As we near spring the gardeners thoughts turn to growing things and many gardeners decide to start some seeds indoors, to have plants ready to go when the weather conditions are right. If you are going to spend a lot of money on seeds or have precious saved seeds you want to start, you need to know what type of seed starting soil will be best for your investment of time and money.
Before we go further, let’s get some terminology straightened out. Most “soil” you purchase doesn’t contain any real soil- which is earth with a mineral base that is found in nature. Rather it is a mixture of several organic ingredients such as peat, vermiculite, shredded bark and other things. That’s because real soil is heavy, tends to turn into a hard brick when bagged, and each batch would be different, even if the soil was collected from the same area. What is sold in stores for planting and starting seeds is properly called planting medium or planting mix.
The thing that you don’t want to do is use soil or compost from outside or to use soil you have recycled from containers other plants have grown in to start seeds. You don’t want to use real soil sold in garden centers as topsoil either. This is because seedlings are very susceptible to a fungal disease called “dampening off” and outside soil or soil that plants have grown in is likely to carry the fungal spores and infect your new seedlings. It can also carry other diseases and insects that can harm your seedlings.
Planting mediums vary from company to company and different formulas are available for different types of planting activities and different plants. Some planting mixes contain a slow release fertilizer and some contain special water holding granules. A general purpose planting mix could be used for seed starting but it is much better to choose a special mix termed seed starting mix. These mixes are finer in texture and some have been sterilized. The label should plainly state – “seed starting mix”. If you have tiny seed, hard to germinate, rare, or seeds with sentimental value always use a seed starting mix.
If you have larger, relatively inexpensive seeds you could choose a general purpose planting mix. If you are a strict organic gardener you may want to check the label for things like inorganic fertilizers or moisture granules. There are organic mixes available and some even have organic fertilizers added.
Choose a brand name or a house brand made by a well-known company. ( Check house brand labels to see who makes them.) Miracle Gro, Shultz, and Hyponex, and are some big name brands. These companies are more likely to have quality control on their products and they stand behind them should some unlikely contamination or other problem occur. Start with a small bag of the mix if possible, to see if you like it. Different gardeners often prefer different brands of planting/seed starting mix.
Some gardeners prefer not to use mixes that have fertilizers and add their own fertilizer as the seedlings grow. Just remember that if you do choose a mix that doesn’t have fertilizer that the normal minerals found in outside soil that plants need for growth won’t be there. Seedlings can start growing quite well without added fertilizer but as they get their second and third set of leaves they really need some fertilizer added to the mix, if it doesn’t contain fertilizer. If the mix does have fertilizer don’t add more. The mixes use a slow release type of fertilizer that is good for at least 3 months.
Using the seed starting mix
Keep your seed starting mix closed until ready to use, in a warm location. If the mix is cold let it warm to 60-70 degrees before you use it. Make sure your planting containers are new or scrupulously cleaned before use. For very expensive or rare seeds you may want to start with sterilized containers. Always wet the seed planting mix before you put it in the containers. Use warm water if you can as it absorbs better. You’ll probably want a large bucket or bowl for mixing the soil and water.
If you fill the containers with dry mix and try to add water the seed starting mix will float, areas of the mix may remain dry, and it’s just a general mess. If you can, use warm rain water or distilled water rather than softened and treated water, which can contain minerals, salts, or chemicals that harm plants. When properly mixed your seed starting mix should be very moist, without dry pockets but water should not drip when you pick up a handful. If you get the soil too moist put in containers with drainage holes and let it drain before planting the seeds. Pack the soil into the containers with your fingers or with a small block of wood.
Check your seed packages or a good reference for the depth to plant seeds and how to space them. Some growers prefer to cover fine seed with a sprinkle of clean sand instead of planting mix. Make sure to label seeds, so you know what you started. For more seed starting tips see this article. http://www.examiner.com/article/tips-for-starting-seeds-indoors
If for some reason you must use soil or compost from outside or that has been previously used you should sterilize it. Get it moist and spread it an inch or less thick on cookie sheets. Bake at 160-200 degrees F. for 30 minutes. The smell will not be appetizing. Let it cool before using.
After you have transplanted seedlings into the garden you can re-use any planting mixture left in outside containers of annuals or put it on your compost pile. It can also be worked into garden soil.
Here are some additional articles you may want to read.
http://www.examiner.com/article/get-early-color-with-cold-weather-annuals
http://www.examiner.com/article/forcing-branches-into-early-bloom-indoors
To contact the author or to receive her free weekly garden email newsletter, write her at kimwillis151@gmail.com
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