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Best Trailing Petunias For Hanging Baskets
A summer display of colourful, flowering bedding plants would not be complete without trailing petunias. These dazzling and versatile plants look great in beds and borders, pots and containers of all shapes and sizes
These trailing varieties look particularly stunning as they gently cascade over window boxes, in pots placed at the edges of decking and the traditional hanging baskets we see just about everywhere from June onwards. They are also good for use as an annual ground cover. Petunias are classed as tender perennials but are grown as annuals because they will not generally survive the first frosts.
There are many types of petunias, which tend to fall into 4 different groups. Grandiflora, Milliflora, Multiflora and Spreading. The spreading varieties include the trailing or cascading petunias. Typically, these are known as Wave, Surfinia, Tumbelina, Supertunia and Cascadia varieties. Some trailing petunias are grown from cuttings and sold as plugs, while others are grown from seeds.
Our Recommended Trailing Petunia Seeds
The Wave varieties however, can very easily be grown from seed, and petunia plugs from cuttings are quite expensive, so the focus here is on the seed grown, trailing “Waves”. For many gardeners, it can be difficult to distinguish between the varieties.
Wave trailing petunias comprise of an array of deep colours including red, purple and blue with white, pink and yellow also being available together with every shade in between. You have the option of buying seeds for plants of either one specific colour or a mixture of vibrant colours for your hanging baskets and tall tubs.
The seeds tend to be sold in pellet form, which means they have a coating around them made from a clay-like substance, which makes for easy handling and accurate sowing.
For best results, sow the seeds thinly or well-spaced, into trays of seed compost from mid-February to late April at a temperature of 18C - 21C. Apply water to the seed trays using a watering can and a light rose.
It’s important to ensure the seeds are not covered and the temperature is maintained until germination, so a greenhouse or heated windowsill propagator would be ideal. It’s also important to ensure the compost does not dry out before germination and so it’s recommended you cover the trays with cling film. Remove the cling film when the seeds have germinated.
Potting on and hardening off
When at least 3 true leaves have appeared they will be ready for transplanting to bigger pots or modular trays. Use a proprietary potting compost and carefully transplant the seedlings. Keep them watered and warm during this growing period. The seedlings will be quite tender and delicate at this stage so take care when handling and do not over water. The young plants should be placed in a light and airy position but not exposed to direct sunlight. The degree of light and warm temperature will determine how quickly the young plants will grow.
When the plant’s leaves or rosettes have reached the edge of the pot they will be ready to transfer to a cold frame for hardening off. It should take around 2-3 weeks for the plants to acclimatise and during this time they must be kept free from the effects of damaging frost. If frost is forecast then cover the cold frame with polythene or fleece to protect the young plants. The plants should be ready for planting out into beds, containers or hanging baskets towards the end of May when all danger of frost has passed.
If you intend to plant your trailing petunias into beds or borders for groundcover effect then the plants will benefit from a sprinkling of general NPK fertiliser into the soil at planting time. Plant them at 30cm apart. For all types of containers, use a quality potting compost and incorporate a general slow-release fertiliser. A large container will take 3 or 4 plants. Petunias prefer a sunny position, which will also encourage them to produce an abundance of flowers. Ensure plants are kept well-watered during dry spells.
Growing in hanging baskets
The Wave variety of trailing petunias will grow to around 120cm (4 feet) so you can expect a long cascade of colour all through the summer months. A 30cm hanging basket will take 3 or 4 petunia plants and there might just be enough room for a few trailing lobelia for added effect. Your hanging baskets will need lots of water, which should be applied daily, preferably in the evenings when the sun has gone down. A fortnightly liquid feed will keep the plants growing and flowering profusely.
Watering is obviously very important but so too is dead heading. By removing the dead heads regularly, you will encourage the plants to keep producing more flowers. The long trailing stems will produce blooms of up to 7cm in diameter, providing a breath-taking show of non-stop colour right up until the first frosts. Should the plants become straggly or outgrow their allotted space, they can be trimmed back if necessary.
Pests & diseases
During the very early stages of growth, the seedlings can be affected by damping off. This usually happens when the plants are exposed to cool and wet conditions, or you use a compost of poor quality, or one that hasn't been stored well.
Petunia seedlings need a steady 18C - 21C and careful watering during the first few weeks. Poor drainage can cause problems for petunias leading to root, stem or crown rot. Botrytis is another condition that can be caused by over-watering.
Powdery mildew can often be a problem towards the end of the growing season as the plants get bigger. In severe cases, applying neem oil can help reduce the spread of powdery mildew. Petunias can be affected by several viruses too, for which there is no remedy.
Pest problems can include mites, thrips, leaf miners and aphids, all of which can be treated with an insecticide. However, the worst culprits and the most destructive are caterpillars, slugs and snails. Hanging baskets should be safe from slugs and snails but containers will be a prime target. Beer traps and egg shells will provide safe and effective remedies.
What plants do you plant alongside Trailing Petunias? Let us know with a comment below....
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