Planting Pansies: Choosing Plants, Spacing and Getting Them Established

Pick short bushy plants, not the ones already in full flower

The tray that catches your eye is the one covered in open blooms, and it is usually the wrong one to buy. A pansy in full flower in its cell pack has spent its energy on those flowers instead of on roots, is very often pot bound underneath, and will sulk for weeks after planting while the plants beside it that went in with buds only get straight on with growing. Choose plants that are short, dense, dark green and carrying plenty of unopened buds, and pick off any open flowers as you plant them.

Turn a plant out of its cell and look at the root ball before you commit to a whole tray. You want white roots visible through the compost but not a solid mat circling the outside. If the roots have set into a hard spiral, tease the bottom third apart with your fingers before planting, or the plant will sit in the shape of its cell and never root out into the surrounding soil.

Reject anything with yellow lower leaves, a stretched pale stem, spotted foliage or a soft brown patch at the base. Pansies are inexpensive enough that there is no reason to plant a compromised one, and a plant carrying leaf spot or rot brings it into your soil for future seasons.

Soil, drainage and the timing of planting

Pansies want a free draining soil with plenty of organic matter in it and a position that does not stay waterlogged after rain. Fork in a two inch (5 cm) layer of well rotted compost across the bed before planting. On heavy clay, plant into a raised bed or a container instead of trying to improve the drainage in one season, because a pansy sitting in cold standing water through winter will rot at the crown no matter how well it was planted.

The timing that matters is soil temperature rather than air temperature. Plant while the soil is still warm from the previous season, roughly above 45F (7C), so the roots have four to six weeks of active growth before the cold shuts things down. Plants that go in early enough to root out properly stand hard frost, get through winter and flower from early spring. Plants that go in late, into cold soil, sit there without rooting, lift out of the ground when it freezes and thaws, and are often dead by midwinter.

That means planting in late summer or early autumn for an autumn to spring display in a mild climate, or in early spring as soon as the soil can be worked where winters are severe. In both cases the target is the same: several weeks of cool but not cold soil, which is when pansy roots grow fastest.

Set the crown level and space wider than looks right

Dig each hole slightly wider than the root ball and the same depth, so that the top of the root ball finishes flush with the surrounding soil. The crown, where the stems emerge, must sit at soil level. Plant it a half inch (12 mm) too deep and soil and mulch collect around the stems, they stay wet, and the plant rots at the base in the first prolonged damp spell. Plant it proud of the surface and the root ball dries out faster than the soil around it and the plant rocks loose in wind.

Space six to eight inches (15 to 20 cm) apart in the ground. That looks far too sparse on the day, and it is the correct distance, because each plant spreads to eight inches (20 cm) or more and the gaps close within a month. Planting at three or four inches (7 to 10 cm) gives you an instant effect and then a solid mat with no air moving through it, which is where downy mildew and leaf spot begin.

In containers you can plant closer, at four to six inches (10 to 15 cm), because the display is only wanted for one season and the compost is fresh. Accept that a tightly planted container exhausts its compost faster and needs feeding from about six weeks after planting, and that it must have free drainage holes and must never stand in a full saucer through a wet cold spell.

1. Prepare the whole bed, not each hole Fork two inches (5 cm) of well rotted compost through the top six inches (15 cm) of the bed. Improving individual planting holes in heavy soil creates sumps that fill with water.
2. Tease out circling roots If the root ball comes out as a solid spiral, pull the bottom third apart with your fingers. A plant left in the shape of its cell pack never roots out into the bed.
3. Plant with the crown at soil level The top of the root ball should sit flush with the surrounding soil. Firm the soil gently around it with your fingers, not your heel.
4. Water in thoroughly, once One proper soak at planting settles the soil against the roots. Repeated light sprinkles over the following week wet only the surface and encourage shallow rooting.
5. Pick off the open flowers Remove every open bloom at planting, taking the whole stalk. The plant puts that fortnight into roots instead, and flowers harder and for longer as a result.
6. Keep mulch clear of the crowns Mulch the bed to hold moisture and steady the soil temperature, but leave a two inch (5 cm) ring of bare soil around each stem.

The first month after planting

For the first three to four weeks the plants are rooting out and are at their most vulnerable. Keep the soil evenly damp over that period, checking with a finger rather than watering to a schedule, and water in the morning so the foliage is dry by nightfall. This is also the window in which slugs do their worst damage, so put protection in place at planting rather than after the leaves are shredded.

Hold off feeding for the first two or three weeks. A newly planted pansy given a strong feed puts on soft top growth before it has the roots to support it, and that growth is the first thing to be damaged by frost. Start a half strength liquid feed once you can see new leaves being produced, and continue every two weeks through the flowering season.

Pinch the growing tips out once when the plants are established and putting on new growth. Two shoots break below each pinch, which gives a bushier plant carrying more flower stalks, at the cost of a couple of weeks of delay. On plants set out in autumn for a spring display that delay costs nothing at all.

Record the planting date, the spacing you used and the position of each group. Pansies are planted at a time of year when little else is happening, so the notes are easy to skip, and the comparison between a bed planted early and one planted three weeks later is the most useful thing you will learn about your own garden.