The Grow Kit includes a 12- or 24-cell tray, expanding coconut coir pellets for each cell, a wicking capillary mat, a large reservoir to hold water, and a platform on which to place the tray and mat.

If you’re growing seeds indoors, a self-watering seed starting system, like the Seed Starting Grow Kit from Gardener’s Supply, will make life much easier.

While almost all self-watering systems work the same way (see details in the sidebar to the right), some of the details vary. And it’s those details that make for a better (or worse) seed starting experience.

Specifications

• 100% post-industrial or pre-consumer recycled plastic, polypropylene capillary mat, coir grow mix pellets
• 12-cell Seedstarter is 14-3/4″ L x 5-1/2″ W
• 24-cell Seedstarter is 14-3/4″ L x 9-1/4″ W
• Each cell is 2″ square x 2-1/4″ H
• Germination dome is 2-3/4″ H
• Water reservoir holds 5 cups (12-cell kit) or 10 cups (24-cell kit)
• Gardener’s Supply Exclusive

What We Liked

Of all the seed starting systems we tested, the Seed Starting Grow Kit had some of the best features. (Note that this review also applies to the Gardener’s Supply Seedstarting Success Kit which, in addition to two 24-cell seed starting grow kits and 48 grow mix pellets, also includes 48 wooden seedling markers and 1.8 oz. of calcium-fortified Easy Grow Fertilizer.)

Here are some of the things we particularly liked about the Grow Kit.

Easy to Fill Tray Cells

The coconut coir pellets expand very quickly when wetted. One pellet is all you need to fill a cell completely – although note that this doesn’t fill the cell to the top.

Have you ever made a mess, with planting mix all over the counter or floor, when trying to fill all those little cells in a seed starting tray? Well, Gardener’s Supply has made that task a lot easier by using expanding coconut coir pellets instead of germinating mix. Just drop one pellet in each cell and add water. Voila, you’re ready to plant!

Easy to Clean

Believe it or not, the Seed Starting Grow Kit is dishwasher safe. That’s right – just run the tray and reservoir through the dishwasher (add a little bleach to help disinfect it) and it’s ready to be used again. Although we experienced no problems with warping or cracking of reservoir after two runs through the dishwasher, we did find that the tray warped slightly and the platforms bent quite a bit. We recommend that you not use a heated dry cycle – just let the parts air dry.

Great Germination Rates

All of these seedlings were grown in the Grow Kit. The seedling second from the left grew in the coconut coir pellets that come with the kit. The one to its right was grown in expanding pellets from Wonder Soil.

Gardener’s Supply says that this kit “ensures 100% germination.” While that’s a pretty bold claim, it certainly turned out to be true in our tests; all seeds germinated and grew strongly in the Grow Kit when sown in the coconut coir pellets that come with the kit.

However, the expanding pellets didn’t do as well when used in other seed starting kits and other mixes didn’t perform nearly as well in the Grow Kit, other than another brand of expanding pellets (Wonder Soil Seed Starting Pellets). More traditional germination mixes didn’t appear to successfully germinate and grow seedlings in this seed starting kit. We recommend using the Grow Kit in combination with the included coconut coir pellets.

If you’re interested in how the Grow Kit coconut coir pellets fared when germinating and growing seeds, you can read our review here.

Less Frequent Watering Needed

With a large water reservoir (the 24-cell kits we tested hold 10 cups of water), you can go longer between waterings. Fill the reservoir to just below the level of the platform and, under most temperature and humidity conditions, you won’t have to fill it again for at least a week.

“Greenhouse Cover” Included

A clear dome covers the entire tray to keep the humidity level constant while seedlings germinate. Be sure to remove it once seedlings have their second set of true leaves; or at least take it off before the seedlings hit the cover.

The greenhouse cover is included with the kit but easy to miss when you first unpack it. Be sure to look inside the reservoir for the cover.

What We Didn’t Like

While there are a lot of positives to the Gardener’s Supply Grow Kit, there are also some features/parts that didn’t live up to expectations.

Fragile Capillary Mat

Even after repeated washing, the capillary mat was heavily stained. When it dried, it was too stiff to reuse.

Despite gentle hand washing, this capillary mat fell apart and couldn’t be reused.

In theory, the capillary mat can be hand washed and re-used “over and over”.

When we removed the seedling trays, we found that the mats were slimy to the touch (and had several patches of green slime on the surface) and smelled like a swamp.

In trying to remove the slime by hand washing in a sink filled with warm water and dish soap, we were surprised to find that the capillary mat fell apart. It didn’t tear; rather, it separated into several pieces and the fabric on the black side of the mat wore off. We were very gentle with the second mat and it stayed in one piece. However, it wasn’t particularly clean and we chose to throw it away, rather than re-using it.

If you want to re-use the capillary mat, we recommend a very, very gentle wash and no wringing – just hang it up to dry.

Support Platform Breaks

The support platform breaks easily into four sections – whether you intend to break it or not. One of ours broke in half while lifting the platform and capillary mat out of the reservoir. It’s not clear why you’d want to break it apart…

The platform has 12 or 24 “feet” on the bottom (the number depends on the number of cells in the seed starting tray). The idea is to flip the platform over and lower the tray onto it so that the feet poke through the center hole in the bottom of each cell to push the soil and seedling out of the tray (so there’s no need to dig around or pull the seedling out by its stem). However, because the “feet” are narrow and tapered, many of them simply poked into the soil, rather than pushing it out of the cell.

Tricky to Fill Reservoir

There’s no opening through which to pour water into the reservoir, and no water level indicator to tell you when water is getting low (or when the reservoir is full – you won’t want to over-fill it). So, to fill the reservoir, you need to lift up the tray, mat, and platform and then pour in the water. If you only have one tray and it’s easily accessible, this would be fine. But if you’re dealing with a lot of trays, especially when growing on stands or under lights, it can get tricky. We probably poured as much water on the floor as we did into the reservoir.

Recommendation

There’s a lot to like about this self-watering seed starting kit – the tray and reservoir clean easily, the cells can be filled simply by placing an expanding pellet in each one and then watering, and germination rates are high when the kit is used with the pellets. Don’t wash the platform in the dishwasher and plan on buying new capillary mats each season. We also don’t recommend using any other type of seed germinating mix with this kit.

For home gardeners looking for a simple and reliable way to grow plants from seed, the Seed Starting Grow Kit from Gardener’s Supply would be a good choice.

Where to Buy

The Seed Starting Grow Kit is available exclusively from Gardener’s Supply. It’s currently priced at $9.95 for the 12-cell kit, $16.95 for the 24-cell kit, and $39.95 for the complete Seed Starting Success Kit. The kit is new in 2014 so is not yet available on Amazon.

Related Reviews and Resources

• Five Keys to Successful Seed Starting
• Best Seed Starting Mixes – Choose the right germination mix for your seeds
• Growing Seedlings Indoors Under Grow Lights – Everything you need to know to do it right
• Where to Buy Seeds – Online sources for high-quality seeds

Which seed starting kits have you used? What worked best for you? Let us know in the comments below!