Starting seeds in growplugs

2:17 pm in Getting Started, How-Tos, Plants, Starting Seeds by britta

Plants, just like people, do best in life when they get a good start. Growing from seed can be a second level challenge. It’s a good idea to start your windowfarm by transplanting semi-mature plants started in soil pots to get the hang of growing hydroponically. Then, you can take on the next level challenge of growing good seedlings for your system while you have adult plants still occupying your bottles.

For questions about what seeds to grow, go here and see the selection of my personal favorites in the seed store.

1) Pretreat seeds to help germination rates

You can help your little seeds along with a few old farmer’s tricks that help the seedlings break through the seed casing.

For smaller seeds, before planting, soak them for a few minutes in a ten percent solution of hydrogen peroxide. This increased our germination rates by about 70%.

For larger seeds, like squash or nasturtium seeds, put them in a small box with a piece of sandpaper and shake! This roughs up the outside of the larger seeds.

Always plant at least 2-3 times the number of seedlings for the slots you have available in your windowfarm. There will be casualties!

You can plant more than one seed per growplug. but when they mature you will need to thin them down to one or max two plants per plug, depending on the plant type.

2) Plant the seed in the growplug at the depth specified on seed packet

Dip the growplug in water (no nutrients! too strong for seeds!) and then squeeze out so that it is like a moist sponge, but is not soaking.

If the seeds are very small and a shallow planting depth is called for, cut the growplug in half vertically. Growplugs are great except when they hold too much water. Smaller plant root systems should have less growplug.

For bigger seeds, which will usually have bigger roots, use the whole growplug.

3) Place in an enclosed container in a good light conditions

I like to use the clear plastic egg containers to start and then move them to a seed tray with a taller cover.

For at least the first 24-48 hours, place them in a dark space. Once you see germination (seedling popping up), then move them to a spot where they get really good light.  Ideally, use a mini T5 growlight placed as close as possible to the seedlings but not close enough to burn them (follow instructions on package). Keep it on for 18 hours a day (you can use your pump timer for this). They do need some darkness as this is the period when they develop their roots.

You can get even better results if you use a germination warming pad which makes sure the seedlings stay at the ideal temperature. We are looking for an environmentally responsible source for these pads for the windowfarms store.

Do not over water and do not let them dry out. Keep that moist sponge condition. Watch for signs of mould or smells of mildew. As they get bigger, remove the top periodically and put them in a breezy window so they develop stronger stems.

Watch for stretching, stems should not be disproportionately long in comparison to early leaves. If so, seedlings are not getting enough light and they are unlikely to do well as mature plants.

4) Transfer the strongest seedlings to the windowfarm

Once seedlings hit about 3″ or 8 cm tall and their roots have emerged from growplugs, you can transfer them to the windowfarm.

Place the growplug gently against one wall inside the net cup. Fill the rest of the cup with clay pellets. Place the cup in the bottle, making sure the seedling is facing out of the hole. It is very important that the little seedling’s stem and the majority of the growplug is not directly under the drip from the bottle above. This will keep the growplug too moist and the force of drips splashing on the little leaves and stems will be torturous. This is the exciting part of caring for your young plants, positioning them well within your window’s microclimate and your windowfarm’s particular configuration for the best possible growing conditions. Watch the seedlings. Continue to look for any signs of flies, aphids, fungus, mildew, or stretching stems. Catching these conditions early is key. If develop a problem, come back to the site and search for that topic or make a new post with a picture and ask for help.

You can try putting two growplugs in opposite ends of a single bottle if you have cut holes on both sides of your bottle. The community has not yet done enough reporting on this and we have had mixed results.