How to Grow On Plug Plants

01/14/25

7-8 Minutes Read

When to Sow: Late Spring

Written By Johnsons Team

How to Unpack Your Plug Plants

When your Johnsons plug plants arrive, unpack them immediately and, if dry, allow your plants to soak in water until the compost is fully moist again. You may notice an initial slight yellowing of the foliage, but this is quite natural after they have been in a dark box and is nothing to be worried about.

Next, stand them in a bright, airy position, out of direct sunlight, where there is some gentle warmth. Each of our plants is carefully nurtured under ideal glasshouse conditions, so your plants are likely to be sensitive to both the cold and scorching sunshine when they first arrive.

Suitable places would be a conservatory, greenhouse, sunny windowsill of a cool room or well-lit porch. Aim to give them a minimum temperature of about 10C/50F - a little more for begonias and impatiens.

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40 standard plugs

How to Pot On Plug Plants

While your plants may need a day or two to acclimatise, they are otherwise ready to be potted as soon as possible. When doing so, gently ease each young plant from its cell, and if necessary, push it out by inserting a suitable thin implement through the hole in the bottom. Please be aware that larger plants will not need to be grown on but will still require protection from the frost.

If you’re planning to arrange your plants in beds, borders or immovable tubs later in spring, pot them on in multicell trays or 9cm pots with multi-purpose, peat-free compost.

With the exception of mini plug plants, plants intended for use in hanging baskets, flower bags, or pots can be planted directly into their final containers inside a greenhouse or conservatory. However, be mindful that this will take up a lot more room and will still generally need protection until all danger of frost is past. If you choose to transplant them into multicell trays or small pots first, we’d recommend leaving them for about 3 to 4 weeks before moving them on.

As soon as you have transplanted your plug plants, water them in well. Wait for the surface of the compost to dry before watering again - your plants are unlikely to thrive if overwatered. If you have to grow your plants in a place where they only receive light from one side, such as on a windowsill, be sure to turn them regularly so that they flower evenly.

Planting Out Your Plug Plants

One of the most important steps when it comes to planting out is hardening it off. Typically, the first week of May is the perfect time to harden off your tender plants, as the risk of frosts has passed. Stand your plants outside during the daytime and bring them in on cold nights before planting them in their final positions outside at the end of the month. Hardier varieties such as antirrhinums, delphiniums, sunflowers, pansy plants and stocks can be hardened off earlier if their root systems are strong.

Planting out in containers and baskets

When planting up your containers and baskets, we’d recommend mixing in water-retaining gel granules and a slow-release fertiliser with your compost. Not only will this benefit the growth of your flowers, but it will save you time with both feeding and watering later in the season. As a general rule, we’d advise you to allow one plant per 5cm/2in of container or basket diameter. Needless to say, larger growing plants like Nicotiana sylvestris will need more space.

Planting out in borders

If you are planting in your borders, prepare the ground well, removing any perennial weeds. Where the soil is not already rich, dig in well-rotted manure or compost. For optimum flowering, either incorporate some slow-release fertiliser or feed regularly through the season. Be sure to keep plants well-watered until they are established.

Shop Plug Plants at Johnsons

Now that you know how to grow on plug plants take a look at Johnsons’ premium selection of plug plants to bring new life to your growing space. We’re dedicated to offering the highest-quality plants that promise stunning blooms with undeniably vivid colour. Whether you’re a colour lover or are in awe of unique shapes and styles, Johnsons has plenty of plug plants to suit your taste and create statement arrangements.

Find out what to do in the garden now, or take a look at our growing help and advice blog for more gardening tips to enhance the style of both your interior and exterior spaces.