Fertilizer Basics for Growing in Pots: How to Feed Container Plants Naturally

Learn the basics of fertilizing container plants with organic, budget-friendly options like seaweed, compost, and molasses. Simple tips for growing healthy, productive pots.

When you’re growing plants in containers, you become their entire support system — especially when it comes to nutrients. Unlike garden beds, where roots can stretch and seek out new nutrition, potting soil has limited reserves. Once those nutrients are used up, it’s up to you to keep your potted plants happy and healthy.

Why Container Plants Need Regular Fertilizer

Potting soil often contains some starter nutrients, but they don’t last forever. After a few weeks (or even sooner with heavy watering), plants begin to run low on what they need to grow, bloom, and produce fruit.

Frequent watering — especially during hot summer days — flushes nutrients right out of the pot. That’s why regular fertilizing is essential if you want lush growth or a bountiful harvest.

Choosing the Right Fertilizer for Pots

You don’t need a complicated fertilizer regimen. Organic options are gentle, effective, and easy to use. Here are a few common types:

Organic fertilizer spikes – Convenient and mess-free. Great if you want a set-it-and-forget-it solution.
Granular organic fertilizer – Ideal for slow, long-term feeding.
Liquid fertilizers like fish emulsion – Perfect for a quick boost and easy to mix with your watering routine.

Choose what fits your budget and lifestyle. Most organic fertilizers go a long way and only need to be purchased once a season.

My Container Garden Setup

This year, while we’re living in a rental and settling in our new location, I planted all my herbs and veggies in pots. They’re thriving!

I gave them a good dose of organic fertilizer when I planted, and now I’m keeping them on a regular feeding schedule to help them handle the summer heat and keep producing.

Avoid Salt Buildup in Pots

Be cautious with synthetic or chemical fertilizers. Over time, they can cause salt to build up in the soil, which can burn plant roots and block nutrient absorption.
If you’ve ever noticed a white crust on the soil or pot rim, that’s salt buildup.

Organic fertilizers, on the other hand, are gentler and help maintain long-term soil health without the salt stress.

6 Easy, Organic Fertilizers for Container Plants

These natural fertilizers are easy to find, budget-friendly, and great for your plants. You can rotate them into your watering schedule or use your favorites regularly.

Seaweed Fertilizer

Seaweed contains over 70 trace minerals, natural plant hormones, and enzymes that support plant growth and stress resistance.

How to use: 1 teaspoon powdered seaweed per gallon of water
When to apply: Once a month

Apple Cider Vinegar

Natural apple cider vinegar can improve leaf color, reduce alkaline water issues, and make minerals in the soil more available.

How to use: 2 tablespoons per gallon of water
When to apply: Every time you water

Blackstrap Molasses

Rich in potassium, sulfur, iron, and magnesium, molasses also feeds beneficial microbes in the soil, and may deter ants.

How to use: 1–3 teaspoons per gallon of water
When to apply: Once a month

Compost

Compost is the ultimate slow-release fertilizer. It improves soil texture, retains moisture, and adds beneficial microbes.

How to use: Add 1–2 inches as a top dressing (don’t crowd plant stems)
Bonus tip: Leave space at the top of your container to allow for watering

Worm Castings

Gentle, odor-free, and perfect for both outdoor and indoor pots. Castings feed plants and help maintain moisture.

How to use: Mix into soil or layer on top, then mulch
Bonus tip: Use with compost for a powerhouse combo

Coffee Grounds & Tea Leaves

These kitchen scraps add nitrogen and slightly acidify the soil — great for citrus and tomatoes.

How to use:
- Dry application: Use as a top dressing
- Soak method: Brew in water overnight and use as a soil drench

Final Tips

Your container plants are counting on you, but you don’t need a complicated system. Stick with a few of these organic fertilizers, work them into your watering schedule, and you’ll have thriving, productive plants all season long.