My new favorite seed starting supplies - Ask the Food Geek

I finally bought reusable seed starting trays to replace the flimsy black plastic ones that crack apart after a single season. The new seed starting trays are silicon, can be sanitized in the dishwasher, and come with humidity domes and built in mini grow lights.

With competitive price and timely delivery, MARSHINE sincerely hope to be your supplier and partner.

The cost is pretty affordable as well, coming out to about $0.50 cents per plant. I plan to use these for the next 10 years or more, which means they would come out to about $0.05 cents instead!

Jump to:

• My current seed starting setup
• Product details
• Seed starting mixes
• Alternative seed starting options
• Where to buy
• Store your seeds in a binder
• You might also like

My current seed starting setup

I bought these colorful silicon seed starting trays this year - both for fun and function. They sit adorably in the window, making me smile every time I walk by. As a bonus - they are as practical as they are cute.

Update : sadly, the company no longer makes this product. I found something similar on Amazon, so you can try these instead, which look to be very similar (but less colorful).

Why use silicon seed starting trays

Silicon seed starting trays have recently started popping up and are gaining popularity over the standard paper-thin black plastic trays you find at nurseries. Those plastic trays crack after one use and can get a bit toasty on a seedling heat mat.

The silicon trays are flexible, making it easy to push on the bottom to pop the plant out for transplanting. They can also be placed in the dishwasher for easy sanitizing year after year.

Why these trays

I bought the 8-pack of silicon trays that each come with a thick plastic bottom, and a tall 4" humidity dome with mini grow lights built in. It also comes with 80 plant tags and a couple mini plastic tools for punching holes in soil or scooping soil. Each tray has 9 cells for a total of 72 cells.

Product details

I took measurements of the seed starting trays in case you are trying to fit them on a windowsill, a standard tray size, or trying to determine what to use for your seed starting medium.

• Silicon tray is exactly 5" x 5"
• Cell interior is 1.5" x 1.5"
• Silicon tray height: 2.25"
• Plastic tray: 5.75" x 5.75" to edge of lip, and 4.75" x 4.75" across the bottom
• Plastic tray height: 2.75"
• Dome: 4" high
• USB cable to power grow lights: 14" long

The 8-pack of silicon trays comes with 4 USB "double" cables to power the grow lights. Each cable splits into 2 cords and each of those cords is 14" long. I bought a $15 USB power strip from Amazon to plug them in.

Everything you need for seed starting is listed at the bottom of this post, in one place.

Seed starting mixes

In my experience, the most important factor for successful seed starting is finding the right soil or growing medium. This can make germination easy or near impossible, depending on what you choose. The two easiest seed starting options are Horticubes and OrganiPlugs. Seed starting soil mixes are also a good option.

Seeds need to stay moist in order to germinate. It might seem like you can simply pick any soil and keep it watered, but too much water without drying out invites mold. Mold can stunt or kill the seedlings.

Seed starting soil mixes are formulated to hold moisture, often including perlite or peat, which is a good thing! But I've found soil to be too finicky for seed germination for my liking. It seems too easy to underwater, resulting in poor germination, but overwatering often leads to mold growth on the top. I know other people who have had more luck with soil mixes or soil blocking.

This year I'm trying out OrganiPlugs and they've worked out well so far. They are made of peat and coco coir and feel quite spongy. They stay moist and so far I haven't run into mold problems (and don't expect to).

OrganiPlugs are made to fit into standard seed starting trays. They fit almost perfectly in each cell of the silicon trays I bought - they have just a little bit of wiggle room.

I'm also using Horticubes for herbs this year. They don't fit in the silicon trays, instead they are meant to sit in a large tray then get transplanted shortly after germination.

(All of the products are also listed at the bottom of this post in one place).

Alternative seed starting options

I have a couple other options to suggest if for some reason you don't want to share in the joy of these cute, resusable trays!

Upcycle disposable containers

Empty yogurt, fruit cup, or applesauce containers make great seed starting pots - just be sure to drill a few holes in the bottom. Leftover take-out containers work well as a tray to collect the draining water.

When upcycling containers, you'll likely need to use a seed starting soil mix. If you do this, be sure to check the moisture levels several times a day so it doesn't dry out, or stay too wet.

OrganiPlug pre-filled tray

OrganiPlug offers a 50-cell tray pre-filled with their OrganiPlugs. It doesn't get much easier than that. However, the tray will likely only be usable for 1-2 years as the thin plastic will crack as you remove the plants for transplanting.

Oasis Horticubes

I actually use this seed starting method every year, including this year - Horticubes. They are the most reliable and easiest seed germinating medium. I really can't stress how easy these are to use.

These feel like foam but are made from biodegradable materials that will continuously break down over the course of the year. It's sterile medium so it won't transfer pests or diseases.

Horticubes hold water extremely well and don't mold. Seed germination is easy and all but guaranteed. I never run into problems when using Horticubes.

The downside is they are very small and offer no nutrients. That's fine for germination but they will need to be transplanted to larger containers as soon as their first set to true leaves shows up. If you don't transplant, they just stop growing (I know, because I've done it!)

I use these every year for starting herb seeds where I want a bunch of each type of plant. Once they sprout, I transplant them to a larger tray with soil that I continue to water. When they are ready to be transplanted outdoors, I break apart the roots if they've grown together and set them in their sunny spots!

One note worth mentioning is the sheets that arrive are fragile. They can easily break apart if you aren't careful or if shipping was rough.

Get Horticubes on Amazon or Harris Seeds for a similar price.

Other options

There are a few other options to consider - rockwool, foam plugs, and seed starting soil mixes. I don't think these options are as good as the ones listed above, however.

Rockwool is made from molten rock that is spun into threads to create the product. I used rockwool cubes a while back but stopped when I learned it might be harmful to the lungs.

It's too bad because they are a fantastic medium. They are relatively cheap ($0.10 per cube or less), hold water extremely well, and never mold. Seed germination in these is outstanding.

Some people still use them, and I don't feel like I've found enough credible evidence to confidently advise against using these. I personally don't use them because I prefer to err on the side of caution, and I've found other alternatives.

Foam plugs are another option. They actually work quite well - they hold water, don't mold, and are affordable. But I personally don't use them because they don't compost into the soil, leaving little spongy plugs around.

Seed starting soils are formulated specifically for seed starting. They often contain perlite, peat, and coco coir to hold water. As I mentioned earlier though, I always have trouble with either over watering and getting mold problems, or underwatering, resulting in poor germination.

If you've had luck with seed starting soils in the past, then I see no reason you wouldn't continue to have success. It's a good, affordable option!

Where to buy

Amazon is actually a great place for seed starting supplies. I find their prices are often much lower than online seed websites and even hardware stores. The links in this article are affiliate links, which means I get a small commission if you make a purchase (and a big thanks if you do!). In return, I only recommend products that I personally use and feel good recommending.

Everything you need for seed starting with my silicon tray setup:

• OrganiPlug 100 count
• A USB hub for the grow lights

Alternatives

For more information, please visit cheap seed starting trays.

• OrganiPlug pre-filled tray
• Horticubes (larger) - these are the ones I use
• Horticubes (smaller)
• Black plastic 6-cell nursery packs (thin plastic, 1-2 uses)
• Plastic plant labels

Extras:

Seeds need warmth to germinate, so most people set them on a little heat mat. Once they germinate, remove them from the heat mat and leave them at room temperature.

The heat mats get slightly warmer than room temperature, and the inexpensive ones don't have controls other than being plugged in or not. Mine are all like this and were very inexpensive (small ones are around $15). This 10x20" heat mat will fit the 8 silicon trays (they might hang off the edges a little). I don't have this one in particular because I bought mine over 10 years ago. It has good reviews and looks exactly the same as what I use.

Alternatively, set your seeds on top of your fridge to germinate. It's just warm enough to lend a helping hand instead of a heat mat.

Where to buy seeds

I bought seeds from a dozen vendors last year. In part it was to evaluate vendors since so many people ask me for my favorite sources. But part of it was chasing unique varieties that only one or two vendors sold.

I share a dozen of the best places to buy seeds, from incredibly cheap sources for $2 or less, to fully organic but more expensive. I also have a good source that specializes in each specific climate, including the Pacific Northwest, West Coast, Southwest, Southeast, Midwest, and Northeast.

For information on how to start your seeds, Swanson Nursery has a good tutorial.

Store your seeds in a binder

4-pocket binder sheets fit seed packets perfectly. The smallest pack you can buy seems to be 25-30, which gives you 100-120 pockets. When storing them back-to-back (one faces front, one faces back), you get double the storage for 200-240 seed packets. I bought a 50-pack and it was way too many - oops.

I also bought a 1.5" thick binder which was definitely too small. I would definitely recommend a 3" ring binder, especially if you are storing large seeds like beans, peas, and corn.

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A Quick Overview of Seed Starting

Starting seeds for your garden is one of the most exciting things you can do. To see something so small grow into a beautiful and productive part of your garden is magical. But for a lot of new gardeners, it can seem overwhelming to start. How exactly do you do it? How do you know what materials to use? How do you know when your seedlings are ready to be planted outside?

Well, Gardenary is here with plenty of answers and information all about starting seeds! Check out these articles:

• When to start seeds indoors
• What materials you'll need
• How to harden off and transplant your seedlings outdoors

In this post, we're going to take a deeper dive into the different seed starting setups, in particular the trays and kits. There are so many options to pick from, so let’s take a look at what all you can use!

What Should Your Seed Starting Setup Look Like?

When starting seeds indoors, just remember that you are trying to mimic the outdoors as much as possible. You'll want the temperature to be warm and the area to have perhaps a little humidity, if possible. There also needs to be some air flow and light. While some people choose to use natural light, your seedlings are going to grow weak and leggy unless they're in a greenhouse with full overhead sunlight. Being placed on a windowsill is often not enough. Your best bet is to grab a grow light to use in whatever location your seeds will grow.

I have been starting seeds indoors for years now, so I will show you an example of how I started versus how I'm doing it now: In the beginning, I used styrofoam cups placed on a baking tray, with a clip-on grow light, in my office. Super simple and cheap, but effective! I didn’t need to start a ton of seeds because my growing space was little, so this worked well enough.

As my garden expanded, I invested in more materials in order to start more and more seeds. Now I have an extra bedroom closet I use, with a shelving unit, attached grow lights, and seed trays. This setup was more labor intensive and expensive to get going, but I can start a lot more seeds this way, and by now, I know the investment is worth it.

What Materials Can You Use to Start Seeds?

While my personal preference is a seed starting tray, there are other things you can use to get going. Let's look at some of the advantages and disadvantages of different materials.

Seed Starting with Household Items

Many gardeners trying to reuse what is already in their home will start seeds in eggshells, egg cartons, rolled-up newspaper pots, yogurt cups, toilet paper rolls, and more.

Advantages

A lot of these materials are biodegradable, so the whole pot can be planted directly into the soil. That is definitely a benefit, as is the ability to repurpose something that would otherwise be tossed in the trash.

Disadvantages

I have tried a few of these items and either found them to be too small or had them decay and break down before I could plant my seedlings outdoors.

Seed Starting with Peat Pots or Coco Coir Discs

These are pre-made pots, trays, and discs (also called pellets) sold widely online and in stores.

Advantages

They're biodegradable, so again, you can plant the entire pot or disc.

Disadvantages

I've had some get moldy and—like what happened when I tried to use toilet paper rolls—break down too quickly when exposed to water. I am not a fan. Plus, you have to pay for something that's not reusable.

Seed Starting with Plastic Cups, Styrofoam Cups, and Small Reusable Pots

You can poke holes in the bottom of just about any cup and use it to start your seeds. Be sure to place them on a surface or tray that can catch runoff when you water them (like my baking sheet in my original setup).

Advantage

The benefit of these is that they are bigger and thus can grow your seeds all the way to transplantation without needing to pot them up (in other words, you don't have to move them to a larger pot before they go into the garden).

Disadvantage

The negative is that they take up way more space than the cells of a typical seed starting tray.

Seed Starting with Soil Blocking

Another option that is gaining popularity is to use soil blocking. While this option has technically been around for centuries, many home gardeners have never seen it used. 

Advantage

The beauty of this option is that you use the soil as both the growing medium and the container. The soil is packed enough to stay together and allow the seed to grow roots without running out of space. 

Disadvantage

You do need a few particular items to get started.

I know many gardeners who are turning to this method and quite enjoy it. You can see the items you need here and read up on how to's.

My Favorite Seed Starting Trays

My top pick would have to be from Johnny’s Selected Seeds. Everyone knows their seed starting materials are top notch, and I love supporting a company that has such a great reputation and relationship with its employees. Their trays can be a bit on the pricier side, but you know that they will last for years. They have numerous options to choose from, so here are a few you might want to try:

• 72 Cell Plug Flat - This tray can be used for almost anything growing in your garden. These are the ones I currently use (pictured below).
• SureRoots 50 Cell Deep Plug Flat - This tray is great for anything with a longer taproot or something that may be disturbed during transplanting, such as sweet peas or perennial plants.
• 128 Cell Plug Flat - This tray will definitely give you plenty of spots for seeds in the space provided. This tray would work for things like greens and herbs that don’t need a ton of space.
• Pro-Tray 24 Cell Flat - This tray with larger spaces is better for your larger plants like tomatoes, eggplant, melons, pumpkins, and squash.

With any of these trays, make sure you also order trays to catch or hold water underneath if you're growing indoors, as these trays all have holes that allow for drainage or uptake of water.

Plenty of other companies have similar tray setups that are good quality. You can get a kit from Gardeners' Supply that includes a 12- or 24-cell tray and a mat, and Burpee has a similar setup that also includes a dome lid, markers, and grow pellets. Growers Supply carries similar products, but you have to order a certain number of trays, not just one. 

Amazon has a really neat kit that has a 60-cell tray with a mat and dome lid, as well as a grow light—a great setup for beginners! You can also find inexpensive trays and kits at places like Home Depot, as well as your local gardening supply stores.

A Couple of Quick Tips on Using Trays to Start Seeds

Tip #1

You can water at the top or the bottom. Many people get fungal disease, which affects seedling growth, by watering on top of the soil if it is kept too moist. This has never happened to me, but you want to be careful how much water you use. You can avoid this issue by pouring water into the bottom catch tray; the seedlings will absorb it up through the holes in the tray.

Tip #2

When it comes time to remove your seedlings, a butter knife is your best friend. Just insert it gently along the side of the soil and pop your seedling out.

Tip #3

Always be sure to wash and sterilize your tray kits before use for new seeds. The moment after I transplant my seedlings, I wash my trays out and remove any dirt or debris and let them dry out before storage. When it comes time to start new seeds, I soak my trays in a diluted bleach solution to kill off any lingering bacteria that could harm my new seed babies. You can use a 9:1 ratio of water to bleach, or 9 cups of water for every 1 cup of bleach.

Is a seed starting heat mat necessary? 

I personally do not use a heating mat and do just fine; however, I see plenty of gardeners and, for sure, farmers who use them and have excellent and speedier germination. I don’t feel this is necessary to get started if your space is warm, but it can definitely help.

There is also an option to purchase a dome. I have used domes at times and not used them at times, and in my opinion, they aren’t totally necessary if you have a warm space to start your seeds. If your space is a little cooler, like less than 72 degrees, then a dome can provide extra warmth and humidity for your seeds to germinate.

If you want to learn more, please visit our website Leak-Proof Seedling Trays.