The excitement of the growing season is upon us, and after the relative quiet of the winter months, it’s time to get busy in your greenhouse and garden.
You may already have a list of all the lovely vegetables and flowers you’re planning on growing. But in case you need some seeds of inspiration, here are some ideas to get you started.
What to grow in March?
If you’re looking for vegetables to start planting in March, there’s a long list of options. Our gardeners have a few favourites to recommend.
Vegetables to plant in your greenhouse in March
Radishes:
Radishes can be planted outside from April, but if you have a greenhouse, you can get them sown in March. There are many varieties of radish, with flavours ranging from mild to peppery, and colours including red, gold and purple. Choose the options that appeal most to you, and get ready to grow!
Radishes will grow best at 2.5cm (1 inch) intervals, and under a thin 1cm of soil. Remember to plant them in trays or containers that are deep enough for their deliciously crunchy bulbs to form.
Radishes are easy to grow and do well in lots of different settings. You can plant them in a container, pot or bed, and even place them in between rows of other vegetables, such as tomatoes.
Keeping the radishes cool and wet will prevent the plants from going to seed before you harvest them. Check your seed packet for specific information about harvesting – most varieties will be delicious on your plate within just three to four weeks of sowing.
Spring Onions:
If you’re sowing spring onions in a greenhouse in March, make sure you’re selecting a summer variety, as there are variants that thrive in the cool and others that will flourish as temperatures rise.
Prepare your soil before planting, by adding some fertiliser, and making sure it is moist. You can plant in seed trays to transplant outside later, or seed them straight into larger containers or pots in the greenhouse until they are ready to harvest. The seeds can be planted on the soil and then covered with a very thin layer of soil, just 15mm deep. They will do best when spaced 5cm apart, but you can thin them out later if your seedlings are closer together.
Spring onions need well-drained soil, because their roots will start to rot if they get waterlogged. So, choose containers or pots with good drainage holes. As they grow, water them enough to keep the soil moist, but be careful not to overwater.
Most varieties of spring onion will take around 8 weeks to grow, and be ready to harvest when they are about 15 cm tall.
Tomatoes:
While we’re on a salad theme, why not get your tomato seeds into the soil this March.
Choose your tomato variants based on where you’re planning to keep them. A vine might be bountiful all summer if you’re planning to keep it in the greenhouse, but if you’re looking to plant out into a raised bed or veg patch, a bush variant will be easier to manage.
Your seeds can go into trays and pots under about 1cm of soil. Keep them somewhere warm, but out of direct sunlight, until the seeds germinate. At this point, move them somewhere bright, keep them well watered, and enjoy seeing them grow by the day.
Depending on the variety you have chosen, you may need to stake or support your tomato plants as they grow. When the fruit are red and ripe, be ready to snap them up and get them onto your plate or into recipes.
Flowers to plant in your Greenhouse in March
If you’re all vegged-out, and looking to get a head start on some bright blooms, we have some flowers to recommend too.
Cosmos:
Joyful and plentiful, cosmos bring wonderful colour to any garden. Plant them in sectioned seed trays, with seeds per section, pushing the seed about 3cm deep before covering over. Keep them well watered in a sunny spot in your greenhouse until they germinate. If both seeds sprout in a section, remove one so that the other can thrive.
Keep them in full sun, and well-watered, and plant them out into larger pots when they are big enough to handle. If you want to encourage stems to branch, and produce more flowers, you can pinch out the growing tip once a stem has three sets of leaves.
They will be ready to plant out in May or June, into sunny spots, and will bring beautiful flowers from July to October.
Marigold:
As well as being cheerful and bright, marigolds benefit gardens by actually deterring pests. They grow brilliantly alongside vegetables, and some varieties are even edible.
If you’re planting marigolds in your greenhouse this March, choose a container that has good drainage and can be placed in a sunny spot. Make a shallow furrow and place the seeds a few cm apart, and cover with a thin layer of soil.
Marigolds are lovely bursts of colour and thrive in sunny beds. They will be ready to plant out once the threat of frost has passed, and will benefit from a week or two of hardening off as you move them out to their permanent outdoor position.
Rhino Greenhouse Tips – what to do in your Greenhouse in March
This is the season to start getting busy in your greenhouse.
With any luck, we’re past the worst of the icy mornings, but depending on where you are based in the UK, March can still be frosty. If you are overwintering plants in your greenhouse, they may need some attention now. If you had opted for horticultural bubble wrap or fleece to insulate your greenhouse, as daytime temperatures increase and daylight hours finally start to get longer, it may be important to check the plants have the right amount of moisture, and also that they are getting enough light. The tenderest of plants will still need protection, but hardier varieties may be ready to move outside towards the end of the month. On warmer and sunnier days, it may be time to air out the greenhouse. Just make sure you’re not dropping the temperature too much and giving any fragile plants a shock!
As much as it’s time to tend to your mature plants, March is most definitely the time to get new seeds in the soil. With any luck, your greenhouse will be delightfully full of green shoots by the end of the month. Check your seed packets as you grow, and take some time to think about the best placement for the different plants you’re sowing. Your south-facing side will be perfect for sun-hungry varieties, but may be too hot for others. A little bit of time to plan out your space, and where to grow what, may even inspire you to look for seeds or varieties you haven’t grown before, to make the most of certain shelves or corners.
If you were early out of the gates and have been sowing seeds already, you may be ready to move some hardy plants into the garden. Just remember to check whether they will need hardening off before you do, to give them the best chance of thriving in the transition to the flowerbed or veg patch.
You may have much-loved plants that you enjoy growing every year, but one of the absolutely joys of gardening is discovering something new. You could pick just two or three flowers or vegetables you’ve never grown before, and see how they get on in your garden. They may not thrive, but you never know – you might be thanking yourself later in the summer when your flowerbeds are brimming or you’re enjoying a tasty homegrown treat.