Though you can purchase a Master Gardener Deluxe Kit from AeroGrow that will allow you to use your own seeds, AeroGardeners often choose to reuse the included seed pods. Here are a few methods of reusing a seed pod.
How many of my seeds do I use per pod?
About 6 seeds per pod for smaller seeds and 3-5 for larger seeds. Although AG recommends that you do not thin herbs, some (like basil) do better if you thin to 1 or 2 seedlings per pod.
Sanitize the used seed pod
Wash them in hot soapy water to sterilize.
Replace the sponge
Can I reuse a sponge?
If the sponge hasn't been used you can remove the seeds and replace them with your own seeds. However, if you've already used the seed pod sponge to grow a plant, you should keep the plastic basket and throw out the sponge.
Unlike the AeroGarden branded ones that are made from peat moss, Urban Leaf offers a more sustainable alternative of exactly the same size that are made from coco coir. They are also better value (available here).
- "Cheaper and better than original - Much cheaper than the companies product. Works the same. Great deal. Like growing my own plants at great price"
- "Perfect! - I like these. I like that they are biodegradable. They are the same size as the regular pods, fit the plastic holders perfectly and also fit in the styrofoam seed starting system. I planted lettuce seeds in one and they came up in a few days. A perfect fit for me!"
Park Seed Refills
Park Seeds Peat Bio Sponges #6565
- "I buy the Park seed plugs in the bag of 120. (Usually buy those, two at a time, so I don't have to reorder that often!) I use them not only for the 3 & 6 pod models, but also the 7 pod models. All you have to do is snip a little off the bottom of the pod before putting it in the cage. Works perfectly fine."
- "If anything is my favorite product, i would say its these. I grow everything in those pods. If your thinking of planting your own seeds, i highly recommend them. You can plant your own seeds and really save a ton of money. Seeds are cheap, just remember to order them according to their maximum height."
- "I have used the Park Seed Bio Pods for a long time. They hold together nicely." 
AeroGarden Refill Seed Kit
Hydroponic Home Garden reviewed the Do-It-Yourself AeroGarden Refill Kit. You can reuse the plastic parts from your existing seed kit to grow anything you want in your AeroGarden.
- Contains 21 replacement grow sponges
- Includes a full year of UltraGrow Liquid AeroGarden Nutrients
- Allows you to reuse your existing AeroGarden Seed Kit parts
Rockwool Growing Cubes
Rockwool can be used in place of the growing sponges.
Things you'll need
- A tray of Rockwool cubes, get a tray of small 1” cubes (starter cubes)
- pH Testing Kit
- Lemon Juice (bottled is cheaper)
Where to buy
You can get rockwool at lawn and garden shops, nurseries, etc. 100 cubes for about 10$.
Not all members have had success using Rockwool cubes in their AGs.
- "I used Grodan Rockwool this summer to start seedlings in a tray for planting outdoors. That part went really well. But I had already decided that I would not be using Rockwool in my AG when I saw the sediment left behind after the Rockwool had been soaked for 24 hours to reduce the pH. Rockwool flakes and particles come off the cubes. I checked with other members and they reported the same. I would not want this sediment running through my AGs. During the same period a couple of members were trying out Rockwool in their AGs and the grows were a failure because the Rockwool remained too wet." 
- The first step is to pH balance the Rockwool cubes. The pH scale runs from 0 to 14 with 7 being neutral. Any reading above 7 is alkaline, any reading below is acidic - tap water tends to be alkaline and reads around 7 or above. Plants prefer a slightly acidic solution to grow well, the ideal range is between 5.5 and 6.5
- Fill a 1 litre container with tap water, take a small sample of the water using your pH testing kit and add the stated amount of drops to the sample (2-3 drops). Shake the sample tube and compare the colour to the pH chart – it will normally be green, pH 7 to 8. Add a few drops of lemon juice to the 1 litre water container – lemon juice, being acidic, will lower the pH down to make the water slightly acidic; we need to get the pH down to 5.5
- Repeat this procedure of sample taking, adding lemon juice and testing until you arrive at a pH of 5.5 to 6 – once you have done it a few times it will be much easier and you will know how much to add. Important: do not let the water dip below 5 as, when we add the Rockwool to soak, it will damage the fibres – if the water dips below, just add more water to raise the level back up again.
- Once the water is at 5.5 to 6, put the Rockwool cubes in the water and soak for at least 1 hour. This stabilises the Rockwool, we need to do this as Rockwool has too high a pH - usually 7.8 We don’t want to plant our seeds directly into this as it’s outside the ideal growing zone (pH 5.5 to 6.5).
- When the time is up take the Rockwool, squeeze a little water out of it, and put it in the AeroGarden plastic growing container to check for size. I found that I needed to cut the bottom quarter off the Rockwool cube so it fits better. Always do this when the Rockwool is wet, don’t do it when dry as the fibres are not healthy for you!
- Choose your seeds and insert the seeds into the small hole in the top of each cube. If there is not a pre-made hole then make a small hole a quarter inch / 0.75cm deep. Cover the hole with a bit of Rockwool so the seed has a dark place to sprout from. If it’s too awkward to get the seeds into the hole when in the container, then plant them with the Rockwool removed to make it easier.
- Place the container in your AeroGarden and you’re all done.