What Is A Seed Tray?

Starting your own plants from seed will often give you healthier plants at a lower cost.  If you want to start seeds in bulk, you may want to consider a seed tray to help with germination.

So, what is a seed tray?  A seed tray is a container used to sow multiple seeds at once.  After seed germination, seedlings grow in the seedling tray until they are large enough for transplant.  A single seed tray can hold anywhere from 6 seeds to over 1000 seeds!

Of course, when choosing a seed tray, there are lots of options for the material, the type of tray, and the number of cells.

In this article, we’ll talk about seed trays and the options that are available.  We’ll also get into how to use seed trays and how to water the seeds and seedlings.

Let’s get going.

What Is A Seed Tray?

A seed tray is a container that is used to plant multiple seeds at once.  A seed tray is sometimes called a seed starting tray.

 A seed tray allows you to plant many seeds together in one container.  This makes it much easier to water them and transport them.

After the seeds germinate, the seed tray holds seedlings as they grow, until they are ready for transplant outdoors or into larger containers.

There are a few different types of seed trays, including:

Mesh seed tray – a mesh seed tray allows water to drain out easily.  A mesh seed tray is best for holding multiple individual containers (pots).  A drawback is that the holes in a mesh seed tray are too large to hold soil without it falling through or washing away when watered. You can find mesh seed trays from Johnny’s Selected Seeds.

Solid seed tray with drainage holes – a solid seed tray with drainage holes allows for adequate drainage, but allows soil to stay moist enough for seed germination.  A solid seed tray with drainage holes is best for planting multiple seeds together in one place.  A drawback is that the seedlings do not have individual cells, so their roots can get tangled together as they grow. You can find solid seed trays with drainage holes from Johnny’s Selected Seeds.

Solid seed tray without drainage holes (leak proof seed tray) – a solid seed tray without drainage holes does not allow for any drainage.  A solid seed tray without drainage holes is best for holding a cell flat (also called a plug flat).  Since it holds water, it can be used to catch excess water from watering seeds, or it can be used to water from below (more detail on this later). You can find cell seed trays without drainage holes from Johnny’s Selected Seeds.

Another interesting option is this seed flat with 20 rows from Johnny’s Selected Seeds. Instead of separate cells, there are separate rows to keep different plant varieties from getting mixed up.

If you decide to use a cell flat for seed germination, each cell should have its own drainage hole.  The tray below the cell flat should be solid without holes if you want to water the seeds from below.

The main problem of adapting the SRI techniques is high labor requirements for manual and lacking of mechanized system for planting single seedling in the field. The existing seedling preparation methods remain challenging among SRI practitioners due to traumatic condition. This study was intended to create modern techniques for increasing the quality and transplanting potentials to improve seedling preparation and reduce transplanting shock. It involved development of rectangular tray having 924 square growing cavities with sliding base to facilitate seedling transfer. Seed selection was conducted and 100% germination was obtained from the sunken MR219 seeds collected in 80 g/L of NaCl solution. SRI-tray seeding was 100% placed into cavities with SRI-seed picker at 150 g/L of tapioca solution. Two different media (Soil + Burnt husk (1:1) as M1 and Soil + Compost (1:1) as M2) were used to evaluate the growth performances for 10 days. The measured parameters (Seedling Height (SH), Leaf Length (LL), Leaf Number (LN), Root Length (RL) and Loosening Index (LI)) were compared between SRI-tray and conventional ones. The SAS revealed that M2 on SRI-tray had the highest significant values for SH, LL, RL and LI with the mean values of 155.6, 109.3, 89.3 and 75 sec when compared with conventional tray which had 125, 91 and 52 mm with no LI, respectively. The seed rate, nursery area and seedling age to support one hectare of planting area were found as 5.34 kg, 36 m2 and 8-10 days on SRI-tray against 15-50 kg, 250-500 m2 and 12-30 days on conventional practices.

The more pellets that are placed in the mould, the denser and stronger the seedling tray with lids.

In cheaper trays, there tend to be slightly bigger gaps between the expanded pellets, and fine plant roots can enter these, making it difficult to pull out the plants.