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Learning to grow seeds with sponges is a hack that all gardeners should take the time to master. Starting seeds in sponges is massively beneficial.

The process is quick, easy, and there is no mess involved whatsoever. Even more, growing seeds with sponges is a great learning experience, whether for children or adults.

So, in this article, we’re going to discuss everything you need to know to start growing seeds with sponges today.

Growing Seeds in Sponges

Starting seeds is one of the most important steps to a successful crop. Regardless if you prefer organic gardening, hydroponics, or another growing method, you need a steady supply of healthy seeds each year.

Starting seeds in sponges allow you to skip the typical techniques like moist paper towels, bowls of water, and soil plugs. Growing seeds in sponges is not only quicker, and less messy, but it also saves you money and gives you more control over the process.

Let’s have a look at the entire process, below!

How to Prepare Sponges for Planting Seeds

Plating seeds in a sponge is relatively easy in comparison to other seed-starting methods.

Here are the steps:

  1. Decide how big and what shape you want your sponges to be and cut them as needed (if you’re using some sort of brandname hydroponic seed starter system this part is crucial as they’ll need to fit properly)
  2. If it doesn’t already have holes in it big enough for seeds you need to create some holes in the sponge by poking it with a sharp knife tip (or using a razor blade to create slits to place the seeds)
  3. Sterilize the sponge by dampening it and throwing it in the microwave for about four to five minutes (or toss it in a pot with boiling water for 60 seconds)
  4. (Optional) Mix a bit of bleach with water and soak the sponge for a few minutes and then remove them and rinse thoroughly (this helps prevent mildew or mold showing up on the sponge later)

How to Plant Seeds in Sponges

After you prepare your sponge for planting:

  1. Soak the sponge with clean water
  2. Place the sponge in a tray (or another seed starting system if you have one)
  3. Depending on what you are planting (small leafy vegetables like lettuce, or larger plants like tomatoes), either stick several seeds in the slits or holes in the sponge or place a single seed in the center
  4. Place the tray in a darkish and warm location
  5. (Optional) Cover the tray with a lid or plastic wrap
  6. Regularly check on your sponge(s) and spritz them with a bit of water (but avoid soaking them other than when first planting)

How to Transplant Seedlings from a Sponge

A seedling with the beginnings of roots developing, held between a finger and thumb. There is a seed casing still on the top of the sprouting seedling. The background is black.

Transplanting plants from sponges is commonly done in one of two ways; gently pulling the entire plant up and away from the sponge until it is free and then planting it, or trimming the sponge down and transplanting the remainder of it along with the plant so as not to disturb the roots.

Seeds grown in sponges are transplantable to any sort of growing medium. If you prefer soil, simply make room for them in a container, or in the garden, water the soil, and plant them as you would any other transplant. Likewise, if you’re a hydroponic grower you can place them into your netted pots with whatever sort of hydroponic growing medium you use.

To transplant your sprouted seedlings, either remove them entirely and place in a pot or outdoor bed when ready or trim the sponge down and plant the roots with the remaining sponge still attached to them. The latter is useful if the roots are too delicate and can’t be easily removed from the sponge. Once they’re big enough, you can use sponge-grown seedlings as you would any seeds you started in soil.

Best Seeds to Start in Sponges

Now that we’ve covered preparing sponges, planting seeds in them, and transplanting once the seeds are grown, let’s take a quick look at some of the best plants to start in sponges:

Best Types of Sponges to Use for Growing

There are several types of sponges that work great for growing seeds. A few of the best sorts of sponges (and alternatives) to use for planting seeds are:

  • Rockwool Cubes
  • Peat Moss
  • Coco Coir
  • Kitchen Sponges
  • Organic Sponges
  • Foam Sponges
  • Hydroponic Sponges

A Final Word About Growing Seeds in Sponges

Growing seeds in sponges is an excellent method to master if you’re an avid gardener (or plan on picking up gardening as a hobby). The technique has a high success rate and works for many types of seeds including vegetables, fruits, herbs, flowers, and houseplants.


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