Annual bedding plants are surprisingly more popular among those who enjoy gardening less. Those who procure the services of gardeners appreciate the rich colors and simple efficiency of annuals. Many who are more directly involved with their gardening consider them to be decadent. Nonetheless, warm season bedding plants will soon be in season.
Cool season bedding plants should perform well until the weather becomes too warm for them. There is therefore no rush to replace them yet. Besides, it is likely still a bit too cool for mature warm season bedding plants to be out in the garden. However, seed for warm season bedding plants takes time to grow. Some should start now to be ready for spring.
For example, petunia, impatien and zinnia are some of the most popular of warm season bedding plants. Almost all of them arrive at their respective gardens as somewhat mature plants within cell packs from nurseries. Presently, such plants may be vulnerable to frost. However, seed of these plants that begin now should start to grow after the threat of frost.
Not many of even the most avid of garden enthusiasts grow these popular warm season bedding plants from seed. Yet, a few do so. Some unusual or rare plant varieties are only available as seed. Many common wildflowers and ‘true to type’ annuals provide seed for subsequent generations. Such seed generally start in flats with shelter from frost indoors.
From flats, seedlings may graduate to cell packs or small pots prior to transitioning into a garden. Some should actually begin within cells rather than flats. Seedlings relocate into a garden when adequately mature, whether from flats, cells or pots. Seed for many warm season bedding plants perform best directly in the garden though, without transplanting.
Nasturtium seedlings do not grow well within the confinement of cells. Then, they remain somewhat pekid for a few days while they recover from transplanting into a garden. They grow so much more efficiently from seed sown directly into a garden. Marigold can grow about as well from seed directly in the garden as they can as seedlings that grew in flats.
Tony Tomeo 
In my zone, it’s best in MOST cases to start seeds indoors while waiting for the ground to warm up enough. While I’ve read that nasturtiums don’t like to be transplanted, I’ve done it with good results, and I get earlier blooms for my efforts. The growing season for flowers is too darn short in Zone 5!
LikeLiked by 1 person
This is an awkward subject for me. I try to write in such a manner that the information is relevant to the extremes of the region in which my garden column gets published. Much of that region is similar to the Santa Clara Valley, but a small portion of it where many readers reside extends into the Los Angeles region. Frost is irrelevant to many within that portion of the region.
LikeLike