin out petunia seedlings?

In the summer, annual petunias add color to flowerbeds, pots, and hanging baskets. The seeds, which are typically planted indoors six to eight weeks before to the last spring frost, grow quickly into plants. To acquire the appropriate number of plants, it is important to spread additional seeds because not all of the seeds will germinate. Petunias may not develop well if numerous seeds germinate in a single container because the young seedlings’ roots fight for moisture and nutrients. Additionally, seedlings that are crowded are more vulnerable to fungi. Healthy seedlings for late spring transplants are ensured by thinning the petunia seeds that have germinated without harming the other plants.

When should petunia seedlings be pinched?

When the seedlings have three sets of genuine leaves, pinch them for the first time. Under the leaves, new side branches will grow, and the old leaves will drop off. If all threat of frost has gone, pinch them once more when they are approximately 6 inches tall. If so, they will be prepared for transplanting outdoors in a week or two.

What occurs if seedlings are not thinned?

Seedlings that are crowded together will compete with one another for nutrients, water, air, and root space if they are not thinned. You don’t want to deprive your seedlings of those items! Crowding seedlings not only raises worries about competition but also raises the risk of illness. The diminished airflow between the plants is mostly to blame for this. Powdery mildew is a pest that thrives in confined spaces and spreads spores when leaves scrape against one another. All of this is true for both indoor container-grown seedlings (or plants) and outdoor garden-grown plants.

It is ideal to hold off for a few weeks after sprouting, until the plants have grown one or two sets of genuine leaves, but not for too long. After the initial batch of sprouting leaves, the “real leaves” appear. The very first ones are the embryonic leaves, or cotyledons, which are frequently heart-shaped and interchangeable among many plant species. The real leaves more nearly resemble the smaller versions of the mature plant’s leaves. Once a couple of those sprout, it aids in identifying the seedlings with the best appearance.

When it’s time to thin, you get to decide which seedling is the sturdiest, healthiest, and prettiest to keep around. The chosen keepers will flourish after the thinning! In just a few weeks, seedlings can swiftly grow to be four times the size of the ones that were left unthinned! Leaving them unthinned severely hinders their development. This is something I’ve tried out and personally experienced many times!

This is somewhat up to personal preference, like many gardening-related matters, but I’ll discuss the two techniques we typically employ: pruning and gently separating.

A third choice is to hand remove the undesirable seedling from its container, often with the intention of keeping the seedling plucked to replant. Since it can be a little risky, we don’t employ or encourage this approach. The seedling you are intending to save and leave behind in the container may also suffer harm or be totally pulled up with the pulled seedling, defeating your efforts to save it.

Trimming out the undesirable seedlings is our favorite approach for thinning most types of seedlings. With small, sharp trimming scissors, we just cut the smallest, thinnest, or leggiest ones off at the root line, leaving the chosen one behind. We have many pairs of these trimming scissors since we adore them so much! On this homestead, they are commonly employed for a variety of tasks.

We thin almost all of our vegetable seedlings in this manner, whether they were seeded outdoors or in containers. We just don’t need to save the extra ones, in addition to trying to limit potential damage. What in the world were we going to do with all those extra saved plants, given the restricted room in the raised garden beds and under the lights in the greenhouse? As additional insurance, we already start more than we plan to grow. On top of that, we cannot fit dozens more tomatoes, peppers, or squash.

Advantages of trimming

It prevents unintentionally dispersing the one you’ve decided to keepthe strongest and thickest appearing chick by cutting rather than pulling. There is no need to pot anything up or plant anything out at the same time because we are not aiming to keep the ones we have thinned out by cutting (as you may do if you are separating them, explained below). This makes the trimming-based thinning procedure incredibly rapid and simple! All we have to do is cut, then continue.

Notably, we start the majority of our vegetable seedlings in 6-packs or 4-pots rather than tiny peat pellets or smaller cell packs, which lessens the need to pot them up right away. As a result, trimming is even more enticing to us because there is no need to fuss over the plants when thinning. After being thinned, the plants will all be content in their homes for a long time.

Potential Drawbacks:

Some individuals consider the death or loss of these extra seedlings to be a bad thing, an undervalued opportunity for future plants, or even a waste. However, this is not how we see it! Why is this:


Even though we don’t replant the ones we cut, they don’t “go to waste”! The thinnings are micro-greens that are rich in nutrients. We consume them. at least the majority of them.

Which seedlings can you eat? So many varieties! To give you a few examples, edible microgreens include any young greens like lettuce or kale, other brassicas like broccoli or kohlrabi, or essentially any vegetable that you could otherwise eat the leaf of! A more comprehensive list can be found below.

These are great as a salad or dinner topping! Although they can be cooked, we often use them raw. They also produce a really upscale chicken delight. Microgreens retain their most flavor and freshness when stored in the refrigerator in a sealed container, such as a glass Tupperware or ziplock bag, along with a small amount of water.

Here is a list of edible seedlings, and also those you want to avoid consuming

Separating seedlings with care is another way to thin them. To do this, gently remove the seedlings, roots, and entire chunk of soil from the tiny container. The mass may usually be eased out of the container by gently turning it on its side and pressing up from the bottom as necessary. Keep your hands off the seedlings themselves!

Pull apart the seedlings while gently separating the soil. If the roots are knotted together, take care to avoid aggressively ripping them apart. Then, after they have been hardened off, either immediately re-pot the ones you wish to save or get them planted outside! (Post on hardening off is coming next week.)

For flower beginnings like zinnias and sunflower seeds, I utilize this technique most frequently. In my humble opinion, the garden always has more space for flowers! Zinnias in particular, as they are a favorite of monarchs! I prefer to attempt to save as many of those babies as I can. They can tolerate this therapy because they are often quite tough. Additionally, we often start our flower plants a little early and smaller than our vegetable beginnings. As a result, I won’t need to repot them when I separate them and can simply plant them outside. Fava beans are used in the same way. For a little while longer, the peppers and tomatoes in the greenhouse need to be watched for.

Benefits of Separating:

Pulling apart seedlings has the advantage of exponentially increasing the number of plants you can keep. Additionally, if you have a smaller room, you might be able to start more plants.

For instance, if your grow space and shelf are both tiny, you may load six 6-packs into one tray. 36 plants would come from employing the trimming technique, which reduces them to just one plant per cell. However, if you choose to separate out the several sprouts from each cell, you may end up with more than a hundred plants! That is a lot of value for the money. They do, however, need to go somewhere once you separate them. That brings us to a potential drawback of this approach:

Potential negatives

They must be potted into individual containers when you separate out seedlings but it is not yet time to plant them outdoors (for example, they are still too young and sensitive, you haven’t yet hardened them off, or there is still a risk of frost). What will you do with 100 distinct containers, if we stick with the prior example? Even if you have enough area for everyone in your garden, do you have enough room and light to keep everyone content as they wait to go outside?

The length of time required by this procedure is another disadvantage. It makes the thinning process considerably more labor-intensive if you also need to pot them all up or plant them all out at the same time. This could make you less motivated to complete the chore and cause you to put off thinning, which is bad for the plants! I’ve had this feeling before, and I feel the same way about potting up.

The possibility of causing harm to the plants is the method’s final potential drawback. Many plants may tolerate slight root disturbance as long as you are gentle and separate them at an early stage. Even if handled roughly, they normally won’t perish. I can’t help but wonder, “How would they have fared if I hadn’t torn them apart like that,” though, when I do have to be hard with them. Would they be even bigger and stronger, especially if the plants later on in the garden aren’t doing all that well? Because root disruption might result in a minor shock and developmental setback even if they might not perish.

Some plants have extremely fragile, sensitive root systems that do not want at all to be disturbed.

These are the kinds that shouldn’t be thinned by separation. Either direct sowing—where seeds are planted outside where they will eventually grow—or the pruning method should be used to thin them are both acceptable options.

Plants that dislike being transplanted or are sensitive to root disturbance include:

  • Although early gentle transplanting can be beneficial, direct sowing of beans is favored.
  • preferable nasturtiumsdirect sow
  • only direct-sow carrots currently used
  • only direct sow radishes at this time
  • Squash and zucchini can be started indoors, but they must be placed in a large enough container to prevent root entanglement. Before this happens, they should be transplanted outside or potted up.
  • same notes as squash for beets
  • similar notes to squash for spinach
  • same notes as squash and peas
  • Squash notes with melons

Okay, everyone! That’s the skinny on seedling thinning. That is, my opinions and knowledge of seedling thinning.