Tea Time! We Serve Our Garden Homemade Liquid Kelp Fertilizer

You might remember a certain trip we took to the beach last spring, when we brought home a wagon brimming with several varieties of kelp.

That afternoon back in June, we combined approximately 10 pounds of rinsed seaweed with water inside a 10-gallon Rubbermaid tote and stirred well. Our goal: to brew a liquid kelp fertilizer tea we could use to feed our plants. We covered the container, and in the days and months that followed, we stirred occasionally (every two weeks or so) — even when the ammonia stench became so hellish we had to move it behind the house.

(Thankfully it wasn’t as bad as what’s happening right now inside this Prince Edward Island community.)

The stench of our brown-green brew is long gone, replaced by a pleasant accord of salty and sweet, kind of like a rosy ocean breeze. A sure sign this emulsion is ready to be used…

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In an attempt to deter the bugs that have been assailing our sage, we mulched some seaweed onto the soil.

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Seaweed is rich in amino acids and trace minerals and low in macronutrients like nitrogen and potassium. This might be all we can state with certainty here; while researching this story we wandered into the weeds of a few hot horticultural debates. For one, there’s a whole maze of arguments for and against fertilizing in the fall: the traditional wisdom of “tender growth spurts will be blitzed by frost” vs. “strengthening the roots of plants in late fall leads to robust springtime growth.” Secondly, you could get tennis-spectator neck from reading conflicting reports about the efficacy of seaweed and compost teas.

The jury is also out on the use of foliar sprays (that is, applied directly to leaves) like the one recommended for fertilizer teas. So we closed our laptops and tried it for ourselves.

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Here’s how we made our liquid kelp fertilizer spray:

1. First we siphoned the liquid kelp concentrate from our 10-gallon tub (in which we brewed ~10 pounds of seaweed with water over 5 months) into repurposed Trader Joe’s mineral water bottles. The bottles allow for easy storage and could also make great holiday gifts for likeminded gardener friends. Maybe we’ll design a custom label!

2. Based on some online guidance, we dialed in (and maxed out) our Gilmour No Pre-Mix sprayer to 8 ounces of fertilizer per gallon of water, a dilution ratio of 1:16.

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Bottling seaweed tea fertilizer concentrate for future use.

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The Gilmour No Pre-Mix sprayer attaches to your garden hose and is great for inline dilution.

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We set our sprayer to 8 ounces tea per gallon (128 ounces) of water, which equates to a 1:16 dilution ratio.

3. We attached the sprayer to our hose. The sprayer injects the set ratio of seaweed fertilizer into the water stream.

4. We sprayed the mixture onto the leaves and at the base of several plants, including our African iris, Summer Sky hyssop, natal lilies, fuchsia and nepenthes. It’s ideal to spray in the morning and evening, foliar feeding advocates say, because that’s when the stomata (the leaves’ “pores”) are most open.

We feel optimistic about this extra step we’re taking to support our plants. This weekend — a rare one free of human-based commitments — it felt so good to reconnect with our garden and listen to what it was trying to tell us. And it breathed “kelp me” right into our ears. —TH


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The African iris gets some sweet seaweed satisfaction.

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TLC is also showered on our fuchsia and inch plant.

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Ryan sprays our angelonia and hibiscus.

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The rehabilitation of our nepenthes continues.

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To come: custom labels! Who will be receiving a bottle of this pure Pacific gold for the holidays…?