Save money on summer bedding by buying plug plants. But how do you grow them on?

There’s still time to buy plug plants to fill your hanging baskets and containers, which can work out half the price of regular bedding.

It’s your last chance to buy plug plants, the baby plants which start off at around half the size – and half the cost – of the regular 9cm pot plants you buy later on in the season to fill containers.

They’re usually available until the end of April, but as the weather’s been cold this spring, the season is running three to four weeks later, which means there’s extra time to bag your bargain babies, says Tim Evans, horticultural buyer at Wyevale Garden Centres (wyevalegardencentres.co.uk).

Savings can be great, says Evans. “A 9cm-pot patio plant in a garden centre will range from £2 to £2.50, whereas the current plug price for a 4.6cm pot is about £1.30, or you can get cheaper multi-buys,” he says.

“You’ve probably also got the widest range of plants available from young plant suppliers at this time of year, which gives you greater flexibility to create your own mixes.
“And your finished product will be first to flower – and should last through the season if you feed and deadhead it regularly.”

Easier than growing from seed

While packets of seeds may be cheaper to buy, some plants are tricky or take a long time to grow from seed, including begonias, petunias, geraniums and dianthus, according to award-winning online garden retailer Thompson & Morgan.

What should you look for when buying plug plants?

The most important thing to look out for is a healthy root system, advises Thompson & Morgan. Evans adds: “Avoid plug plants which are stretched and straggly. You want something which is compact, a good shape and hasn’t gone yellow, which may mean they’ve run out of food, haven’t had enough light or have been too cold.”

Do you need a greenhouse?

“Not everyone has a cold greenhouse, so a lot of people pot plug plants into 9cm or 10cm pot and carry on growing them on the windowsill,” notes Evans.

Once the plant has filled the larger pot in a few weeks’ time, it should be ready to be planted into its final place outside, but don’t do this until the end of May or beginning of June, when all risk of frost has passed.

What do you do when you get them home?

Whether you buy them online or in store, remove them from their protective packaging and water them. Ease out the plants and the soil in which they growing all in one go by pushing up from underneath the container using your thumb or, if the plugs are very small, a pencil, so you avoid damaging the fragile stems or leaves.

Plant them on in larger pots as soon as you receive them and place them in in bright, frost free conditions under cover but out of direct sunlight. Before planting in their final spot outdoors, harden them off in a sheltered spot outside for seven to 10 days to acclimatise the plants.

What type of potting compost should you use to pot them on?

“Any good multi-purpose compost should be sufficient. Pot them on as soon as you can to get them established,” says Evans. “A lot of the plugs already have little roots sticking out of them and establish quickly once they are re-potted in a larger container.”

Don’t add feed at the initial stage of repotting, he advises. However, if you’re using plug plants for a hanging basket which you are planting up now and keeping in a cool greenhouse until the weather warms up, feel free to use a multi-purpose compost incorporating slow-release fertiliser, to help sustain the plants through the summer.

You can plant plugs straight into containers

If you have the space under cover, give your summer bedding a head start by planting your plugs into their final containers, but keep them in a sheltered frost-free place until the weather warms up.

Some garden retailers sell tough, large garden-ready plug plants which have already been hardened off and are ready to plant out when you receive them.

But if you have smaller plug plants that you are housing in an unheated greenhouse and the weather turns really cold, you may need to cover them with horticultural fleece at night to protect them.

What types of plants are available as plugs?

They are usually annuals, ranging from geraniums and bacopa to busy Lizzies, ageratums and fuchsias. You can buy perennial plugs from some online retailers as well as vegetables, including tomatoes, chillies and sweet peppers, and small pots of strawberries.
Are some plug plants better than others?

Cutting-raised plants tend to be more robust, says Evans: “Their ultimate garden performance is generally better than seed-raised varieties. Some plug plants don’t exist as seed-raised, such as fuchsias, bacopa and bidens.”