Best Seed Starting Tray (for Germination Success) | Your Indoor Herbs and Garden (2024)

Making seeds germinate is one of the most rewarding parts of growing herbs and plants. However, it is also one of the most challenging. Indeed, seeds require temperature and moisture levels to be within a specific range for successful germination rate (this is the number of seeds that develop out of the total that has been planted).

Of course, with some DIY, you can manage to germinate seeds yourself. However, it might be tedious, you might lose lots of seeds, or take way longer than it should be. That’s where seed starting tray (or even better, seed starting kit) comes in hand.

Seed starting tray and kit (more on the difference later) are designed to provide moisture and stable temperature to drastically increase the chances of the seeds sprout and dramatically shorten their germination time.

There are countless seed germination kits in the market. However, to make your life easier here the two best to go with: the best quality and the cheapest (but still ok) to go for

What Comes With Them?

The best pick is way more than a simple seed starting tray. It comes with:

• 2 large flat trays: these are important in case your seeds come in a pellet (the size of it does not matter). The trays also have holes that suit both 30mm pellets for even more stability when placed. Each tray is 21 inches long and 11 inches high.
  
• 2 plastic domes: these domes are equipped with 4 vents for more uniform control of the internal humidity level. The dome is 7 inches high.
  
• 12 cells trays (each of 12 cells): These 144 cells will give more than enough space to place all the seeds you might want to grow at once. Each cell is 1.8 inches large and 2 inches deep.

The cheapest option, due to its simplicity, makes germination slightly harder, especially for beginners. Its strong point is on the number of cells total available, a whopping 720. More precisely, it comes as 10 trays of 72 cells each. Each tray is 21 inches long and 11 inches large.

Compared to the top pick, the cells in the cheapest option are slightly smaller (1.5 large and 1.8 inches deep). These types of the tray are more suitable for very large applications where thousands of seeds grow in a greenhouse. These can also justify the lack of dome. However, if you are experienced with seeds and can maintain a good temperature and humidity level even without a dome, this is a good choice.

Why Using a Seed Starting Tray? Do You Need One?

As mentioned in detail in the seed germination guide, seeds are eager for relatively high temperature (warm) and high humidity levels. However, at the same time, too high temperature will kill them. Being waterlogged will promote the growth of harmful bacteria or fungi. These will feed on the seed or on the sprouting.

Moreover, without a seed starting tray, you might need to water the seeds more frequently (as the moisture will not be trapped). This not only might cause the seeds to grow more during its development but also cause watering problems (if you are not used to water seeds, chances are that you are going to overwater them).

As this was not enough, planting multiple (more than 3 seeds) in a single small container (As the seeds are very small, especially or herbs) is another thing to avoid. They can easily get entangled as their root system, like thin hairs, will start spreading as much as they can into the soil, which is bad. When you decide to move them to a new planter, there are high chances that you will end up breaking their roots.

You might decide to use several planters. Correct, but in general, you want to grow dozens of seeds at the same time. This is because the seed’s germination rate (even in the best conditions possible) is not 100%. Hence, you will always lose some seeds on the way. However, having dozens of planters just for seeds will use lots of surace area (you should start seeds indoors) and require lots of soil. This is not necessary.

That’s why the seed starter trays are great. They have been designed to address all of these problems at once:

1. They keep the temperature high
2. They keep moisture level high
3. They avoid water logging through proper drainage
4. They avoid seed entanglement
5. They limit the amount of soil needed
6. They are durable and reusable year after year (if of good quality)
7. They make watering hassle-free (water once)

Do you need a seed starter tray?

To really anyone growing plants from seeds, having a tray is a well done micro investment that will save time and money (in wasted seeds) and frustration. This is especially true if you are starting out. Do you want to get discouraged just because the growing medium was too dry or because the room where you placed them was too cold?

How (and Why) Do They Work?

Size and Covering are the real 2 secrets that make seed starting tray so well designed for seed starting.

Size: Just Right

Seed starting tray does their magic first because of their special dimension. They are arranged in tiny cells that allow you to limit the amount of growing medium per seed massively without preventing them from growing.

Look at the cells of the top quality seed starting tray on Amazon. You can notice that the individual cells are deeper than larger. They are rectangular, around 1.5 inches large but 2 inches deep. Indeed, a seedling, differently from a grown plant, does commonly grow more in-depth than horizontally (at least in the sprouting stage).

As you can see from the previously mentioned seed starting tray, the cells are many but “packed” in a small area. This means that they will look neat, tidy whenever you place them and use way less space than any other round-shaped planter you might use.

Moreover, as you can notice in any good quality seed starting tray, they must have drainage holes at the bottom of each cell tray. Indeed, given the low amount of growing medium, it would be almost impossible to not waterlogged the cell without drainage. Moreover, it is important for the aeration of the cell itself.

Dome: What Truly Makes a Difference

A dome is an essential part of a seed start tray. Why? Because it allows solving temperature and moisture problems at once! This is because it leverages a well-known natural phenomenon called the greenhouse effect.

The dome is built out of transparent plastic. It lets the energy from the light reach the soil and the air inside the dome. These, over time, will warm up. Moreover, as the dome is in plastic (a thermal insulator), keep both the air and soil warm over time. This is a paradise for seeds.

Moreover, the humidity level can stay hight as the air is trapped within the dome. However, here is where a good quality seed starting tray comes out. Have a look at the dome of the top pick. You can notice vents. These are great to keep moisture under control, especially if you left the seed starting to try close to a very sunny window, and the dome humidity raised too much.

There is also an extra advantage, especially for a pet owner. Your cat will not feed/play around with the young sprouts as protected by the dome!

Remember

The dome is of massive help in growing seeds, especially if you live in a particularly cold area or, in your house, the temperature varies significantly during the day. It also helps in reducing the number of times you need to water the seeds (as the moisture is trapped).

However, you can grow even without a dome, as in the case of our second pick. It will be more challenging, but if you live in a warm area, or your house has a stable temperature level over the day, you can give it a try. It will allow you to save a few dollars (despite I would not recommend it if you are starting out).

What Makes a Starting Tray Great?

It might look like a simple device to you. Just a plastic tray with a plastic cover on top, right? Even simple things, if done badly, make you regret the few dollars you saved at the beginning. Everything from design to material does really make a difference! The devil is on the details.

Material

Good-quality material trays will last multiple seasons without any crack! This alone will save you money (two low-quality trays are more expensive than a single good-quality one).

Indeed, many of the gardeners I talk to blame their trays for getting damaged (cracked) too often by simple handling. This is because the plastic is extremely thin and brittle. This is often a problem of the bottom part of the cells that can break by a simple, gentle press.

The top pick can easily last multiple seasons. However, remember to store it in the garage, or any other cold/dark place. Indeed, under prolonged periods of time, the plastic can become brittle if exposed to sun or heat.

Material problems of poor quality tray might affect the dome. Small temperature variations (normal in growing seeds) might bend the dome that will not be able to fit on top of the trays.

Extra Features and Versatile

This is something that makes a seed starter tray quite handy. Indeed, it is not uncommon to grow seeds from jiffy pellets. However, most of the low price seed starter kits do not allow that (including the second pick). The cell would not fit a pellet that gets multiple times its size once watered. Moreover, the tray also has some holes that allow fitting, without wobbling, 30mm jiffy pellets to make their transportation way easier.

However, this is not the case of our top pick. Indeed, with the price, it comes also with 2 flat trays (that still fit perfectly with the dome). Those are ideal for placing jiffy pellets on top. Remember, those flat trays do not have drainage holes (as this would be a problem as your tray would leak everywhere if not).

As this was not enough, the top pick also comes with a 12 smaller group of cells. This allows you to place a combination of cells and jiffy pellets on top of a tray depending on your seeds’ needs. Then, you can place a dome on top of the tray, and all is ready to go.

Despite our second choice, it is a good material and has a massive number of cells; it is just that cells. Hence, you cannot place jiffy pellets on it, and it does not come with a dome.

Accessories?

In general, to make seeds germinate, a good quality seed tray is enough. However, if you want to make the best of your seeds, a mat and a grow light are definitely good companions.

Seed Mat: A Warm Seed Ready to Grow

Growing seeds requires adequate temperature. If your house is pretty cold, hence you should consider a mat. Why? This will dramatically reduce germination time and germination rate.

This is simply a thin layer of plastic material with a small resistor inside (an electric component that heats up). This is placed at the bottom of the tray (cells are on top of the tray, to avoid water to leak out).

Is this a luxury item? No, it is always quite cheap and durable if you choose a good one. I would go for a Vivosun quite good quality/price compromise (you can check its current price here on Amazon). It provides uniform heat, and more importantly, is waterproof (important in gardening, especially when indoor).

The 10×20 inches model fits my top pick seed starting tray perfectly.

Just remember to remove the seeds from the mat after 1-2 days the stem gets out from the soil.

Grow Light: To Boost Early Growth

Seeds sprout underground. The majority of them do not need light at all. Hence, why grow light in the first place?

A grow light allows, after the first pair of leaves has grown, to let the seedling grow faster and stronger if you still want to leave the seed in the tray. Indeed, a more vigorous plant is a guarantee of a stronger root system and, as a consequence, of an easier transplant (when moved to an individual planter).

There are countless options really, however, if just for seedling growth, I would go for something easy, as a flexible-neck and a grow light as the Low range relassy (around a dozen dollars, here on Amazon its current price). This can also be used as a desk lamp (once you are done with seedling) by replacing the LED grow lamp with a normal one if you wish, an extra perk for such an inexpensive item.

Seed Starter Mix

In my detailed guide for seed germination, you know that you can also grow seeds with normal potting soil. However, seed starter mixes definitely have the edge. Here, an extremely good one. The extra special is the presence of a fungus called mycorrhizae. This has the special power to bind with the young seedlings becoming essentially extra roots. This boosts plant development in many cases.

Further Questions

Do seed trays need holes? Seed tray needs drainage holes to avoid waterlogging, one of the main causes of seedling, not sprouting.

Do seeds require light to germinate? No, seeds, in general, do not require light to germinate (as most of them develop underground). The light is required by the seedlings (the very young plant that developed the first set of leaves) to continue growing after the nutrients content of the seeds has been exhausted.

How long do seeds can stay in a tray? Seeds are recommended to stay 1, maximum to a week after germination. This depends on the growing medium in which they are in and light conditions. The lower the light (indoor without artificial lighting) and poorer in nutrients is the growing medium (like a kitchen towel, or perlite and vermiculite) the least time the seedling can last in the germination tray.

The Takeaways

1. Seed starting tray makes a significant difference in the time and germination rate, especially if equipped with dome;
   
2. My personal choice for best seed tray (available on Amazon) has the advantage of having cells, flat surface,, holes for jiffy pellets, domes. It gives you the possibility to grow hundreds of seeds!
   
3. The cheapest option comes without a dome, it can work, but it requires a more stable indoor temperature and a bit more patience for germination;
   
4. Heat map, grow light, and seed starting mix are great “extra” that, despite not being necessary for success, increase significantly the odds of having more seeds sprouting in less time. If I have to choose only one of the three, I will go for the seed starting mix.

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