Even within its native range, blue dawn flower, Ipomoea indica, can be a problem. There are not many other plants in some coastal regions of Peru that can avoid getting overwhelmed by the aggressive wiry vines. These vines grow roots where they touch soil, so can spread indefinitely over the ground. Vines that succumb to frost over winter regenerate as if nothing ever happened.
Three inch wide flowers are rich purplish blue when they open at dawn. They then fade through the day, only to be replaced by fresh new flowers the following morning. Bloom continues from spring until autumn, and can get profuse at times. The lush rich green leaves are cordate (heart-shaped) or lobed (with only three lobes). Too much fertilizer promotes growth but inhibits bloom.
Blue dawn flower’s main weakness is a dependency on water. If it gets too dry briefly in summer, it can die back like it does with frost, and then recover once it gets water, but it will not survive for very long if it stays dry. As aggressive as it is, it should not spread very far from landscaped areas or riparian areas where summers are too warm and dry for it.
Why would anyone want to grow annual gazania when perennial gazania that is popularly grown as ground cover lasts for several years? Well, as long as the weather stays warm, annual gazania blooms with an impressive abundance of bigger and more brightly colored flowers. Perennial gazania blooms less profusely and only in midsummer, with simpler and somewhat smaller flowers.
We think of rhododendrons and azaleas as being from cooler and moister climates. After all, that is where they do best. Yet, there does happen to be a native western azalea, Rhododendron occidentale, that lives in the Sierra Nevada and coastal ranges from San Diego County to just southwest of Portland, Oregon. (Azalea and Rhododendron are varied specie of the same genus.)
This is one of those warm season annuals that we do not hear much about. Verbena looks something like lantana, but rather than maturing into a nice shallow ground cover or low mounding shrub with a bit of staying power, verbena lasts only until frost next autumn. The blooms are a bit larger. The leaves are a bit greener. They stay lower than a foot, and get only a few inches wider than tall.
Like Ginger and MaryAnn, choosing between the flashier hybrids of clematis and the anemone clematis, Clematis montana, might not be so easy. The fancier hybrids have the bigger, bolder and richly colored flowers that the genus is known for. Anemone clematis has smaller and more subdued flowers in soft pastel hues, but is more prolific, more vigorous, and blooms for nearly a month.
Rarely planted but often found where the wildflowers grow, rose campion, Silene coronaria, has a way of sneaking in like California poppy or sweet alyssum do. It is so rarely planted that young plants are rarely available in nurseries. Seed is somewhat more available in nurseries, and quite available online. Although they self sow freely if allowed to go to seed, they are not really invasive.
There are so many different specie involved with the extensive breeding of the modern cultivars of clematis that they are not even assigned full Latin names. They are simply known as ‘clematis’ (without a specie name), with a respective cultivar name. Clematis X jackmanii is the oldest known hybrid, so the name is often applied to other hybrids, whether or not they are actually related.
There is a reason why the most popular specie for frequently shorn formal hedges have small leaves and finely textured foliage. Technically, a formal hedge of cherry laurel, Prunus laurocerasus, can be shorn as well, but should be shorn only once or twice annually, and then allowed to fluff back out. Otherwise, the big leaves get shredded as quickly as they recover from previous shearing.
The pros and cons of wax privet, Ligustrum japonicum ‘Texanum’ might get it a rating of about 2.5 out of 5. It seems that every asset is offset by a liability. The profuse clusters of tiny white flowers are sweetly fragrant, but are also a serious problem for those allergic to pollen. The berries attract birds, but are also very messy, and contain seeds that can germinate in the strangest of places.
They are short term annuals in spring or autumn. Where winters are cold, they may last from spring through autumn. Where summers are hot, they may last from autumn through spring. So what are snapdragon, Antirrhinum majus, here? They can be either or both, depending on where and when they get planted. For most of us, they are a cool season annuals that finish before summer.