I’m concerned about leaving fertilizer lying around – I’ve seen it get wet and kind of sticky before – isn’t that bad for it? Why does it get wet anyway?

Fertilizers have a tendency to get wet because many of the compounds included have water in the chemical formula. Getting wet does not affect the viability or usability of the fertilizer, but you can avoid it by adding some Perlite or Vermiculite, which will absorb 10-20 times their weight in water. Here are the chemical formulas for some of the compounds commonly used for Mittleider natural mineral nutrients which have water in them:Calcium Sulfate (Gypsum) CaSO4 – 2(H2O)Copper Sulfate CuSO4 – 5(H2O)Magnesium Sulfate (Epsom Salt) MgSO4 – 7(H2O)Manganese Sulfate MnSO4 – H2OMolybdenum – Sodium Molybdate Na2MoO4 – 2(H2O)Zinc Sulfate ZnSO4 – 7(H2O)As you can see from the above list, half the nutrients used by plants have water as a part of their compounds, and when they are all mixed together their “melting point” is lowered to the point that they sometimes become wet. If you are mixing large amounts – more than will be used in 3-4 weeks, just add about 2% Perlite by weight, and that will absorb any water.