How to Grow Half-Hardy Annuals from Seed

How was your weekend? I spent some time looking through photos of summer gardens this weekend for inspiration , & I’m pretty excited about the flowers I’m going to grow.

Last time I wrote about growing half-hardy annuals, plants that grow, flower, set seed then die in a season. This time it’s all about growing half-hardy annuals (HH’s) from seed, the more tender cousins of the hardies.

Please don’t be put off by the thought of tending delicate plants, HH’s are brightly coloured, fast-growing & very glamorous. In short, they make your garden sing & essentially, they just need planting later than hardy annuals.

Zinnias:

They remind me of French markets where you see bunches of them being sold along with vegetables.

 

Sunflowers:

I’m still amazed that all this grows from seed in a few weeks.

Cosmos:

How to sow half-hardy annuals:

They originate from warm climates, like Mexico, so they need to be sown & kept in a greenhouse, or on a light-filled window-sill & planted outside after all frosts have gone.

I sow them here in mid-April, 6 weeks before the last frost date, at the end of May.

• Fill modules or trays of 3 inch pots with good quality compost & water them.
• Thinly scatter the seeds over the surface of the compost.
• Cover with a thin layer of compost or grit & add the label.
• Then cover with a couple of layers of newspaper, lift & check daily & remove the paper when the seeds start coming through.
• Water gently if the soil starts to look dry, & turn them towards the light if they start leaning to one side. Probably every day on a window-sill.

Hardening off:

They need to gradually acclimatise to outside temperatures before being planted outside permanently. The contrast  between night & day can be too much of a shock. Placing them outside in the morning& bringing them back in at night gets them used to being outside. It’s easy if you have them in trays or they can be moved to a cold-frame & the lid opened each day.

At first this seemed like a bit of a faff, but now I think of it as relaxing pottering, especially at the end of a busy day.

Planting:

Plant them outside in a sunny spot, but do it in the afternoon when the heat of the sun has gone [remember what that was like!] so the change is not too much of a shock.

Remember to water them regularly when they’re young, & they’ll grow very quickly. They have to because they’re on a mission to produce seeds before they run out of time.

The seeds can be sown directly into the soil after the frosts, I did this with the zinnias I grew at the allotment. However, they’ll flower later & if the tiny plants are eaten by slugs or snails, there won’t be time to grow more this year.

More half-hardy annuals:

Cleome [spider plants] usually in whites or pinks, grow up to a metre tall & last well as cut flowers.

Nicotiana [tobacco plants] I like the lime-green & deeep red ones.

Buy seeds from Higgledy Garden here  & see how to grow annuals from seed here & how to plan ahead, what containers to use etc  here.

Any thoughts on growing half hardy annuals?

Jill

all photos: Jill Anderson