Martyn Cox with tray of seedlings

Getting started with seeds

Nothing beats growing plants from seeds, whether it’s vegetables, annuals or perennials. Apart from being highly rewarding, it’s an economical way to fill your garden with plants. If you’ve never sown seeds before, give it a go. Don’t worry, it’s much easier than you might think. Here is Martyn Cox’s guide to getting started with seeds.

What seeds need

Getting started with seeds needn’t be difficult. Most seeds are easy to germinate if they are given a combination of water, air, dark and warmth. For great results always start off with good quality seeds and make sure equipment is clean to avoid diseases. Seeds started off indoors are best sown into fresh seed compost, while those sown outdoors like weed-free soil that has been cultivated to leave a texture resembling coarse bread crumbs.   

Choosing what to grow

There are thousands of different plants that can be grown from seeds and deciding what to grow largely comes down to personal taste. However, if your looking for varieties that are really reliable, then look out for the RHS Award of Garden Merit (AGM) cup symbol. Anything bearing this internationally recognised standard of excellence has been tested to the max to ensure it has a good constitution and doesn’t require any specialist growing conditions or care. All of the seeds that we sell at Richard Jackson Garden have been awarded the RHS AGM.

When to sow

Many seeds can sown directly into the ground when the soil is warm and moist, usually from April onwards. However, it is possible to sow some vegetables in early spring if seedlings are protected with a cloche – among those to try are Carrot ‘Amsterdam Forcing 3’, Leek ‘Jolant’ and Broad bean ‘Aquadulce Claudia’.

carrot Amsterdam forcing
Carrot ‘Amsterdam Forcing 3’. Photo courtesy of Kings Seeds

Some plants are frost-sensitive and not suitable for raising outside until late spring or early summer. However, they can be started from seeds sown indoors in early spring, resulting in plants that will ready to go outside when there’s no longer any danger of frost. This includes fruiting vegetables and tender annuals.

Martyn Cox sowing seeds in grow bag
Frost-sensitive plants are not suitable for raising outside until late spring or early summer. Image: Louis Cox

How to sow indoors

Start by filling a 7.5cm (3in) pot with seed compost (make sure it’s at room temperature and not too cold), level and tap to settle. Lightly firm with the bottom of another pot, and then thinly scatter seeds on top. In my experience, most will germinate, so only sow one or two more seeds in case of loses. Cover with a fine layer of vermiculite, water and pop in a label. 

Ideally, put pots inside a heated propagator to germinate. If you don’t have one, place a clear plastic freezer bag over the top, secure with an elastic band and stand it on a light windowsill. When seedlings have started to nose their way above the vermiculite, usually within a week, remove from the propagator (or take the bag off) and keep compost damp. 

When seedlings are about 2.5cm (1in) tall, slip the rootball out of the container and gently break apart. Hold each seedling by the leaves at the base of the stem, gently lift up and lower into a small hole set in the centre of a 7.5cm (3in) pot of multipurpose compost. Ensure leaves are just above the surface, gently firm in and water. Put in a light place and move into a larger pots when necessary.

Sowing vegetables outdoors

Before sowing outdoors you will need to give the ground some attention. Use a fork to break up large lumps of soil, remove stones and roughly level the surface. Rake the soil in one direction until the soil has a fine, even finish – draw soil into hollows and break down mounds. Then rake in another direction, 90 degrees to the first. When you finish, you should have a flat and even surface. 

sowing seeds in drills
Sow seeds in shallow trenches or drills.

Sow seeds in straight, shallow trenches known as drills. Stretch out some string between two canes and then run the corner of a rake along the string to leave a furrow – the depth required will be stated on the seed packet. Sow thinly along the row and cover with soil. Large seeds can be planted individually with a dibber tool.

Watering seedlings

It’s important that indoor seedlings are raised in compost that is consistently damp but not too wet. I like to use a hand held sprayer to moisten compost – it prevents overwatering and doesn’t disturb these delicate baby plants. The soil outdoors can dry quickly during windy or warm weather, so water regularly with a watering can fitted with a fine rose sprinkler. 

watering seedlings with hand sprayer
Watering seedlings with a hand sprayer moistens compost without overwatering.

Thinning direct sown seedlings 

Outdoor seedlings need plenty of space to develop to full size. In order to achieve this, they will need thinning out to a specific distance when large enough to handle. All you need to do is pull up the seedlings you don’t need by hand. Carrots are best nipped off at ground level to avoid attracting carrot fly.

How to get bushier plants

Flowering plants grown from seed tend to form a single stem. To get bushier plants remove the growing tip when the seedling has formed four to five sets of leaves. Pinch off with your thumb and forefinger, just above a set of leaves. The plant will produce side-shoots from below. These in turn can be pinched back to get even bushier growth.

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