The fourth week of May is a when many spring bulbs have faded. Clip off the stems and blooms of tulips, daffodils and other bulbs to tidy up but leave the foliage to ripen and yellow as this is how the bulb sends energy to next year’s flower.
Get snippy this week with late blooming perennials such as sedum ‘Autumn Joy’ and chrysanthemums.
If you harden your heart and cut back the new growth of these perennials now, you will encourage branching from the cut stems and more compact plants with stronger stems and twice as many flowers.
Cutting off succulent new growth may be easier if you realize that the cut stems can be turned into new plants. Just remove the lowest leaves and insert the cut stem into moist soil. Not all the new cuttings will root but what have you got to lose?
Depending on the weather and your soil, gardeners in Western Washington have had good luck making simple cuttings of lavender, boxwood, euonymous, hydrangeas and many other plants.
Q. I have an evergreen clematis that flowers early. Now that it has finished blooming what do I do? It has put out lots of new growth. T., Email
A. Glad you were able to enjoy the fragrant white blossoms of the clematis armandii. This clematis will stay tidy if you prune back about a third of the new growth once the vine stops flowering. Always clip any dead vines that are brown with no new foliage. That clematis is very sensitive to salts in the soil so be careful not to over fertilize. A slow release plant food or compost mulch is best. Cold winds can also cause the evergreen leaves to turn brown. Grow the evergreen clematis in a protected location.
Q. My first try at growing clematis failed. The vine was growing great then just turned limp and died like it had dried out – but the soil was still moist. I would like to know if there are some easy to grow clematis because I really love the beautiful flowers. P., Email
A. Look for the easy-to-grow clematis named ‘Nelly Moser’ with huge lavender and pink striped blooms or the deep purple clematis ‘jackamani’ if you want dependable summer color. Many clematis varieties do well in our climate despite the heart break of clematis wilt disease – the likely cause of your clematis loss.
When planting clematis make a huge hole – three feet wide by two feet deep. Remove rocks and loosen the soil. Mix in compost with the back fill soil, but do not place compost in the bottom of the planting hole or this will act as a sponge to collect winter moisture. Plant the crown or base of the clematis a few inches deeper than it was growing.
Keep the roots cool with a 2-inch layer of mulch on top of the roots but do not let the mulch touch the stems of the clematis. The clematis vine likes to grow with its top in the sun and its feet in the shade. Do not place a stone or any heat absorbing material like gravel near the roots. Now don’t be surprised if your missing clematis pops up fresh this spring or even a few years from now. Clematis that disappear from wilt disease have been known to reappear and pull a Lazarus.
Q. I won a primrose plant at one of your talks three years ago. That primrose has grown huge and flowers for months in the spring. Do you think I should divide it? It is almost three times as wide as when you gave it to me. Thank you. K.W., Renton
A. Congrats on your green thumb. Primroses love cool moist soil so it would be better to dig up and divide your primrose plant in the spring as it finishes up flowering, or in the fall once cool weather returns. Dig up the entire clump and use a knife or sharp trowel to cut into the clump, separating it into three or four smaller sections. Replant each section into moist soil that has been loosened. Throw away any part of the center of the clump that looks dry or dead. You can also pot up the divided clumps and enjoy in pots or share with others.
Marianne Binetti has a degree in horticulture from Washington State University and is the author of several books. Reach her at binettigarden.com.
10 a.m., June 3: Learn more about growing clematis, hydrangeas and other summer bloomers, Windmill Gardens, 16009 60th St. E., Sumner. Register at 253-863-5843 or windmillgardenscom. $5 fee.