Flower & plant seeds to sow in March – Sowing Guide

March is a pivotal month in the UK for gardeners and plant enthusiasts alike. As the grip of winter loosens and the first signs of spring emerge, it’s time to start sowing a variety of flowers and plants. This period marks a transition, bringing longer days and warmer soil temperatures, which are crucial for seed germination. 

Spring arrives at the end of the month, and there is gardening work to be done. And now that things are warming up slightly, you can sow some of these seeds directly outside, particularly if they are hardy annuals.

Let’s get stuck in.

These seeds are a great option

For March sowing, try the following seeds.

Borage

Also known as the starflower, this hardy plant is native to the Mediterranean and is known for its splendid leaves, which are gorgeous because of their shape and colour. Seed oil can also be extracted from its leaves. It has inspired great minds from Homer to Francis Bacon.

This plant is not keen on transplanting, but apart from that, it is quite easy to grow. You just need a spot in full sun or partial shade, and the soil needs to be well-drained. It will self-seed after flowering, and it looks great in a flower bed or a border.

Slugs can be a problem, so use beer traps or pellets. Powdery mildew will attack in some instances, so manage the problem by ensuring good ventilation.

Clarkia

There are around 40 species of clarkia, which is a hardy annual flower, and most are native to North America, though one species is native to South America. The petals of its flowers are not known for being ornate, but they are beautiful all the same as they can come in pink, purple, red, or white. The plant can grow 60 cm tall.

Sow these seeds in sunny position near a border or in a container. You should see flowers in a couple of months. Make sure the spot where you are sowing is weed free, and you should rake the soil to a fine tilth. Then, make drills that are 5 mm deep and which are spaced 15 cm apart. If the soil is dry before sowing, water and allow the soil to drain. Sprinkle the seeds and cover lightly. Water occasionally, especially if the weather is quite warm.

Dahlias

Dahlias are tender perennials pair beautifully with Angelica gigas, and they can flower in the first year. The Spanish first discovered this flower in Mexico, and it later became quite popular in Europe. They also attract pollinators like bees and beetles to your garden.

Dahlias can be sown in greenhouses in March, and the tubers, which can be dug up in autumn, can be stored for overwintering. Start off with compost and seed trays and cover with plastic. Germiantion takes two weeks. After that, place the seedlings into 10 cm pots. Use compost and water well.

Aphids, slugs, snails, and red spider mites are pests that can afflict Dahlias. Powdery mildew can also be an issue, so make sure there is enough ventilation.

Papaver commutatum ‘Ladybird’

This flower is a type of poppy that is native to parts of Iran and Turkey, as well as the Caucuses. It has distinctive red leaves with black spots. It will attract useful pollinators to your garden.

Sow this hardy annual in moist, well-drained soil, under full sunlight or in partial shade. It looks great in the front of a border and, in the right conditions, it will self-seed. It has a 55 cm height and spread.

Ammi majus

This plant is also colloquially known as ‘Bishop’s Weed’ and ‘Queen Anne’s lace’. The latter name arose because the plant has gorgeously light, frothy petals and its single red flower. According to legend, Queen Anne pricked her finger, and her blood forever stained the central flower.

Wild carrot seeds can be sown thinly and covered lightly with soil. It can grow in limey, well-drained and even infertile soil. In your garden, it can be a good idea to grow them around edges and borders as the disturbed soil will maximize their growing potential. It can grow 100 cm high and 50 cm wide. Remember to sow the seeds in full sun or partial shade. It looks great in the middle of a border, and it attracts bees and beneficial insects to your garden. 

Celosia

The name for this ornamental plant derives from the Greek word for ‘burning’, which is a name that has been inspired by the flame-like petals that adorn this plant. Another common name for it is ‘Prince of Wales Feathers’. In Africa, where the plant is native, it is eaten and cultivated a nutritious leafy green vegetable.

Sow these seeds in spot that attracts a lot of sunlight, though it can tolerate a bit of shade, preferably in rich, well-drained soil. Every few weeks, a balanced liquid fertilizer can be applied. Once grown, they are great as cut flowers, in pots, or in borders. Try growing the ‘Apricot Brandy’, ‘Flamingo Feather’, or ‘Kimono Mix’ varieties.

To extend the flowering period, you should deadhead regularly. To avoid fungal diseases, ensure there is good ventilation around the plant. Red spider mites are another potential pest, while aphid colonies should be crushed with your fingers or be blasted off by water from the garden hose.

Cosmos

These flowers come in a beautiful range of shapes and colours. Its name is derived from the Greek word for harmony, and it became mainstream when Spanish priests in Mexico noticed its evenly placed petals. These flowers are great at attracting useful pollinators. Even though it’s March, you should still use a heated propagator.

When it comes to germinating these seeds, light is your friend. Therefore, the seeds should be sown on top of seed compost in a tray. When they are big enough, they can be pricked out, and they look best in a border when they have been placed outside.

Aster

Aster is a perennial plant, and its name comes from the Greek word for ‘star’. In the UK, the ‘Sea Aster’ is the only native species, and in general, aster plants are known for their beautiful violet flowers. You can try growing the ‘Aster amellus’ or the ‘Aster frikartii’ varieties because these also thrive in UK conditions.

Ideally, the seeds should be sown in full sun or partial shade, in fertile and well-drained soil. If the soil has clay or grit, its quality can be improved through using well-rotted material. The height and spread of the plant varieties with the species, but they typically grow to a big size. Watering often will not be necessary and feeding twice a year will be sufficient. 

Remember to deadhead flowers when necessary.

Happy growing

Now it’s March, and we have so many options to choose from, from annuals to perennials. What is more, many of this flowers and plants are perfect for novices and experts alike.

Have fun!

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That’s why we created Gardeners Box, each month, receive the hand-curated seeds we recommend sowing right now to brighten your garden, along with detailed instructions, and plant markers all starting from just £9.99. Click here to find out more.