Hostas and many of the grasses die out in the center leaving a bare space.  In spring dig them up and save the outside ring which you can cut up and replant into several new plants.  You will find the roots all tangled much like those of a houseplant left in a pot too long.

          Mums and the tall Asters roots get so tangled and mums sometimes try to grow on their old roots which can’t support the new plant which is usually bigger than the original plant.  They don’t form a definite circle in the center but do need to be divided nearly every year by taking the outside new plants that will soon make their own roots.  I like to “rotate” my crops” this way by moving the new babies into a different area where the diseases and insects have a harder time to find them. 

          Rhubarb is a long living perennial but many authors recommend dividing every 5 years or so to get a better crop.  The soil nutrients are used up early and the plant is a heavy eater so it can gradually decline if you just let it “sit”.  It can be divided in either fall or spring.  The plants will probably do better in spring as soon as the ground can be worked and you can find them.  They need to be about 3 feet apart in well drained sandy soil with a pH between 5 and 6.8.  Do not harvest the first year and lightly the second season.  Seed heads need to be pulled as soon as they appear.  The leaves are poisonous (oxolic acid) if eaten but can be used for mulch or put in the compost pile. If you have many plants you can dig some after heavy frost and put them in containers in a dark cool place for a month at least.  Then bring them out in light at 50-60 degrees F. Keep them moist and you will have early rhubarb.  But the plants will need to recuperate in the soil for at least two years.

          Helen’s flower (Helenium sp) is sometimes called sneezeweed.  It does not cause sneezing, and may grow as tall as 5 feet with many variations of its bloom color from solid yellow to bi-colors.  Like mums the roots get too crowded and the plant will gradually decline unless it’s divided.  I generally don’t leave them over two years in the same place. It is an early starter so can be divided either spring or fall.  I prefer fall after the first frost but before the ground freezes hard.  If I want to plant them in the same area, I dig a fairly large hole and add a good amount of compost to rejuvenate the moisture holding and add nutrients.

          Columbine’s are listed as “short lived perennials” at most 3-4 years.  They are heavy seeders but some colors are more aggressive than others if left alone. You may want to select the seeds of the colors you prefer. If the wild Canadensis is in your mix it wont take them very many years before they dominate the patch.  They are a red and yellow bi-color.  Here in Lincoln the plants seem to do better in partial shade.  Most of them are natives of high slopes and meadows.  They do come in many colors.  The only disease or insect problems I have had are leaf miners.  If it is not too bad I just pull off the individual leaves that have been “mined”.

          Delphinium live longer in an ideal garden (warm and not hot, humid and not dry) such as England or fog belts in the United States . They need cool, moist, well drained, very rich, and slightly acid soil. Here in Nebraska they need to be protected from hot winds. A favorite food of slugs or snails, they tend to break off during heavy rains or hail.  According to the editors of Sunset Magazine, “Even with the best care, modern hybrids tend to be short-lived perennials. Hardy to -35 degrees F. they must have a winter chill. As soon as they appear in spring, I put a cage around to try to keep them upright.  One author recommends starting seeds in summer and plan for only the next summer.  I did have one blue one live three summers!

          The purpose in life of a plant is to reproduce and have another generation do the same.  Many times you can prolong a plants life by dead-heading to stimulate them to make a new set of blooms.  Biennials such as Sweet Rocket (Hesperis matronalis) from Europe and China produces seed which drops in summer and comes up so that its second year is the next summer.  If you cut the flower heads off before seeds form (deadheading), that plant will come up the next year.  A number of biennials do this so you can control the number of plants for two years or more.  Since I like to “rotate my crops” I let the seeds mature, pull up the plant, and shake it in the new area. 

          Many of the bulbs function a little different.  If you let them mature their seeds, they will do so at the expense of the bulb.  Their seeds may not mature enough to bloom for several years so you will only have large flowers for one year.  This is why directions come with them to deadhead the blooms and keep the leaves standing to send “food” to the bulb.  Deeper planting also helps keep the bulbs bigger.  Tulips (hybrids) have this seeding problem but Jonquils do not, but both need that foliage.  Lilies need to be deadheaded leaving as much stem as possible.  It is recommended not to cut your lilies for bouquets every year or it weakens the bulb. 

          You need to know your plants and what they like!!!

Copyright 2008