Plug plants are great value for money and will save time spent on sowing seeds.
They generally arrive with five to eight pairs of ‘true’ leaves, though this will vary between different plants and the plug size you’ve bought. They’re especially useful if you’ve left it too late to sow or don’t have the facilities to raise a lot of plants in the traditional way. They also require less heat and humidity than seeds, which is good news if you want to grow plants like petunias, nicotianas and French marigolds, which need a fair amount of warmth to germinate.
Most plugs are bought by mail order. Once they arrive, don’t plant them straight out in the garden – they’ll likely be eaten by slugs, snails and other pests. Unwrap them straight away and check they’re healthy and undamaged, then leave to soak in a tray of shallow water.
Once soaked, stand them on a bright windowsill, in a porch or a greenhouse, for a few days. Then, plant into trays of multi-purpose compost, or into small, individual pots. Water regularly at all stages, as the root balls will dry out quickly.
Discover Alan’s tips on growing plug plants, below.
Watering is key
As your plug plants grow their water requirements will increase. Feel the compost with your finger on a regular basis and give it a good watering whenever it feels slightly dry. Ensure they have a regular supply of moisture to produce even growth, but don’t allow them to sit in water for any prolonged period.
Sprinkling plug plants with a flower-head watering can
Look out for pests
Keep an eye out for greenfly. A small number isn’t necessarily a problem and will be kept in check by birds, ladybirds, hoverflies and lacewings. If aphids reach pest proportions you can blast them away with a jet of water from the hose.
Alan Titchmarsh inspecting plug plants
Keep your plants well ventilated so they don’t scorch in the sun. On really bright days, a sheet of newspaper or old net curtain draped over them will protect them. Horticultural fleece may exacerbate the problem, as it doesn’t allow much in the way of air circulation.
Trays of plug plants and potted-up plug plants
Pinch out any shoots that grow tall and leggy, to encourage bushiness, although many bedding plants branch naturally and won’t need such attention.
Pinching out tips of potted rosemary
Harden off your plants before you move them outside permanently. This simply means standing them outdoors during the day and bringing them back under cover at night. Ideally do this for a week or more to get them accustomed to lower temperatures. At the very least, make sure they’ve had plenty of fresh air. Water them just before planting, too.
Planting out beetroot plug plants
Plant them in their final location at a spacing that allows them to grow and spread. Also take steps to protect them from slugs and snails, which will eat tender, young foliage, even when they’ve reached a good size.
A tray of wildflower plug plants
Plug plants by size
Mini plugs – these measure 4-6cm from base to tip and are usually available early in the year, from mid-March. They need to be grown on for eight to 10 weeks before they’re ready to be planted outside
Standard plugs – also called medium plugs or simply plugs, they’re 6-8cm from base to tip. They’re on sale from April onwards and should be ready to go out after six to eight weeks
Jumbo plugs – also called garden-ready plugs, these are the largest, at 8-12cm from base to tip. Available in May, they can be planted straight into pots or hanging baskets outdoors once there’s no risk of frost