Yesterday, we made a run up to the Adams Fairacre Farms store near us.  They have a well-stocked garden center, open all year, and we went there to procure seed starting mix.  We also found an amazing selection of seeds, including those of the Hudson Valley Seed Library about which I wrote last year (see January 5, 2013).  Good to know in case we decide to buy more seeds this year.

They had at least three brands of seed starting mix on offer, all different from the brand we used last year.  The ingredient lists looked similar and included a combination (in proportions not disclosed) of peat moss, vermiculite and/or perlite.  Some also contained compost or other fertilizers (most notably, the Miracle-Gro product which boasts both Miracle-Gro Plant Food and MicroMax nutrients).  These are superfluous for seed starting; the seed itself contains everything the plant needs from germination until leaf growth.

After browsing the available mixes and looking over the extensive array of soil components and amendments also for sale, I decided to make my own seed starting mix this year.  I recalled from my previous research that all that is really needed is peat moss, for structure, and vermiculite, for water retention.  I have more than a bale of peat moss left over from last year and picked up a bag of vermiculite to add to it.

Today, I decided to do a bit more research to determine what the best ratio of materials might be.  I didn’t find any definitive answers—as with most topics, there are a lot of opinions out there—but I did perceive two common threads.  First, many gardeners recommend adding perlite to keep the mixture lightweight and to facilitate drainage.  Second, several others suggest including a small amount of lime to balance the low pH (high acidity) of peat moss.

I made another trip to Adams (luckily, it is not far away) to buy the perlite and lime.  A definite advantage of the do-it-yourself approach is that all of the mix components are cheap.  For less than $20, I will have enough mix for this year’s seedlings, including potting up.  The lime will last substantially longer (in fact, I will probably never have to buy it again).

When combining the components, I will initially mix two parts peat moss to one part each of vermiculite and perlite. One recipe called for a quarter teaspoon of lime per gallon of mix, which seems low but is as good a starting point as any.  After that, I will adjust as needed to produce a consistency that seems right.

This is a case where my intuition will have to guide me.