Spring 2026 · Soil spotlight
Garden math, answered.
5 free, source-cited calculators for growers who want a number, not a newsletter.
In this issue
A field guide to spring soil preparation
pH, drainage, amendments — the three decisions to make before the last frost.
Featured calculators
Practical calculators for common garden jobs
Start with any tool below; each one shows its source basis and assumptions.
Compost Calculator
Calculate finished compost volume and bag count, or screen a pile's browns-and-greens mix.
Garden
Watering Schedule Calculator
Estimate net weekly irrigation in inches and gallons by crop, soil, season, growing method, bed area, and recent rainfall.
Garden
Soil pH Calculator
Check target garden pH, compare crop ranges, and estimate lime or sulfur with a quick chart.
Garden
Seed Spacing Calculator
Plan rows and estimate plant and seed counts with extension-cited plant spacing, row spacing, and seed depth for 20 home-garden crops.
Garden
Fertilizer Calculator
Calculate NPK fertilizer dosage for any crop or garden area.
Garden
From the Almanac
Long-reads to go with the numbers
Each guide pairs with a calculator and cites its University Extension sources.
Almanac · Growing
How to grow tomatoes in a home garden
Planting time, spacing, soil, feeding, watering, disease prevention, and harvest cues — with an extension source behind every number.
Full guide
Almanac · Soil
Understanding soil pH for beginners
A field guide to reading your soil — what pH actually means for root uptake, and how to correct it over a season.
12 min read
Almanac · Composting
The complete home-composting guide
Greens, browns, ratios, and the two-pile rhythm that actually works on a small lot.
14 min read
Almanac · Fertilizer
How to fertilize a vegetable garden
NPK, side-dressing, and the three deficiency signs every small-plot grower should recognize.
11 min read
Extension-sourced formulas
Every calculator cites at least two .edu or .gov references — no Reddit, no Brainly.
Used by home growers
Home gardeners, community plots, and master-gardener programs.
No account required
Calculator inputs stay in your browser. Nothing to register. Embed freely.