1. Garden Cosmos, Mexican Aster (Cosmea)

The frost-sensitive Cosmea need to be started indoors. This has the advantage that the plants will be bigger and stronger when they are planted outside and will not be eaten by snails as quickly. They also flower earlier compared to those which you sow outdoors from May onwards.

Sowing: Sow the seeds in pots or seed trays and cover with just a little soil. Keep the soil moist until the seeds germinate. Mist the soil to prevent the seeds being washed away. When the young plants have four leaves you can transplant them into pots. From the beginning of May, place the plants outdoors in a sheltered, shady spot during the day to harden them. From mid-May they can be planted in the garden. Space the plants 10 inches apart.

2. Edging Lobelia, Garden Lobelia or Trailing Lobelia (Lobelia erinus)

The Edging Lobelia not only has pretty blue flowers, but is also low maintenance plant. It produces a lot of nectar, making it an important bee-friendly plant for the garden or balcony.

Lobelias are balcony flowers that need plenty of sun and prefer a warm, sheltered spot. They have few substrate requirements and will grow in normal potting soil.

Sowing: Lobelia seeds are light germinators, so scatter them lightly over the soil. Cover the pot with a plastic sheet to prevent the seeds from drying out. In a warm, sunny spot, the first seedlings will appear within a few weeks. When the plants have two pairs of leaves, transplant them into pots. The young plants need to be hardened off before being planted outdoors.

3. Marigolds (Calendula)

Marigolds are like little suns in the garden. These plants not only brighten our mood, they are also very useful. They are flowers that should be in every flower bed, because they attract pollinating insects. The flowers are edible or you can make a soothing calendula ointment.

Sowing: As marigolds are light germinating plants, the seeds are covered with just a little soil. After about three weeks of germination, the marigolds are pricked out and placed in a cool but frost-free place.

4. Carnations (Dianthus)

Dianthus are very popular because they flower for so long. There are many varieties that come in different colours such as red, white, pink or multi-coloured. Carnations grow best in a sunny position.

Sowing: Sow carnation seeds in seed trays. In temperatures between 15 and 20 degrees, the seeds will germinate in about one to two weeks. After a further two weeks or so, transplant the seedlings into pots and plant out in mid-May. Make sure the plants are planted about 8 inches apart.

5. Petunias

Petunias are long-flowering plants for window boxes or beds. If you start them indoors, you can enjoy the flowers from mid-May.

Sowing: As petunia seeds are very fine, sowing is easier if you mix the seeds with quartz sand and then scatter them in planting trays. The soil should be well compacted and watered. Cover the seed tray with a sheet and place it in a bright, warm spot near a window. When the second pair of leaves has formed, prick out the plants and transplant them into pots. Petunias can be transplanted outdoors from mid-May.

6. Sweet Alyssum (Lobularia maritima)

The fragrant sweet alyssum is a charming, cushion-forming plant that flowers continuously from May to October. It is native to the Canary Islands, where it grows as a perennial. It is not hardy, so we only grow it as an annual.

Given its origins, the fragrant Sweet Alison loves a sunny, warm location and well-drained, chalky soil.

Sowing: The simplest method is to sow five seeds in a seed pot. Place the seed pot in a sunny spot near a window and keep the soil evenly moist. From mid-May, Lobularia maritima can be transplanted to its new home in the garden or on the balcony.

7. Zinnias (Zinnia)

Zinnias are beautiful summer flowers that look particularly good in cottage gardens and mixed borders. The nectar-rich flowers are particularly popular with bees. Make sure you sow unfilled or semi-filled varieties, as the nectar in filled varieties is difficult for bees to reach. Zinnias love a sunny spot sheltered from the wind.

Sowing: Sow seeds about half an inch deep in seed trays. Make sure the seeds are well covered with soil as zinnias are dark germinating plants. Place the seed tray in a bright, warm spot and keep the soil moist. After about three weeks you can transplant the seedlings into pots.