This is a worthful division of garden plants , for by the biyearly riding habit of lay in up in the first time of year a reserve which is expended wholly in the second season , a much dandy amount of bloom is possible than with either the annual or perennial riding habit of growth .
It is also notable that many of our authoritative vegetable crop are in this family ; though where these are touch on ( for example loot , common beet , white turnip , etc . ) the plant is not let to blossom and seed but the nutrient salt away up for these affair are engage for culinary use .
Where a raw garden is being made annual and biennial plants will be of great service , for it generally takes from three to five years to achieve a garden provide satisfactorily with perennials and shrubs ; and even then biennial will still be needed .
The chief drawback to the finish of biennials is the space which must be give to them in the reserve garden or flesh since they are not make a motion into their terminal stations until they are large intelligent plant .
The term biennial is not used too strictly by the nurseryman and some light - last perennials , some monocarpic plant and , certain annuals also are sometimes give biennial treatment .
Cultivation
biennial may be sown in spring in a frame or cold greenhouse or alfresco in beds of all right weed - free soil from May onwards .
If seeds are sown in drills instead of broadcast it will be light to keep them free from weeds by running the hoe between the rowing from sentence to time .
After severe cutting seedling should be crowd on with equal eating until by October , they will be bombastic , leafy plants , which may then be put into their final stations in the flower border . If the weather condition is dry when the fourth dimension comes to graft give the bed a thorough watering . Careful lifting , using a trowel , will minimize root disturbance , and subsequent checks to growth .
If it is mean to treathardy annualsas biennial ( excellent result in mild areas ) the only way in which the operation differs from that described above is at the time of the seed sowing , which should be at the closing of the summertime or even in other autumn , but do not sow too early or the plants will flower in their first class . give this biennial discourse , annuals will make much gravid plants than when grown in the normal way and this must be allowed for when they are planted out in their last positions .
Half - intrepid biennial will need over - wintering in icing - free condition in a frame or a cold greenhouse . They are not an important plane section and one may well do without them , devoting precious glasshouse space to other thing .
The adopt are biennial , or are often treated as biennial : adlumia , althaea ( hollyhock ) , genus Antirrhinum ( snapdragon),Campanula medium(Canterbury bell ) , cheiranthus ( Erysimum cheiri ) , cnicus ( fishbone thistle),Dianthus barbatus(sweet william),Digitalis purpurea(foxglove),Erysimum arkansanum , Hedysarum coronarium(French honeysuckle),Humea elegans(half - hardy ) , hunnemannia , lunaria ( honesty ) , matthiola ( Brompton , Nice and intermediate Malcolm stock ) , some meconopsis , genus Myosotis , Oenothera biennis(evening primula ) , onopordon ( cotton thistle),Papaver nudicaule(Iceland poppy ) , verbascum ( mullein ) .
