Can I create custom soil blends without special ingredients?
Written by
Liu Xiaohui
Reviewed by
Prof. Martin Thorne, Ph.D.Making your own custom soil blends? No need for the fancy stuff. Coarse sand helps with drainage, but crushed gravel can achieve the same effect at a lower cost. Don't have perlite? Go with some rice hulls instead. Milk your morning coffee grounds for the nutrients, too, as they will acidify your soil.
Drainage Solutions
- Coarse construction sand: 30-40% by volume
- Crushed gravel: 1-2 inch layer for raised beds
- Broken terracotta pieces: Recycle old pots
- Avoid fine play sand that causes compaction
pH Adjusters
- Crushed eggshells: Raise pH slowly (1 cup/gallon)
- Used coffee grounds: Lower pH (20% volume maximum)
- Wood ash: Increases alkalinity quickly
- Pine needles: Acidify soil over time
Nutrition Boosters
- Banana peel tea: Soak peels for potassium-rich liquid
- Eggshell powder: Calcium source for tomatoes
- Compost tea: Steep compost in water for 48 hours
- Seaweed rinse: Mineral-rich ocean water substitute
Ingredients to combine for "balanced" blends. A 3:1:1 ratio of soil, sand, and compost is recommended for an all-purpose herb mix. Coffee grounds are only for acid-loving plants such as lemon balm. Gravel beneath the root zones of Mediterranean herbs (and layer) on top of your normal mix for suitable drainage. I've made productive blends using only kitchen scraps and yard waste.
Homemade amendments can be beneficial, but they come with some pitfalls to avoid. Don't apply fresh coffee grounds directly to indoor plants, as they can burn the roots. Keep wood ash to a maximum of 1 cup per 5 gallons of mix, as too much will raise the pH (make it more alkaline) incredibly quickly. Always sterilize eggshells first to avoid the risk of salmonella. Always try small batches first before applying them broadly.
Maximize effectiveness by proper processing: bake eggshells at 250°F for 30 minutes prior to crushing; compost coffee grounds (choose materials with the greatest concentration first) in order to neutralize their acidity; age compost made with manure-like components for 12 months; you thus convert raw materials into safe, potent soil enhancers which compare very favorably with the commercial catchalls.
Read the full article: Best Soil for Herbs: Ultimate Growing Guide
