Using Peat Disks to Start Seeds

In North Central Texas, it is time to start your seeds for the cool spring plants you plant outside at the beginning of February.  These plants include broccoli, cabbage, cauliflower, and other above-ground plants.  You can find information on when to plant in North Central Texas here. If you live somewhere else, contact your Extension agent for that information.

Editor’s Note

I have not had success starting vegetables in peat disks. The bottom is soggy and the top dry which either wilts the plant or rots the roots. Other advanced gardeners have had similar problems. I would not suggest using peat disks.

Seed Starting Tray

You can buy seed starting supplies consisting of a black tray with 72 depressions and a clear cover over the tray.  Many come with a peat disk for each depression.   

Peat Disk

You can see each disk has a slight depression in the center of the tablet.  That is where the seeds will go once the pellets are watered and expand. 

Expanding the Peat

To expand the peat disks, put one peat disk in each depression of the tray. First, be sure the slight indention is up.  Next, fill the tray with about 1 ½ inch of water and wait for the disks to absorb it. 

Put Seeds In

After they have expended, each peat disk is big enough to start your seeds in.  The small indention is deeper now.  You want to put two seeds in each hole and cover them up with peat to the depth on the seed package.  Then put the clear cover on the tray.  The lid keeps the humidity high and the peat moist while the seed germinates.  Be sure to mark what seeds you planted in each pot on graph paper. Otherwise, you may find you have a bunch of plants ready to transplant and you don’t know which is which.

Plants Emerge

When you start seeing tiny plants, remove the transparent cover.  If both of the seeds you put in the hole germinate, wait until each has two true leaves.  Pinch the stem of the weaker of the two at ground level.  You can also use cuticle scissors to cut one down.  Do not pull the weaker ones out.  You will destroy the roots of the more vigorous plant if you do so. 

Keep Moist

Keep the peat pots moist by adding water to the tray.  The peat pots absorb the water from the bottom of the peat pot.  Do not water from the top or you risk harming the fragile plant.  Keep the peat pots moist but not soggy.  If they are too wet, the plants will get fungal diseases like damping off. Once one plant gets that, it will quickly spread to the other plants in the tray. 

Light

Once the seeds germinate, it is important that they have a source of light. You can set them on a windowsill, or you can use a grow light. If you put the plants on the window sill, rotate the container 180 degrees every other day, or the plants will all lean toward the window. A grow light should start about 6 inches above the tray. As the plants grow, raise the light so it is always about 6 inches above the plants.

Hardening off

About a week before you intend to plant your plants outside, start hardening them off. This gets the plants used to being outdoors so they don’t die of shock. The first day, leave them out in the shade and sheltered from the wind for an hour. The second day, leave them outside in the shade for 2-4 hours. On the third day, leave them outside in the shade all night. After this, they stay outside all the time. On the fourth day, leave the plants in the sun for an hour. On the fifth day, leave them in the sun for 2-4 hours. On the sixth day, you can plant them in the ground. Be sure to water them in.

Starting seeds in peat disks is an economical way to have great transplants for your garden. You can grow cultivars that are not usually sold in stores this way.