Organic vs Synthetic Fertilizer for Cannabis

Every grower has to decide how to feed their plants, and the first big choice is organic or synthetic fertilizer. Both work, and both have trade offs. Here is how each one feeds cannabis and how to pick the right one for your grow.

Organic fertilizer

Organic fertilizer comes from natural materials such as plant matter, animal manure and minerals. Instead of feeding the plant directly, it feeds the soil, and the soil feeds the plant.

The upside

• Richer soil. Organic matter adds a wide range of nutrients, including the big three of nitrogen, phosphorus and potassium. It also improves soil structure so it holds water better.
• Kinder to the environment. It breaks down naturally and adds to soil fertility. It also washes away less easily, so there is less risk of runoff reaching nearby water.

For outdoor beds, our guide to the best fertilizer and compost for growing outdoors covers good options.

The downside

• Slow release. Soil organisms have to break organic matter down first, and that work slows in cold or dry conditions. Plants may grow and flower a little slower as a result.
• Some contamination risk. Now and then organic inputs carry harmful bacteria. Using well composted material and clean gardening habits keeps that risk low.

Synthetic fertilizer

Synthetic fertilizers are made to deliver set amounts of key nutrients such as nitrogen, phosphorus and potassium. They come in precise ratios and are easy to adjust to what your plants need.

The upside

• Fast results. Nutrients are ready for the plant to use right away, which helps when soil is badly short on something.
• Precise control. The label tells you exactly what is inside, so you can give each plant the amounts it needs.
• Easy on the budget. Synthetic feeds are usually affordable.

The downside

• Harder on soil. Frequent use can make soil more acidic and less fertile over time. Synthetic feeds also leach into ground and surface water more easily.
• Easy to overdo. Leaning too hard on them can throw nutrients out of balance, and built up salts can burn roots.

How each one affects growth

Organic fertilizer releases nutrients gradually for strong, steady growth, and it builds a living soil full of helpful microbes. Synthetic fertilizer drives faster growth, but over time it can wear down the soil’s natural nutrients and microbes, so you end up depending on it more.

Which one should you choose?

Indoor growers with a controlled setup often like the quick results of synthetic feeds. Outdoor growers trying to build healthy soil tend to lean organic. Personal values play a part too. Some growers stay organic for environmental reasons, while others want the precision of synthetics.

Kind Seed Co suggests a mix of both for a balanced approach. As a rule of thumb, organic fertilizer suits soil mixes and synthetic nutrients suit hydro. If you want to go fully organic, our guides to making super soil for cannabis plants and growing weed naturally are a good start. If you prefer to mix your own feed, see our DIY marijuana nutrient solution guide.

Look at your space, budget and goals, and watch how your plants respond to find what works best for you.