Best Slow Release Fertilizer for Gardens and Houseplants

#1 · Best Overall

1. Osmocote Smart-Release Plant Food Plus

• Weight: 2 lb
• Form: Granules

Best for: Mixed indoor and outdoor gardeners.

Why it ranks #1: Feeds plants for up to six months with 11 essential nutrients, and its listed uses cover indoor and outdoor plants, containers, beds, and gardens.

Eleven essential nutrients and feeding for up to six months give Osmocote Smart-Release a practical role across a varied plant collection. Its stated use spans indoor and outdoor settings, from houseplants and containers to raised beds and in-ground gardens, so one granular fertilizer can serve several growing areas.

The resin-coated granules release nutrition over time, while the listed 11 essential nutrients support a broad range of plants. Directions call for mixing the granules into the top three inches of soil, then watering regularly; for roses and other plants, they can instead be worked into soil around the base. That application guidance suits gardeners preparing beds or containers, though it does require mixing rather than simply watering in the product.

Skip it if you want a flower-and-vegetable formula with a two-month interval; Scotts All Purpose Flower & Vegetable Plant Food is the more focused option.

Choose this for a mixed indoor-outdoor collection where fewer feeding rounds and broad plant compatibility matter. Allow time to mix granules into soil, and follow the separate guidance for plants such as roses.

Listed on Amazon as: Osmocote Smart-Release Plant Food Plus Outdoor & Indoor1, 2 lb.

#2 · Longest Feeding

2. Dynamite All Purpose Plant Food

• Weight: 2 lb
• Form: Granules

Best for: Long-interval landscape and houseplant care.

Why it ranks #2: Offers nine months of continuous feeding and lists indoor and outdoor plants, including flowering trees, shrubs, houseplants, ferns, and herbs.

Nine months of continuous feeding makes Dynamite All Purpose Plant Food a long-interval option for gardeners tending indoor and outdoor plants. Its listed uses span flowering trees and shrubs, landscape plantings, foliage, houseplants, ferns, palms, grasses, and herbs, with micronutrients included.

The nine-month feeding claim can reduce how often gardeners need to revisit established plantings, while the all-purpose range covers both landscape uses and houseplants. Essential micronutrients add to the product's stated complete nutrition, and application directions call for sprinkling granules evenly around each plant's base. That placement gives a straightforward routine across varied plants, though the long interval and broad use should be considered against the needs of a specific planting.

Skip it if you want a shorter, defined four-month feeding cycle for flowers and vegetables; Osmocote 14-14-14 Slow Release Plant Food is a closer match.

Choose this for gardeners seeking fewer feeding rounds across landscape plants, houseplants, or mixed foliage. Its nine-month interval is a boundary if you prefer to reassess or reapply fertilizer more frequently.

Listed on Amazon as: BLACK (GOLD) KOW Dynamite 2 lb All Purpose 9 Month Plant Food-(887763)

#3 · Vegetable and Flower Pick

3. Osmocote 14-14-14 Plant Food

• Weight: 2.06 kg
• Form: Granules

Best for: Four-month flower and vegetable growers.

Why it ranks #3: Its 14-14-14 formula feeds for up to four months and is specifically listed for vegetables, flowers, annuals, and perennials.

One application feeding for up to four months makes Osmocote 14-14-14 a low-maintenance choice for flowers and vegetables. Its balanced NPK formula is listed for annuals and perennials as well, giving gardeners a single granular option across several common garden plant types.

The 14-14-14 analysis supplies equal listed proportions of nitrogen, phosphorus, and potassium, while gradual nutrient delivery supports consistent feeding. A single application can last up to four months, reducing the need for frequent reapplication across flower or vegetable plantings. Its stated range includes annuals and perennials, so it can cover mixed seasonal beds. The product is sold as a two-pound pack of two, a quantity suited to gardeners managing more than a small isolated planting.

Skip it if you need continuous feeding for up to nine months; Dynamite 9 Month Plant Food offers a longer stated interval for broad plant use.

This is a fit for flower and vegetable gardeners who want balanced feeding and fewer applications across annuals or perennials. Its four-month interval is a boundary for anyone seeking a longer-lasting treatment.

Listed on Amazon as: Osmocote 4 Month 14-14-14 Slow Release Vegetable & Flower Plant Food Fertilizer, 2 Lbs. – Pack of (2)

#4 · Slow-Release Nitrogen

4. GroMaster 10-10-10 Plant Food

• Weight: 5 lb
• Form: Granules

Best for: Mixed plantings needing longer feeding.

Why it ranks #4: The 5-pound granular formula has 50% slow-release nitrogen, feeds for up to three months, and includes micronutrients for mixed plantings.

Fifty percent slow-release nitrogen and feeding for up to three months distinguish GroMaster Fertilizer's 10-10-10 formula. The equal NPK balance is aimed at all-purpose plant nutrition, while listed micronutrients add trace elements for gardeners tending vegetable gardens and mixed plantings.

The 10-10-10 balance provides equal nitrogen, phosphorus, and potassium, and the product specifies 50% slow-release nitrogen for steadier feeding over as long as three months. That longer stated interval can reduce repeat applications, while the description connects slow-release nitrogen with a reduced risk of fertilizer burn. Added trace elements support its mixed-crop positioning. Its five-pound quantity also suits gardeners maintaining larger or multiple plantings, rather than someone needing only a small amount.

Skip it if you prefer a smaller, one-pound granular package with an eight-week interval; GARDENWISE 10-10-10 Plant Fertilizer is listed in that size.

Choose this for mixed plantings where a balanced formula, trace elements, and a longer stated feeding period are useful. The five-pound package makes more sense for broader use than for a few isolated plants.

Listed on Amazon as: 10-10-10 All Purpose Plant Food, 5 lb, with Slow-Release Nitrogen, for Vegetable Gardens and Mixed Plantings

#5 · Organic Granules

5. Organic Plant Magic Granular Fertilizer

• Weight: 4 lb
• Form: Granules

Best for: Organic-minded home gardeners.

Why it ranks #5: This 4-pound granular option is described for indoor and outdoor plants, vegetables, fruit trees, and shrubs, with monthly application suggested.

Monthly application gives Organic Plant Magic a simple recurring rhythm for gardeners who prefer spreadable slow-release granules. The product is listed for indoor and outdoor flowers, vegetables, fruit trees, shrubs, and houseplants, and its directions allow placement in planting holes, mixed into soil, or top-dressed by hand or spreader.

Several application methods make it adaptable to different planting tasks: granules can go into a planting hole, be mixed with soil, or be spread across the surface. The listed monthly use and instruction to water as normal offer a repeatable routine for beds and containers. The product also identifies itself as non-toxic and safe around children and pets, while its safety directions still call for avoiding contact and washing hands after use.

Skip it if you want a longer stated interval between feeds; Dynamite 9 Month Plant Food provides continuous feeding for nine months.

Consider this for gardeners who value flexible placement methods and a monthly routine across indoor and outdoor plantings. Follow the handling directions, and note that its stated cadence calls for regular monthly attention.

Listed on Amazon as: Organic Plant Magic – Truly OrganicTM Slow Release Granular Fertilizer : Long-Lasting Plant Food Granules – Indoor & Outdoor Flowers, Vegetable Gardens, Fruit Trees, Shrubs, House Plants [One 4 lb Bag]

#6

6. Scotts Continuous Release Plant Food

• Weight: 3 lb
• Form: Granules

Best for: In-ground flower and vegetable growers.

Why it ranks #6: Provides continuous-release nitrogen for up to two months and is listed for flowers, vegetables, trees, shrubs, and in-ground gardens.

Up to two months of continuous-release nitrogen makes Scotts All Purpose Flower & Vegetable Plant Food a straightforward option for garden beds. Its listed plant range includes flowers, vegetables, tomatoes, peppers, trees, and shrubs, letting gardeners feed mixed in-ground plantings with one granular product.

Scotts is applied directly to soil around plants, and the supplied coverage guidance gives a workable scale: one cup covers about 30 square feet, or a half tablespoon per square foot. The two-month feeding period also provides a clear repeat schedule during the growing season, starting in spring. Its in-ground emphasis and flower-and-vegetable focus suit bed maintenance better than a buyer seeking the longest interval for a broad container collection.

Skip it if you want one application to last up to six months across indoor and outdoor plants; Osmocote Smart-Release Plant Food Plus fits that broader use.

Choose this for in-ground beds with flowers, vegetables, or mixed garden plants when a two-month feeding routine is manageable. Its stated use is garden-focused, so consider another formula for longer intervals or broader indoor coverage.

Listed on Amazon as: Scotts All Purpose Flower & Vegetable Continuous Release Plant Food, 3 lbs.

#7

7. GARDENWISE 10-10-10 Fertilizer

• Weight: 16 oz
• Form: Granules

Best for: Balanced-feed garden caretakers.

Why it ranks #7: Its balanced 10-10-10 granular formula feeds for up to eight weeks and is listed for gardens, trees, shrubs, flowers, and potted plants.

An equal 10-10-10 nutrient analysis gives GARDENWISE a straightforward fit for gardeners feeding several kinds of plants with one granular formula. Its slow-release claim extends feeding for up to eight weeks, and the listed uses include gardens, fruit trees, evergreens, shrubs, flowers, pots, and indoor plants.

The balanced nitrogen, phosphorus, and potassium percentages make this an all-purpose choice rather than a bloom-specific formula. Its granules are applied evenly to soil and watered thoroughly, a simple routine for garden beds or potted plants. With up to eight weeks of sustained nutrition, the product can reduce application frequency compared with a fertilizer requiring more frequent feeding, while its listed indoor and outdoor uses support a varied planting mix.

Skip it if you need a longer stated feeding interval; GroMaster Fertilizer 10-10-10 All Purpose Plant Food feeds for up to three months.

Pick this for gardeners seeking an evenly balanced feed across vegetables, shrubs, flowers, and pots, with an eight-week schedule. It is less suited to buyers prioritizing a longer stated interval between applications.

Listed on Amazon as: 10-10-10 Plant Fertilizer Slow Release – 10 10 10 All Purpose Granular Garden Fertilizer for Vegetables, Tomato, Arborvitae, Shrubs, Rose, Flowers, Fruit, Fig Trees (1/2 Quart)

#8

8. RAINFLOW 17-17-17 Fertilizer

• Form: Granules

Best for: Gardeners wanting balanced 17-17-17.

Why it ranks #8: The 17-17-17 granular formula is stated to release nutrients for up to 60 days, though the supplied details give limited application guidance.

A balanced 17-17-17 NPK formula and a stated release period of up to 60 days define RAINFLOW Slow Release Fertilizer. Its granular form is presented for varied gardening and agricultural needs, making it an option for growers who want equal listed proportions of nitrogen, phosphorus, and potassium.

The equal 17-17-17 analysis gives the formula a broad nutritional profile, while the slow-release technology is stated to deliver nutrients for up to 60 days. That interval can reduce how often a gardener needs to reapply fertilizer compared with more frequent feeding routines. The listed granular form supports soil application, but the supplied information does not specify a particular application rate or detailed crop-by-crop directions, so buyers should use only the product's available instructions.

Skip it if you want a stated 10-10-10 analysis and detailed soil-application direction; GARDENWISE 10-10-10 Plant Fertilizer provides both.

This suits growers seeking a balanced 17-17-17 granular feed with a stated two-month release window. Consider the limited supplied application guidance before choosing it if you need a specific rate or crop-by-crop routine.

Listed on Amazon as: RAINFLOW 11.28 OZ Slow Release Fertilizer – 17-17-17 All Purpose for Plants

#9

9. Schultz Slow-Release Bloom Fertilizer

• Weight: 16 oz
• Form: Granules

Best for: Gardeners feeding flowering plants.

Why it ranks #9: The 12-24-12 analysis and bloom-specific name suit flower feeding, but the supplied facts do not state a feeding duration or broader plant range.

A 12-24-12 analysis gives Schultz Bloom Plus a phosphorus-forward profile for gardeners selecting a slow-release fertilizer specifically labeled for blooms. Its granular form is applied to soil around flowers, making it a focused choice for flower beds rather than a broadly described all-purpose formula.

The 12-24-12 ratio distinguishes this product from balanced formulas, giving buyers a clearly stated nutrient profile to consider for flowering plants. The listed directions call for applying the granules to soil around flowers, keeping the workflow centered on the root-zone soil. Its 3.5-pound title quantity may suit flower plantings requiring repeated coverage, though the supplied information does not state a feeding duration, so the schedule should follow the product directions rather than an assumed interval.

Skip it if you need a clearly stated multi-month feeding interval; Osmocote 14-14-14 Slow Release Vegetable & Flower Plant Food feeds for up to four months.

Choose this when a flower-focused product and its 12-24-12 analysis match your feeding plan. It is less suitable if a specified duration between applications is essential to your garden-care schedule.

Listed on Amazon as: Schultz 018065 Spf48270 Slow-Release Bloom Fertilizer 3.5 Lbs, 56 Ounce

#10

10. Schultz Slow-Release ACR Fertilizer

• Weight: 16 oz
• Form: Powder

Best for: Powder-form fertilizer shoppers.

Why it ranks #10: The title identifies it as slow-release fertilizer, but its supplied details do not establish a feeding duration, nutrient analysis, or intended plants.

Powder form is the clearest practical distinction of Schultz SPF48340 Slow-Release ACR Fertilizer in the supplied product details. That format sets it apart from granular options for shoppers who specifically want a powder-form slow-release fertilizer, although the listing provides little additional application or nutrient detail.

The product is identified as a slow-release ACR fertilizer and its item form is listed as powder, giving buyers two concrete points for deciding whether it fits their routine. Its safety directions call for gloves and protective clothing, avoiding contact with skin and eyes, and storage in a cool, dry place. Those handling and storage steps matter when planning where to keep and use it. The supplied details do not establish a nutrient ratio or feeding interval.

Skip it if you want a labeled 12-24-12 bloom formula in granules; Schultz Slow-Release Bloom Fertilizer provides that stated nutrient profile and form.

This may suit shoppers specifically seeking a powder-form slow-release fertilizer who can follow its protective handling and storage guidance. Choose another product if a stated nutrient ratio or feeding interval is central to your plan.

Listed on Amazon as: Schultz SPF48340 Slow-Release ACR Fertilizer, 3.5 Lbs, 56 Ounce