Surfinia: planting, watering, feeding and overwintering

In short: Surfinias are trailing petunias propagated by cuttings, so they are bought as plants, not seed. They are planted after 15 May in sun, 3–4 plants per metre of window box. In summer they need daily watering and feeding every week, and iron when the young leaves turn yellow. They overwinter in a bright room at 10–15 °C.

Surfinias are those balcony petunias that over the summer tumble from the window box in a dense curtain up to a metre long and flower until the first frosts. To look like that even at the end of August, they need more water and nutrients than almost any other balcony plant. Anyone who waters them "like pelargoniums" has scrawny plants with yellow leaves in July.

In this article you will find how Surfinias differ from ordinary petunias grown from seed, when and how to plant them, how to feed them and how to get them through winter or propagate them by cuttings.

Surfinia or petunia? What is the difference

Surfinia is a trade name of the Japanese company Suntory. It arose at the end of the 1980s by crossing petunias with a vigorous wild petunia from Brazil and reached Europe at the beginning of the 1990s. It was the first petunia that was propagated not by seed but by cuttings, and thanks to that it kept its strong trailing growth and resistance to rain. Today the name "Surfinia" is commonly used for all cutting-grown trailing petunias, including those from other breeders.

So do not buy Surfinia seed; nobody reputable offers it under that name. If you want to sow petunias, you will find the procedure in the article Want colourful petunias? Sow them right now, in winter! and an overview of the petunia groups in the article Petunias.

When and how to plant Surfinias

Surfinias do not tolerate frost. Put them outside after 15 May, in colder locations at the end of May. Keep plants bought in April until then on a bright windowsill or in a glazed loggia.

1. Container: the bigger, the better. Allow at least 3–5 litres of compost per plant. A shallow window box holds little water, and in July the plants dry out twice a day. A great help is a self-watering wick window box with a water reservoir.
2. Compost: good-quality compost for balcony plants with a pH of around 5.5–6.2. Cheap composts with a high pH are a frequent cause of yellowing.
3. Density: 3–4 plants per metre of window box, 2–3 plants in a hanging basket 30 cm across. An overcrowded window box looks good in May and is starving in August.
4. Pinching out: when planting, pinch the tips of the shoots by 1–2 cm. The plant branches more and the trail will be denser.
5. Position: full sun, at least 6 hours a day, a south-facing balcony is fine. In partial shade they flower less. Surfinias tolerate wind too, but in a draught at the corner of a house they dry out even faster.

Hang the window box on sturdy window box hooks; a fully watered and overgrown window box weighs tens of kilograms. How to choose a container is discussed in the article Don't be a window box, get the right flower pot!

Watering and feeding: the two things that matter most

Watering

In May and in cool weather water when the surface of the compost has dried. In summer in the sun Surfinias need water every day, on tropical days both morning and evening. Water at the base of the plants until water starts to run out of the drainage holes, and pour away the water in the lower saucer after half an hour. Permanently wet roots rot just as reliably as dry ones wither.

Feeding

Over a season Surfinias grow from a small plant into a curtain a metre long and use a huge amount of nutrients. Feed:

• from 2 weeks after planting until the end of August,
• once a week with liquid fertiliser in the water, according to the instructions, not stronger,
• with a fertiliser for balcony plants, for example BIOPON for pelargoniums. On the label look for trace elements including iron.

If you add a slow-release fertiliser to the compost at planting, a liquid fertiliser every 2 weeks is enough.

Why Surfinia leaves turn yellow

The typical picture from July: young leaves at the ends of shoots are yellow and the veins stay green. It is not a disease but an iron deficiency. Petunias cannot take up iron at a compost pH above 6.3–6.8, even when there is plenty of it in the compost. A high pH is caused mainly by hard tap water, which is used for watering every day all summer.

• water with rainwater whenever possible,
• use a fertiliser with chelated iron,
• in strong yellowing a separate iron product used according to the instructions helps.

When, on the contrary, old lower leaves turn yellow and the whole plant fades, nitrogen is lacking: you are feeding too little or too seldom.

Summer care: rejuvenation and faded flowers

Modern Surfinias mostly drop faded flowers themselves and do not form as many seed pods as old petunias. Even so, they flower better if you occasionally pull off withered flowers together with the seed pod.

In the second half of July the shoots often stretch, are bare near the window box and flower only at the ends. Then shorten them by about a third, water and feed. In 2–3 weeks they regrow and in August and September flower at full strength again.

Pests and diseases

• aphids on the tips of shoots – wash off with water, in need a product against sucking insects,
• spider mites and thrips in heat and dryness – spotted, silvery leaves; showering and higher humidity help,
• whitefly – white flies under the leaves, yellow sticky traps,
• root rot – wilting in wet compost; improve drainage and do not overwater.

You will find more tips on balcony flowers that last until autumn in the article Balcony plants that will flower until autumn.

Overwintering and propagation by cuttings

Surfinias are in fact perennial, they just do not survive frost here. They can be overwintered in two ways:

Overwintering the whole plant

1. Before the first light frosts, usually in October, shorten the plants to 10–15 cm.
2. Move them to a bright room with a temperature of 10–15 °C, for example a staircase or a cool bedroom.
3. Water only a little so the compost does not dry out completely, and do not feed.
4. In March repot into fresh compost, put them in a warmer place and start feeding. Pinch out the new shoots.

Cuttings

It is simpler to overwinter young plants from cuttings. In August to September cut 5–8 cm long tip cuttings without flowers, remove the lower leaves and insert them in moist seed compost. Under a lid at 18–22 °C they root in 2–3 weeks, faster in a heated propagator such as the Garland OneTop L. Overwinter the rooted plants on a bright windowsill at 12–15 °C.

Surfinia varieties are protected by plant breeders' rights. Propagating them for your own balcony is fine; selling your own cuttings is not.

Frequently asked questions

When should I plant Surfinias outside?

After 15 May, once there is no risk of light frosts and nights do not fall below 5 °C. Leave plants bought earlier in the light in the flat and harden them off outside during the day.

Can Surfinias be grown from seed?

No. Surfinias are propagated only by cuttings and are bought as plants. From seed you can grow trailing petunias of other, seed-grown series.

How many Surfinias should I put in a window box?

3–4 plants per metre of window box length, 2–3 plants in a hanging basket 30 cm across. More plants compete for water and nutrients in summer.

Why are my Surfinia leaves turning yellow?

When young leaves with green veins turn yellow, iron is lacking, usually because of hard water and a high compost pH. When old leaves turn yellow, nitrogen is lacking and you need to feed more often.

How often should I feed Surfinias?

Once a week with a liquid fertiliser for balcony plants, from 2 weeks after planting until the end of August. With a slow-release fertiliser in the compost every 2 weeks is enough.

How do I overwinter Surfinias?

Shortened to 10–15 cm in a bright room at 10–15 °C with minimal water, or as rooted cuttings on a windowsill. In spring repot them and start feeding.

Recommended products

We do not currently have Surfinia plants on offer. The following are suitable for planting and care:

• FLORA self-watering wick window box 60 cm – the water reservoir helps to get through hot days without watering twice.
• BIOPON fertiliser for pelargoniums 1 l – a liquid fertiliser for balcony flowers for weekly feeding.
• Hoštické fertiliser for PELARGONIUMS 1 kg – an organic fertiliser for balcony plants when you want to feed less often.
• Window box hook 15 cm – a firm fixing for a heavy window box on the railing.
• Garland heated propagator OneTop L – for rooting cuttings in autumn.

Sources

• History of Surfinia (Suntory Flowers)
• How to prevent or treat iron deficiency in petunia and primula (AHDB)
• Diagnosing signs of high and low pH (e-GRO)
• Petunia × hybrida (NC State Extension Gardener Plant Toolbox)

Updated: 27 September 2026