10x20 Kratky Hydroponics Tray Kit
Passive Hydroponics • Low-Maintenance
Tired of daily watering routines or worrying about your microgreens drying out when you're away for a few days? This Kratky hydroponics tray kit gives you a simple, passive growing system that keeps microgreens watered without pumps, timers, or electricity—just seeds, water, nutrients, and light.
Perfect for busy schedules, weekend trips, or growers who want the benefits of hydroponics without the complexity of automated systems.
What Is the Kratky Method?
The Kratky method, developed by Dr. Bernard Kratky, is a passive hydroponic growing technique where plants grow suspended above a nutrient-rich water reservoir. Unlike Deep Water Culture (DWC), the Kratky method uses no electricity, no pumps, and no air stones.
Plants naturally absorb water and nutrients as roots grow down into the reservoir while maintaining an air gap above the water line for oxygen exchange. It's hydroponics at its simplest.
Why it works for microgreens: Because microgreens have such short growth cycles (7-12 days from seed to harvest), they only spend 4-8 days suspended above the water reservoir. This brief contact period greatly reduces risks commonly associated with long-term Kratky growing, like root rot in mature crops.
How This System Works
During germination (3-5 days): Use the 1" no-hole tray for standard germination with blackout and weight. Seeds don't need the reservoir yet.
During growing phase (4-8 days): Transfer the mesh tray to the 2.5" deep reservoir tray filled with nutrient solution. Roots grow down into the water and absorb moisture as needed. The deep reservoir holds up to 14 cups of water, giving most crops 2-8 days between refills depending on variety and environment.
Result: Fewer daily water checks compared to traditional bottom-watering methods.
What's Included
Complete 5-Piece Kit:
- (1) 1" Deep No-Hole Tray (10x20): Heavy-duty tray for germination phase
- (1) 1" Deep Mesh Tray (10x20): Heavy-duty planting tray with drainage for growing phase
- (1) 2.5" Deep Reservoir Tray (10x20): Heavy-duty Kratky reservoir holds up to 14 cups nutrient solution
- (2) 10x20 Silicone Reusable Grow Mediums 1.2mm: Soil-free growing, works with small seeds
- (2) Microgreen Tray Clip Labelers: For labeling and easy tray separation (color may vary)
All trays are Bootstrap Farmer heavy-duty construction (1.8-2.0mm thickness, supports 50 lbs) made in the USA.
Individual components are also available separately if you need replacements or want to expand your system.
Why This Kit Works
Low-maintenance watering: Once set up, most crops go 2-8 days without refilling. Check water levels periodically and top up as needed—no daily watering routines.
Weekend-friendly: Step away for a few days without worrying about crops drying out. The reservoir keeps roots hydrated automatically.
No automation required: No pumps, no timers, no air stones, no electricity. Just water, nutrients, light, and plants.
Flexible growing media: Use the included silicone reusable grow mediums for soil-free growing, or use soil, coco coir, vermiculite, or another medium of your choice.
Durable construction: Heavy-duty Bootstrap Farmer trays built for repeated use. These aren't flimsy one-season trays—they're designed to last.
Easy hydroponics entry: Perfect introduction to hydroponic growing without the complexity or cost of automated systems.
Best For
- Busy growers who don't want to water daily
- Weekend travelers who need crops to survive 2-3 days unattended
- Hydroponic beginners wanting a simple system without pumps and timers
- Anyone seeking low-maintenance microgreen growing without sacrificing quality
Ideal Crops
Works great for most microgreen varieties with short growth cycles:
- Brassicas (broccoli, kale, cabbage)
- Sunflower
- Peas
- Radish
- Mustards
- And more
What You'll Need (Not Included)
- Microgreen seeds
- Hydroponic nutrients/fertilizer
- Grow light (if not using natural light)
- Tape and markers (for labeling)
- Water
Check our Free Fertilizer Ratio Guide for nutrient mixing instructions.
What Growers Appreciate Most
Customers often mention:
- The simplicity of the Kratky setup
- Fewer components compared to automated systems
- Thick, durable trays that hold up to repeated use
- An easy entry into hydroponics without added complexity
- Freedom to step away for a few days without crop failure
Care & Maintenance
Tray care:
- Hand-wash or dishwasher safe (top rack, no heat cycle)
- Do not expose to very hot water or steam
- Store out of direct sunlight when not in use to maximize lifespan
Silicone grow medium care:
- Scrape off roots with scraper ( purchased separately)
- Wash with warm water and free-and-clear soap
- Sanitize with boiling water (1-2 minutes) when switching varieties
- Air dry before storage
- Typical cleanup: 5 minutes per grow
Between grows: Clean all components thoroughly, dry completely, store properly.
Product Specifications
Tray Details:
- All trays are standard 10x20 size
- Heavy-duty construction: 1.8-2.0mm thickness
- Mesh Tray: 0.1475 inch mesh hole size
- Load capacity: 50 lbs per tray
- Material: Food-safe PP (Polypropylene) plastic
- Made in USA
Reservoir Capacity:
- 2.5" deep tray holds up to 14 cups nutrient solution
- Provides 2-8 days of passive watering (variety and environment dependent)
Grow Mediums:
- (2) 10x20 silicone reusable grow mediums included
- Works with small seeds without soil or coco coir
- Contains fiberglass core for structural support
- Food grade platinum-cured silicone
- 3rd party tested for FDA Compliance. LFGB Tested & Compliant.
- Silicone is rated for 20 to 30+ grow cycles per sheet with proper care
Labelers:
- (2) Tray clip labelers included
- Design by On The Grow®
- Color may vary
Important Silicone Grow Medium Information
Safety: Please review our Reusable Grow Medium Safety Disclaimer prior to purchase for complete safety information.
Fiberglass core construction: The silicone grow medium contains a fiberglass core for structural support. Replace your silicone if it develops tears, deep cuts, or significant wear that could compromise its integrity. For detailed guidance on when to replace, read our Silicone In-Depth Blog.
Staining: Silicone may develop stains with certain seed varieties (particularly beets and mustards). This is normal and doesn't affect performance or food safety.
NUTRITIONAL CONTENT DISCLAIMER: This product is an inert growing medium that does not add or remove nutrients from your crops. We make NO claims about nutritional content or nutrient density of microgreens grown using this product. Nutrient density depends on many factors outside our control including seed variety, water quality, light, fertilizers, and growing conditions - not the growing medium itself. We have not conducted laboratory testing and are not nutritionists. For complete nutritional disclaimer, see: [link to Safety Disclaimer page]
Warranty & Manufacturing
- Made in USA: All trays manufactured in the United States
- 1-Year Warranty: All On The Grow® tray kits backed by 1-year warranty
- Tray Clip Labelers: Designed by On The Grow®, patent pending in USA & Canada
What's Not Included
This kit does not include:
- Seeds
- Scraper Tool
- Nutrients/fertilizer
- Grow lights
- Tape or markers for labeling
- Microgreens or plants
You may find these blogs helpful:
-
Growing Microgreens Using the Kratky Method: A Comprehensive Guide
-
Silicone Reusable Microgreen Grow Medium - Complete Grow Medium Overview
-
How to Clean and Sanitize Microgreen Trays and Reusable Grow Mediums: Complete Guide
-
Microgreens and Mold: The Complete Guide to Prevention, Identification, and Treatment
-
Knowing the Right Time to Transition Microgreen Trays from Weight to Blackout
-
Common Mistakes When Growing Microgreens (And How to Avoid Them)
-
Looking for the Best Microgreen Growing Advice? Start with On The Grow
Simple passive hydroponics for microgreens—no pumps, no timers, just consistent results with minimal daily maintenance.