Best Slow-Release Fertilizers (2026)

A good slow-release fertilizer is the closest thing gardening has to set-and-forget feeding. You mix a measured amount into the soil at planting, water it in, and the granules feed for two to six months instead of the one to two weeks you get from a liquid feed. For most container gardens, mixed beds and shrub borders, our top pick is Osmocote Smart-Release Plant Food Plus, a resin-coated granule that the listing says feeds for up to six months indoors or out. For vegetable beds, Osmocote’s 14-14-14 Flower & Vegetable formula is the stronger choice. Below are seven picks for different jobs, and how to use them so they actually last as long as the label says.

Part of our Composting & Soil guide →

In this guide

1. 1. Osmocote Smart-Release Plant Food Plus — Best Overall
2. 2. Osmocote Smart-Release Flower & Vegetable — Best for Vegetable Beds
3. 3. Miracle-Gro Shake ‘N Feed All Purpose — Best Easy Shaker for Containers
4. 4. Scotts All Purpose Flower & Vegetable — Best for In-Ground Flower Beds
5. 5. GroMaster 10-10-10 All Purpose — Best Value for Large Gardens
6. 6. The Grow Co Indoor Plant Food — Best Granules for Houseplants
7. 7. RAINFLOW Plant Fertilizer Sticks — Best Spikes for Potted Plants
8. What to Look for in a Slow-Release Fertilizer
9. How to Use Slow-Release Fertilizer
10. Frequently Asked Questions

Disclosure: Urban Lotus Project earns a commission from qualifying Amazon purchases made through links on this page, at no extra cost to you.

How we compared: we compared 13 current Amazon listings for slow- and controlled-release fertilizers on what each listing states about release duration, NPK, coverage and intended plants. We did not test or handle the products, and availability changes.

1. Osmocote Smart-Release Plant Food Plus — Best Overall

Best overall

Why We Like It

• Longest stated feeding window on the shelf
• Resin coating meters out nutrients gradually
• Labeled for indoor and outdoor plants
• No-burn pledge when used as directed

Specification	Details
Release type	Resin-coated granules
Duration	Up to 6 months
Nutrients	11 essential nutrients; NPK not stated in listing
Coverage	Up to 300 sq ft per 8 lb
Use	Containers, raised beds, in-ground, houseplants
Sizes on shelf	1 lb, 2 lb and 8 lb

Osmocote Smart-Release Plant Food Plus — compressed specs

Osmocote Plus is the benchmark controlled-release fertilizer. Each granule is coated in resin; water moves through the coating and dissolved nutrients seep out at a rate governed mostly by soil temperature. That means feeding picks up as plants grow faster in warm weather and slows in cool weather, which is exactly what container plants want. The “Plus” formula adds micronutrients, which matters in soilless potting mixes that contain few on their own.

It’s the only pick here that the listing describes as suitable for virtually everything: houseplants, patio pots, roses, shrubs, raised beds. Three sizes of the same formula appear on this shelf; the 8 lb tub is the practical choice if you fill more than a handful of containers each spring, while the 1 or 2 lb size suits a balcony. Compared with the Flower & Vegetable version below, it feeds longer but the listing doesn’t state the NPK ratio.

Check Osmocote Plus Outdoor and Indoor price on Amazon

2. Osmocote Smart-Release Flower & Vegetable — Best for Vegetable Beds

Best for vegetables

Why We Like It

• Highest total nutrient formula Osmocote lists
• Clear rate: one scoop per 4 sq ft
• Listing says up to 3x over-application won’t burn
• Good for mulched shrub and tree beds

Specification	Details
NPK	14-14-14
Release type	Temperature-controlled coated granules
Rate	1 scoop per 4 sq ft, mixed into top 1 to 3 in
Coverage	1 lb per 40 sq ft; 8 lb covers 320 sq ft
Duration	Up to 4 months stated on the 4.5 lb listing

Osmocote Flower & Vegetable — compressed specs

Vegetables are heavy feeders, and a balanced 14-14-14 gives tomatoes, peppers, squash and leafy greens a solid base without the nitrogen overload that pushes leaves at the expense of fruit. The listing gives one of the clearest application rates on the shelf, which helps avoid the most common mistake with granular feeds: guessing. It’s also listed for mulched areas around ornamental trees and shrubs, so one tub covers the vegetable patch and the foundation beds.

The same formula is also sold in 2 lb and 4.5 lb sizes on this shelf. Against GroMaster’s 10-10-10, it has more nutrients per pound and coated release, while GroMaster is the simpler, cheaper-per-bag option for large plots.

Check Osmocote Flower and Vegetable price on Amazon

3. Miracle-Gro Shake ‘N Feed All Purpose — Best Easy Shaker for Containers

Best for containers

Why We Like It

• Shaker lid makes spot feeding pots easy
• Includes micronutrients
• Natural ingredients feed soil microbes
• Simple reapply-every-3-months schedule

Specification	Details
Release type	Continuous release granules
Duration	Up to 3 months
Coverage	Up to 30 sq ft per 1 lb
Use	Containers, in-ground and raised beds
NPK	Not stated in listing

Miracle-Gro Shake ‘N Feed — compressed specs

Shake ‘N Feed is the most convenient pick for people who feed a few pots, hanging baskets and window boxes by hand. You shake granules over the soil, scratch them into the top inch, water, and repeat every three months. Its blend also includes natural ingredients intended to feed soil microbes, which sets it apart from the pure resin-coated Osmocote products.

The trade-off is duration and coverage: three months rather than Osmocote Plus’s six, and a 1 lb jar covers about 30 square feet versus Osmocote’s 37 for the same weight. For a summer of annuals in pots, three months is often all you need.

Check Miracle-Gro Shake N Feed price on Amazon

4. Scotts All Purpose Flower & Vegetable — Best for In-Ground Flower Beds

Best for flower beds

Why We Like It

• Good coverage, about 150 sq ft per bag
• Labeled for flowers, vegetables, trees and shrubs
• Sprinkle-and-rake application
• Steady feed through a growing season’s peak

Specification	Details
Release type	Continuous release nitrogen
Duration	Up to 2 months
Coverage	About 150 sq ft per 3 lb bag
Use	Outdoor in-ground plants
NPK	Not stated in listing

Scotts All Purpose Flower & Vegetable — compressed specs

This is a straightforward bed fertilizer for borders of annuals and perennials, vegetable rows and shrubs. Its two-month feeding window is the shortest on our list, but it covers more ground per pound than the Osmocote and Miracle-Gro products, which makes it practical for large in-ground beds you feed in spring and again in early summer.

The listing is specifically for outdoor in-ground plants, so for containers we’d pick Osmocote Plus or Shake ‘N Feed instead.

Check Scotts Flower and Vegetable price on Amazon

5. GroMaster 10-10-10 All Purpose — Best Value for Large Gardens

Best value

Why We Like It

• States its slow-release share: 50 percent of nitrogen
• Low chlorine, low salt blend
• Micronutrients included
• Resealable bag keeps granules dry

Specification	Details
NPK	10-10-10
Release type	50% slow-release nitrogen
Duration	Up to 3 months
Size	5 lb resealable bag
Use	Vegetable gardens and mixed plantings

GroMaster 10-10-10 — compressed specs

Many “slow-release” fertilizers are really blends: part of the nitrogen is in a fast form for an immediate green-up, and part is in a slow form that feeds over weeks. GroMaster is upfront about the split, listing half its nitrogen as slow-release. That gives vegetables a quick start plus steady feeding for up to three months. Its low-chlorine, low-salt formula is a plus around seedlings and salt-sensitive crops.

Compared with the GARDENWISE 10-10-10 on the same shelf, which is sold in a 1 lb size and lists about 8 weeks of feeding, GroMaster lasts longer and comes in a more practical quantity for a full vegetable garden.

Check GroMaster 10-10-10 price on Amazon

6. The Grow Co Indoor Plant Food — Best Granules for Houseplants

Best for houseplants

Why We Like It

• Urea-free balanced macro and micro nutrients
• Suited to bark, moss and perlite mixes
• Small 5 oz size fits a houseplant collection
• Sprinkle or poke into holes

Specification	Details
Release type	Slow-release granules
Duration	Months at a time (exact period not stated in listing)
Formula	Urea-free, macro and micronutrients
Size	5 oz
Use	Indoor and outdoor potted plants

The Grow Co Indoor Plant Food — compressed specs

Houseplants grow slowly and sit in small volumes of mix, so they need gentle feeding. This urea-free granule is pitched at exactly that, and the listing specifically mentions pots with bark, sphagnum moss and perlite, which covers the chunky aroid and orchid mixes that many general fertilizers don’t address. Osmocote Plus is also labeled for indoor plants and is a fine alternative if you already own a tub.

Check The Grow Co Indoor Plant Food price on Amazon

7. RAINFLOW Plant Fertilizer Sticks — Best Spikes for Potted Plants

Best spikes

Why We Like It

• No measuring, no spilled granules
• Listed to feed for up to 6 months
• 90 sticks cover a big plant collection
• Gentle no-burn formula claimed

Specification	Details
Form	Fertilizer sticks
Count	90
Duration	Up to 6 months
Use	Houseplants, orchids, herbs, potted vegetables and flowers
NPK	Not stated in listing

RAINFLOW fertilizer sticks — compressed specs

Spikes are the tidiest way to feed potted plants: push one or more into the mix near the pot edge and forget about it. They’re popular for indoor plants because there’s no dust or loose granules. The limitation is that nutrients concentrate around each stick rather than spreading evenly through the root zone, so use more sticks spaced around larger pots. If you prefer granules, The Grow Co is the comparable indoor option.

Check RAINFLOW Fertilizer Sticks price on Amazon

What to Look for in a Slow-Release Fertilizer

Coated vs uncoated release

Coated (controlled-release) fertilizers wrap each prill in resin or polymer; release depends mainly on soil temperature and lasts the longest, typically 3 to 6 months or more. Uncoated slow-release products rely on less soluble nitrogen forms or organic materials broken down by soil microbes, so they feed for weeks rather than months and depend on soil warmth and moisture. If you want one feeding per season in containers, choose coated. If you feed big beds twice a year, an uncoated blend is fine and often cheaper per square foot. For a deeper look at the trade-offs, see our slow-release vs quick-release fertilizer guide.

NPK and micronutrients

Balanced formulas like 10-10-10 and 14-14-14 suit mixed plantings and vegetables. Potting mixes are mostly peat, coir and bark with almost no micronutrients, so container plants benefit from formulas that list iron, manganese, zinc and the like. Our explainer on NPK fertilizer numbers covers how to read the bag.

Duration in real conditions

Label durations assume moderate temperatures. In a hot climate, or in black plastic pots baking on a patio, coated granules release faster, so a six-month product may be spent in three to four months. In cool spring soil they release slowly, which is why some gardeners give spring transplants a single dose of liquid feed to get going.

Granules vs spikes vs shakers

Granules mixed into the root zone give the most even feeding. Shakers are best for topdressing established pots. Spikes are clean and convenient indoors but feed unevenly. For trees and large shrubs, spread granules across the area under the drip line rather than piling them at the trunk.

How to Use Slow-Release Fertilizer

• Containers: mix the label rate into fresh potting mix at planting, or scratch it into the top inch of established pots, then water well. Don’t double up with a mix that already contains fertilizer until it’s spent, usually after about two to three months.
• Vegetable and flower beds: broadcast at the label rate per square foot and rake into the top 1 to 3 inches before planting. Reapply mid-season if the product’s duration is shorter than your season.
• Shrubs and roses: apply in spring as growth begins, spreading granules evenly from near the stem out to the drip line, then mulch. Avoid feeding woody plants after late summer in cold zones so new growth can harden off.
• Houseplants: feed in spring and early summer when plants are growing; skip winter feeding for most species.

Slow-release granules pair well with an occasional liquid feed when plants need a fast boost, such as heavy-fruiting tomatoes in midsummer. Our comparison of slow-release vs liquid fertilizer explains when each makes sense, and the composting and soil guide covers building fertile soil so you need less fertilizer overall.