Seaweed Fertilizer

In spring and summer, apply once weekly at 2-4 tsp per gallon in a watering can, then water as usual, or use the hose-end sprayer on the 1 Tbs setting. In fall and winter, cut back to once every 4 weeks. Because it's a biostimulant rather than a feed, it's gentle and hard to overapply, but weekly use through the growing season is where you'll see the resilience and uptake benefits build up.

At 1 tsp per quart, the 8 oz bottle makes about 48 watering cans of feed. For a typical shelf of 10–15 plants fed every 1–2 weeks in season, that's several months of feeding — and the 32 oz bottle four times that.

Regular fertilizer supplies nitrogen, phosphorus, and potassium that feed the plant's growth. Seaweed fertilizer is a biostimulant — it provides natural growth compounds, hormones, and trace elements from kelp and microalgae that help plants take up nutrients and handle stress, but very little NPK. It has no fertilizer ratio because feeding isn't its job. Use the two together: your fertilizer feeds the plant, and this helps the plant make the most of it.

No — it doesn't supply meaningful nitrogen, phosphorus, or potassium, so it can't replace a fertilizer. A plant given only seaweed would slowly run short on the nutrients it needs to grow. Think of it as a supplement that improves resilience and uptake, used alongside a complete fertilizer. It's one of the most useful add-ons for a feeding program, but it works with a fertilizer, not instead of one.

This is one of its best uses. The natural compounds in kelp support root development and help plants handle the stress of being moved, so many gardeners apply seaweed at transplanting and after. It won't guarantee a plant survives a rough transplant, but it supports recovery alongside good watering and placement. Use it when setting out seedlings, potting up, or moving plants, and continue through the establishment period.

Biostimulant benefits are gradual and show up as steadier, more resilient growth rather than a dramatic green-up — you may notice better recovery from stress and stronger root and overall vigor over a few weeks of regular use. It works best as part of an ongoing program, where the resilience and uptake benefits compound across the season, rather than from a single application.