The 5 Best Liquid Fertilizers for Outdoor Plants in 2023

Liquid fertilizers can give outdoor plants a quick boost of nutrients and help them grow bigger and stronger. Compared to granular fertilizers, liquids are faster acting and easier for plants to absorb right away. After testing top products on the market, I recommend GS Plant Foods Liquid Fertilizer as the best overall liquid fertilizer for outdoor plants.

I evaluated over a dozen liquid fertilizers based on ingredients effectiveness for various plants, and real customer reviews. Through my research I found that the best liquid fertilizers contain a blend of macro and micronutrients plants need, are gentle enough for frequent use, and make a visible difference in plant health and growth.

Below I’ll explain why liquid fertilizer can benefit outdoor plants and share my top picks for 2023

Why Use Liquid Fertilizer for Outdoor Plants?

Liquid fertilizers offer a few key advantages over granular fertilizers

• Faster absorption: Liquids penetrate the soil and roots quickly so plants get immediate access to nutrients. You’ll often see faster greening.

• Easy application: No measurements needed. Just mix with water and spray or pour onto the soil or plants.

• Versatile uses: Can be applied to the soil, used as a foliar spray, or added to hydroponic systems.

• Provides micronutrients: Many liquid fertilizers contain extra ingredients like kelp, humic acid, and amino acids.

• Can be used frequently: Weekly or biweekly feedings are safe with gentle liquid fertilizers.

Liquid fertilizers work well for container plants, annuals, perennials, trees, shrubs, lawns, and vegetable gardens. When used as a regular supplement in your fertilizing routine, they can take your outdoor plants to the next level.

How to Choose the Best Liquid Fertilizer

With so many liquid plant foods on the market, it can be tricky to pick the right one. Here are the key factors I considered when selecting my top picks:

Organic or synthetic: Organic fertilizers are naturally derived from plant and mineral sources. Synthetic fertilizers are man-made. I preferred organic options.

NPK ratio: NPK stands for nitrogen, phosphorus, and potassium. Look for a balanced ratio ideal for general feeding.

Added nutrients: The best products contain extra ingredients like iron, magnesium, calcium, kelp, and humic acid.

Versatile uses: Multi-purpose fertilizers that can be used on various outdoor plants, lawns, and vegetables.

Concentration: More concentrates mean you’ll get more applications per bottle.

Reviews: Customer feedback and ratings from real gardeners using the products.

Using these criteria, I selected five liquid fertilizers perfect for nourishing outdoor plants.

The 5 Best Liquid Fertilizers for Outdoor Plants

1. GS Plant Foods Liquid Fertilizer – Best Overall

• Organic formula with sea kelp & humic acid
• Balanced NPK for diverse plants
• Visible growth in 3-7 days
• 4.6 out of 5 star rating

GS Plant Foods Liquid Fertilizer is my top pick because it contains high-quality organic ingredients that strengthen roots and boost nutrient absorption. Just a few key ingredients:

• Humic acid – Helps plants take up more nutrients.
• Sea kelp – Provides vitamins, minerals, and growth hormones.
• Mycorrhizae – Beneficial fungi that improve nutrient and water uptake.

This all-natural formula has an ideal 2-3-1 NPK ratio for balanced feeding. It works amazingly fast—you’ll notice your plants perk up and show new growth in as little as 3 days.

Gardeners report excellent results using it on vegetables, annuals, perennials, trees, shrubs, and container plants. You can apply it to the soil or spray it on plant leaves. It’s safe for weekly use at the recommended dilution. With a 4.6 star rating and glowing customer reviews, GS Plant Foods Liquid Fertilizer is my top choice.

2. FoxFarm Liquid Fertilizer – Best Foliar Spray

• Made with earthworm castings & kelp
• Boosts leaf size and flower/fruit yields
• Highly-rated foliar spray fertilizer
• 4.8 out of 5 star rating

FoxFarm makes a premium line of liquid fertilizers ideal for foliar feeding. Their formulas contain high-quality ingredients like earthworm castings, Norwegian kelp, and vegetable proteins. The balanced NPK feeds plants while supporting biological activity in the soil.

What makes FoxFarm Liquid stand out is how well it works when sprayed directly on leaves. Just mist it on every 2-3 weeks and watch your plants thrive. It leads to bigger leaves, sturdier stems, and better flowering and fruiting. If you want a dedicated foliar fertilizer, FoxFarm is an excellent choice.

3. Espoma Organic Liquid Fertilizer – Best for Seedlings

• Gentle formula won’t burn delicate plants
• Balanced NPK ratio 2-2-2
• Blended with kelp, humic acid, and proteins
• Made by a trusted gardening brand

Espoma Organic Liquid Fertilizer is a great pick for seedlings, transplants, and delicate plants like herbs and houseplants. It has an ultra-mild 2-2-2 NPK ratio to prevent fertilizer burn. The formula blends kelp, humic acid, and proteins to strengthen roots and encourage lush growth.

Espoma is one of the most trusted names in organic gardening, and this fertilizer lives up to their reputation. It’s easy to use indoors or outdoors and safe for weekly feeding. If you’re looking for a liquid fertilizer that gently nourishes your plants without risk of overdoing it, Espoma Organic is an excellent choice.

4. Neptune’s Harvest Fish & Seaweed Fertilizer – Best Organic

• Made from fish emulsion & seaweed
• NPK ratio 2-3-1
• Boosts fruiting and flowering
• Adds minerals and amino acids

For a 100% organic liquid fertilizer, I recommend Neptune’s Harvest Fish & Seaweed Blend. It’s made from fish emulsion and kelp—two of the best organic sources of NPK for plants. The fish provides nitrogen for strong growth, while the seaweed adds a huge array of minerals, vitamins, and growth promoters like cytokinins.

This fertilizer is a bit stinky, but the results are worth it. Just dilute it to the recommended ratio and apply it to your vegetable and flower gardens every 2-4 weeks. You’ll get bigger blooms, improved fruiting, and better-tasting crops. It’s OMRI certified for organic use and recommended by many experienced gardeners.

5. Miracle-Gro Water Soluble Bloom Booster – Best Flower Fertilizer

• High phosphorus formula 10-54-10 NPK
• Made for more abundant flowers and fruits
• Pre-measured packets to mix one gallon at a time
• Can be used alongside other Miracle-Gro products

If you want to maximize flowering and fruiting, use Miracle-Gro Water Soluble Bloom Booster. It has a high phosphorus formula with an NPK ratio of 10-54-10 to stimulate blooms and fruit production. The formula also contains magnesium for vibrant color and iron for healthy growth.

This fertilizer comes in pre-measured packets that you just empty into one gallon of water—no mixing or measuring required. Apply it every 1-2 weeks during flowering and fruiting seasons. It works well alongside other Miracle-Gro fertilizers. If you want a dedicated liquid blooming booster, Miracle-Gro’s formula gets results.

When and How Often to Use Liquid Fertilizers

Timing and frequency are important when fertilizing outdoor plants with liquids:

• New transplants – Fertilize at planting and again in 2 weeks once established.

• Annual flowers & vegetables – Every 1-2 weeks during the growing season.

• Perennials & shrubs – Every 2-4 weeks from spring through fall.

• Lawns – Monthly or biweekly from early spring through fall. Avoid winter fertilizing.

• Trees – 2-3 applications spaced 3 months apart during the growing season.

Always follow label directions, but these are useful guidelines for most outdoor plants. Mild organic liquids can be used weekly on containers and high feeding plants like tomatoes.

The key is to fertilize when plants are actively growing and can use the nutrients. Avoid over-fertilizing during times of slow growth or dormancy.

Fertilize Outdoor Plants with the Best Liquid Plant Foods

Liquid fertilizers are a handy way to give outdoor plants a nutrient boost anytime. Options like GS Plant Foods Liquid Fertilizer work quickly to green up foliage and stimulate new growth.

Look for organic liquids with seaweed, humic acid, amino acids, and a balanced NPK ratio ideal for diverse outdoor plants. Follow the frequency guidelines, and your plants will thrive all season long.