How to Start Your Seeds Indoors.


Hi all, this is the first installment of an interesting, fun, and informational blog from The Online Greenhouse. I am going to try and alternate between beginning and advanced topics. I thought that since this is the start of this series we should start out with a topic on propagation! I want to go over some terminology and definition first so we are all on the same page.


Propagation, also referred to as “prop”, is the process for which growers of all kinds of plants will start or multiply their plants. Some methods of propagation include: starting from seed, starting from cuttings, and something called ‘Tissue Culture’. Some other methods are grafting and division. Some things are very easy to divide. Hostas and Hemerocallus (Day Lilly) are two that pop into my head immediately. You will hear some people in the industry refer to starter plants as ‘plugs’ or ‘liners’. Basically they are baby plants… I also jokingly refer to plants started from seed as ‘seed babies’ but that’s not really a thing. I want to focus on starting seed indoors because it is one of the easiest ways to start your plants. Enough with the technical stuff for right now.

Some Experience

Starting from seed is an extremely economical way to start your garden. The cost per plant if you add up the soil, the pot, and the seed is a lot lower than having to buy plants. One thing to realize is that not all the seeds you start will germinate or emerge from the soil, they won’t all grow into healthy plants that fulfill whatever purpose you had in mind. With that said it’s ok to lose plants when starting from seed or growing anything for that matter. Every wholesale nursery I know of plans for a certain number of plants losses. Here are some helpful tips when starting your plants from seed.

Wood Label with Ruler


Read the packet to find out how deep you should plant the seed. A good rule of thumb is the smaller the seed, the closer to the surface it should be. Poppy seeds are tiny and should not be buried, bean seeds are larger and can be planted deeper. I use a wooden label to help measure seed depth and stay consistent. Make a few marks on a label with the help of a ruler. The size container you use is not as important but should reflect how big you expect the plant to grow before planting it into the garden. I use the Six Cell CowPots or the individual 3” CowPots depending on what I have. I will use the 4”, 5”, 6” pots for tomatoes, peppers, eggplants and perennials because I need to start them early in Connecticut (we have a short season). The nice thing about CowPots is you can just plant the whole pot into the next size or directly into the ground without removing the pot!


Consistent water availability for the plant is really important. Think about how in a good growing area, the ground outside is not sopping wet all the time. If the soil is constantly wet and there is greater chance for disease problems. This is mainly because plant roots need to breathe. You also don’t want your soil to completely dry out either, especially when the seed has just germinated. That new plant’s roots are only going to get water it can reach so make sure the first 1/2 inch of soil doesn’t dry out too much. I use Fort Light potting soil from Vermont Compost when starting seeds. I like the addition of pearlite which helps for aeration and drainage and it offsets my habit of over-watering. Vermont Compost Fort Vee is a heavier mix that retains moisture well and is good for the larger containers because it doesn’t dry out as quickly. Remember that starting your seeds indoors in pots is not like starting them in the garden. They are not insulated by the ground and can dry out much faster.


Fertilization is also something to think about when starting seeds indoors. I usually start fertilizing about 2 weeks after the seed germinates. I like to use the organic, more natural fertilizers. I will start with something with a little less nitrogen in it like Neptune’s Harvest Seaweed. Then transition into using their Fish because it has a higher amount of nitrogen in it. If you don’t like the idea of using Fish or Seaweed Fertilizers in your house or greenhouse, you can substitute them for Heidi’s Plant Pep (has a lot of great micros in it) or Organic Plant Magic which has nitrogen in it and is easy to use.

Good luck, and let me know if you have any question as you start your seed indoors!