Depends on the type of lavender. The traditional English ones grow much bigger and quicker than the French ones for example.
If it is the English Augustafolia lavender I would plant one roughly every 75cm. The central part of the plant won't grow quite that big but the stems that come off it get really long. I've always found they grow best when they're not right up against each other as they tend to stop growing once they come into contact with other plants and you end up with a dead patch on the sides.
Make sure you trim them back this time of year to the bottom inch of green growth otherwise they get very woody very quickly.
Also I would actually recommend going for the bog-standard variety as the be found that it's the most reliable and toughest. When we had the beast from the east and all my lavenders got buried under a foot of snow I lost a few of the other varieties but none of the normal ones.
To be honest, you can't go wrong with buying cheap ones from B&Q or somewhere like that. Even the smallest ones will be full size in a couple of years. They're often reduced around this time too.
One last thing... When you plant them mix in some grit beneath and around them and try and plant them on a slight mound. And go easy on the compost. They don't like sitting in wet in winter. I made that mistake years ago. They don't like being moved/lifted higher later on either.
Check one of the specialist nurseries, my favourite one is Downderry Nursery. There are many types and varieties of lavender. You can choose only one variety and do it as a hedge or you could mix different ones to prolong the flowering season.
I would agree to try local and specialised nurseries as they desperately need support during these time. Large superstores by from overseas growers generally. I'm sure the local wildlife will thank you for planting a bed of lavender!
Posts
If it is the English Augustafolia lavender I would plant one roughly every 75cm. The central part of the plant won't grow quite that big but the stems that come off it get really long. I've always found they grow best when they're not right up against each other as they tend to stop growing once they come into contact with other plants and you end up with a dead patch on the sides.
Make sure you trim them back this time of year to the bottom inch of green growth otherwise they get very woody very quickly.
Also I would actually recommend going for the bog-standard variety as the be found that it's the most reliable and toughest. When we had the beast from the east and all my lavenders got buried under a foot of snow I lost a few of the other varieties but none of the normal ones.
To be honest, you can't go wrong with buying cheap ones from B&Q or somewhere like that. Even the smallest ones will be full size in a couple of years. They're often reduced around this time too.
I'm sure the local wildlife will thank you for planting a bed of lavender!