How to Germinate Seeds and Root Cuttings for a Successful Hydroponic Harvest
If you’re aiming for a bountiful Christmas harvest, the countdown has begun and with just under 100 days to go, now is the perfect time to start germinating seeds or rooting your clones. At Holland Horticulture, we help growers across the UK get the most out of every grow cycle with trusted advice and proven products. Whether you grow in soil, coco, or full hydroponic systems, this guide walks you through how to successfully propagate seeds and cuttings for a productive and healthy crop.
Starting Seeds: Best Methods for Indoor Propagation
Growing from seed indoors isn’t as simple as sowing them outdoors. If you’re germinating rare chilli varieties or valuable genetics, you’ll need the right tools and conditions. There are several methods direct to soil, propagation plugs like Root Riot, Rockwool cubes, or the damp paper towel method. Each approach has its place depending on your final grow medium.
Straight Into Soil or Coco
If you're growing in soil or coco, starting your seeds in small pots is a reliable method. Use a high-quality light soil such as Biobizz Light Mix to ensure your young plants aren’t overwhelmed with nutrients. Avoid pots larger than 1L to prevent overwatering and potential root rot.
Pro tip: Pre-soak your seeds for 6–12 hours in room temperature water. Fill your pots, moisten the soil with a spray bottle, and plant seeds ½” deep. Place your pots in a propagator under low-intensity propagation lighting like a T5 or CFL.
Using Propagation Plugs
If you're growing hydroponically or in coco, propagation plugs like Rockwool cubes or Root Riot sponges are ideal. Soak them in room temperature water mixed with Formulex or Shogun Katana Roots to encourage germination. Don’t squeeze the plugs, retain that oxygen!
Paper Towel Method
Although not our top recommendation for beginners, the paper towel method has high success rates when done correctly. Use high-quality towels that retain moisture and place them in a zip-lock bag in a warm, dark space like an airing cupboard. Once a taproot appears, carefully transplant to your chosen medium.
Rooting Cuttings: Cloning for Consistency
Using clones ensures consistency in genetics and growth traits. Here's how to take and root healthy cuttings:
Preparing the Cutting
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Choose branches from the top of a healthy mother plant in the vegetative stage (not flowering).
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Use sterile scissors or a scalpel to make a clean 45° cut.
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Remove excess fan leaves and lightly scrape the bottom inch of the stem to promote root formation.
- Dip the cutting in Clonex Rooting Gel to protect the wound and trigger root growth.
Inserting Into Medium
Place cuttings in pre-soaked Rockwool or Root Riot plugs moistened with Formulex or Katana Roots. Gently press the plug around the cutting for support and position inside a humid propagator.
Choosing the Right Propagator and Light
A good propagator will maintain ideal humidity and temperature. During colder months, consider a heated propagator. For aeroponic propagators offer exceptional root development using nutrient-rich mist.
Use blue-spectrum CFLs, T5 fluorescent lights, or PS1 propagation lights for gentle but effective illumination. Start with a 24-hour light schedule and reduce to 18/6 once roots develop. Avoid HPS or MH lighting in early stages as they produce too much heat.
Maintenance Tips for High Success Rates
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Keep temperatures stable at 20°C
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Humidity should remain between 80–100%
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Mist the inside of your propagator lid daily
- Remove the lid for 15 minutes each day to allow fresh air in
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Use root stimulants like Katana Roots to speed up development
Final Thoughts
Successful propagation starts with attention to detail. From selecting the right rooting media to choosing reliable propagation lighting, every step contributes to your final yield. Explore our Propagation collection to get the products you need for your next grow.
Need more help? Visit one of our four UK stores (Manchester or Huddersfield), or browse our blog for more tips.