Knowing how petunias are grown can provide your garden with bright flowers that will continue to bloom from spring to the first frosts. Available in a wide variety of colors, petunias are very suitable for growing in flower beds, borders, windowsill boxes and other containers. Creeping varieties are particularly suitable for hanging pots.
Steps
Part 1 of 4: Getting started
Step 1. Choose your type of petunia
Although there are hundreds of petunia species, they all tend to fall into four basic categories, which are determined by flower size and growth habits. Some of these types of petunia are better suited to growing in a container, while others are better suited to the garden.
- Grandiflora have the largest flowers and are the most commonly used type of petunia. Some have single flowers while others double and come in straight and creeping varieties.
- Multiflora petunias have smaller but densely packed flowers and provide large splashes of color.
- Milliflora grow close to the ground and have small flowers. They are easy to control and work well for borders.
- Creeping petunias (Pendula) spread along the ground, from pots on window sills, and quickly cover large areas. This type will need to be watered more frequently.
Step 2. Select your petunias
After you have chosen the type of petunia you want, you will need to choose the species. There are a few things you should look out for when choosing the best plants for transplanting.
Choose planting petunia plants that are compact (not tall and thin) as they will thrive more easily
Step 3. Choose the right place to plant them
All types of petunias need at least five to six hours of full sun a day, although they can tolerate some shade. The soil needs to be well drained, although it doesn't need to be particularly rich in nutrients.
Petunias do well in containers, and even planted directly in the garden. However, if you plan to plant them in a container, you may want to make sure you use a compost made from peat moss, compost pine bark, or coir, as well as inorganic components such as sand
Step 4. Prepare the ground for the plant
Make sure you dig the soil so that it is loose and ready (allowing for better drainage). You want to both condition and fertilize the soil to prepare it for petunias. If you are planting in the garden, condition the soil with organic substances such as peat moss bales, well-rotted leaf compost, or manure. You will need to spread these organic substances to a thickness of 5-7 cm.
- Incorporate organic matter into the soil using a pitchfork to a depth of about 20-25cm. In this way you will also be able to break up a heavily clayey soil, allowing better water drainage, or to increase the ability of a sandy soil to retain nutrients and moisture.
- Fertilize your soil using a balanced fertilizer (such as 8-8-8, 10-10-10, or 12-12-12) in the garden soil. You will want to do this at a rate of around 1kg every 10m2. When the season changes (early-mid-July) you will want to try using a specific liquid fertilizer for flowering plants, every three weeks or so (but weekly for creeping petunias).
- Now, if you're using a windowsill box, or container, you'll need to mix slow-release fertilizer into the soil.
Step 5. Spatial correctly
Many petunia varieties require at least 30cm between plants in bright light. If you need to use a more shaded location, you can move them several centimeters (about 22-25cm) closer. There are some exceptions to this rule to keep in mind.
- Milliflora petunias can be arranged closer together than other types with just 10-15cm of space between them.
- Creeping petunias, on the other hand, should be spaced up to 45 cm apart.
Step 6. Plant them in the right season
You want to start transplanting plants in early spring to help them acclimatize outdoors. If you are planting them in the ground you should be sure to wait until the risk of frost has passed (or you can cover them at night to protect them from frost).
- The optimum soil temperature is about 15 ° C. If colder, the petunia will not bloom.
- If it's really hot, be sure to provide some shade for your petunias. Even if they love and thrive in the sun, too much can have an opposite effect on them.
Part 2 of 4: Growing Petunias from Seed
Step 1. Grow your seedlings
Petunias aren't very easy to grow from seed, but they can be done and usually for less! Start growing your seedlings 10-12 weeks earlier than you plan to transplant (ideal is early spring, and March in colder climates).
Try to get candy seeds, as they are easier to handle, especially for inexperienced gardeners. Petunia seeds can be difficult to manage due to their size, so keep this tip in mind
Step 2. Prepare the seeds to sprout
Petunia seeds need specific conditions to germinate. They need light and heat indoors (around 21-29 ° C), as they still can't resist outside.
- Sprinkle the small seeds on top of fresh, moist potting soil or sphagnum. Make sure you distribute them in moderation, so they don't take away space from each other as they try to grow.
- Press them gently into potting soil or sprinkle them with a light drizzle to sink them into the earth.
- Cover them with clear plastic wrap and store them in a bright, warm place away from direct light until they sprout (which usually occurs seven to ten days after planting them).
Step 3. Take care of the newly sprouted seedlings
When the seedlings begin to sprout, you need to remove the plastic film. Move them to a bright and cool place.
Move them to a brighter, cooler location after they sprout. The best temperatures are 17 ° C during the day, with night temperatures ranging between 13 and 18 ° C
Step 4. Place the sprouted petunia seeds under fluorescent light bulbs
You will want to place the petunias at least 10-15 inches under the lights. Make sure you put a timer on the bulbs so they stay on between 16 and 18 hours a day.
- Lift the lights as the seedlings grow, so that there is always 10-15cm of space between them and the lights.
- You don't have a particular need for expensive specific lights to grow plants. Normal fluorescent tubes are fine.
- Make sure the seedlings are placed directly under the bulbs (unlike before they sprouted, when the seeds had to stay out of direct light).
Step 5. Transplant the seedlings
You will know that the time has come to transplant them when they have three true leaves each. Then it's time to place them in their peat pot or in containers that house several plants each.
- Give them diluted fertilizer until the danger of frost has passed and you can plant them outside.
- Be sure to plant them in moderately fertile, well-draining soil.
Step 6. Fortify the young plants
You will accomplish this by moving the young petunias outside on sunny, warm days. When the night comes and the cold weather comes, bring them back inside so they stay warm.
After doing this for several days you can permanently plant them outside
Part 3 of 4: Taking Care of Your Petunias in Bloom
Step 1. Encourage new growth
Depending on the type of petunia you will need to prune the dead flowers and do some other work to encourage new growth and flowering of the side shoots. This way you will get more flowers.
- For Grandiflora and Multiflora, when they reach a height of about 15 cm, shorten them to encourage rapid formation of lateral shoots.
- Avoid topping Milliflora or creeping petunias.
- Cut the dead flowers. Keep your petunias blooming steadily throughout the season by removing faded flowers. Multiflora will not need this treatment. Reduce the plant by a third if it gets too overgrown and isn't flowering well. You will foster new growth and vigor.
Step 2. Give them the right amount of fertilizer
You need to make sure your petunia is healthy without overdoing the fertilizer. If your petunia foliage looks healthy and vigorous, but the petunia isn't blooming or doing it badly, you need to reduce the amount of fertilizer.
- Fertilizing the plants monthly is a good idea, as this will ensure good growth without overdoing the fertilizer.
- Double-flowered cultivars, however, should have a biweekly dose of fertilizer.
Step 3. Water them properly
Many types of petunia are quite easygoing when it comes to water. So a week's deep watering should be enough, unless the weather is incredibly dry. You need to wet them to a depth of 15-20cm each time you water them.
- Creeping petunias need to be watered more frequently (more than once a week).
- Petunias in containers also need more water depending on their size and the volume of soil they contain. Often these petunias need to be watered even once a day.
- A good rule of thumb is to allow at least the first 2.5cm of soil to dry out before watering again.
Part 4 of 4: Troubleshoot your Petunias
Step 1. Check for pests in the garden
You will see signs of aphids and caterpillars, pests that can destroy your petunias. You will want to get rid of them so that the flowers can continue to thrive.
- If you notice aphids, be sure to get rid of them by spraying the petunias with a strong stream of water. Keep doing this until all aphids have been eliminated.
- Watch out for small black droppings and holes in the leaves and flowers that could indicate the presence of caterpillars interested in your petunias. Treat them with an insecticide that doesn't harm the environment.
Step 2. Water fairly
Sometimes the new flowers will wilt before they actually bloom. When it happens it's because you aren't watering them properly. Allow the soil to dry out and water thoroughly.
Make sure you are watering at the base of the plant and not the plant itself
Step 3. Avoid petunia diseases
There isn't much you can do about diseases like mold and root rot. However, if you live in a rainy area, you may want to try planting the more water-resistant Multiflora rather than one of the species of the other types of petunia.
