Potting On Plug Plants

Plug plants are young plants that need a little extra care before they’re ready for your garden or planters. “Potting on” simply means transferring them into a larger pot so they have space to grow strong roots before being planted outside.

Follow these steps for the best results:

What You’ll Need

• Clean pots or trays (with drainage holes)
• Good quality multi-purpose compost
• A dibber, pencil, or your finger for making holes
• Watering can with a fine rose
• A sheltered, frost-free growing space (greenhouse, cold frame, or bright windowsill)

1. Unpack and Water Immediately

• Unpack plug plants as soon as they arrive.
• Stand them in water for about 1 hour so they can rehydrate.
• They may look slightly dry or yellow after their journey — this is normal and they’ll quickly perk up.
• Place them somewhere bright, airy, and frost-free to help them acclimatise.
• For mixed plug collections, check the label on the outside of the packaging — it will match the letters embossed on each plug cell for easy identification.

2. Potting On

• Always handle plug plants by their leaves, not the stem, to avoid damage.
• Gently push plugs out from the bottom of the cell using a dibber, pencil, or similar tool.
• Use clean 9cm pots, shuttle trays, or windowsill planters filled with a good quality multipurpose compost.
• Make a hole large enough for the plug, insert the plant, and press in lightly — don’t compact the compost too much, as this can cause water to pool on the surface.

3. Preventing Damping Off

• Damping off is a fungal disease that causes seedlings to collapse at the base.
• It spreads through water, air, or contaminated pots and compost.
• To prevent it:
  • Ensure good air circulation.
  • Avoid overwatering and overly humid conditions.
  • Always use clean pots — wash reused ones with a disinfectant like Jeyes Fluid.
• If a plant becomes infected, remove it immediately and move healthy plants to a fresh, well-ventilated space.

4. Correct Watering

• Water in the morning so leaves dry before nightfall, reducing disease risk.
• Use tap water rather than water from a butt (which may contain fungal spores).
• Water only when the compost surface feels dry — or water from below to keep foliage dry.

5. Planting Out

• Wait until plug plants are strong, well-rooted, and all risk of frost has passed (usually late April/early May).
• Prepare the soil by removing weeds and enriching with compost or well-rotted manure.
• For beds and borders, space plants about 20cm (8") apart.
• For hanging baskets and containers, use a quality compost and add Swell Gel & Feed for longer-lasting results.
• Feed regularly with a high-potash fertiliser (e.g., Blooming Fast Superior Soluble Food) to encourage blooms.
• Deadhead regularly to keep flowers coming.

Tip: Always check your plants regularly — early care makes for stronger, healthier displays later in the season.

A full video planting guide is below:

Related products to help with growing and looking after your plug plants

1. Pack of 3 Windowsill Propagator Kits
2. Professional Shuttle Trays
3. Easy Fill Hanging Baskets 38cm (15in) Pair
4. Blooming Fast Swell Gel & Feed 250g