Phil’s Garden Tips and Tricks for May

May is the month that has inspired so many poets and song writers over hundreds of years, mostly because here in the Northern Hemisphere it is when many of the deciduous plants put out their foliage and many of the evergreens like Rhododendrons and Camellias put out their blooms. There are many perennials such as Peonies, Campanulas and Dianthus which begin blooming this month. Most of the bulbs of March and April are now finished and the warmer days have returned.

Those who are not so aware of the seasons might think that now is the best time to plant everything. But that is not true. It is the time to plant the vegetable garden, the lettuces, cucumbers and so on. However, the tomatoes and peppers should wait ’till June to really do well, that is when the real, regular warmer weather shows up.

The time to plant shrubs and trees is best done in the latter half of October through March when it is cooler and the rainy season descends. For now, if one plants shrubs and trees, they will need to be babied through this first summer or they will die because we are going into the dry season of our year. As a business we plant all year long because we have jobs all year long, but we have found that planting is the most successful if done in October through March.

The time to plant lawns by seed is April/May and September/October, but these seeds also need to be babied to get rooted and grow. July/August is often very hot and difficult (if not impossible), to get lawns to grow from seed, and the months of November through March are often too cold and wet and the seeds just rot. Often the best alternative is the more expensive but quicker method, laying down sod. Sod can be placed almost anytime of the year in our climate.

There is a cycle to the seasons and a best time for each gardening activity. May is the month for incredible growth of both weeds, (unwanted plants) and wanted plants! Therefore, it is the month to be diligent, but do not allow yourself to get overwhelmed. Simply make sure that the weeds which are preparing to set seed now, are the first to be pulled, and those who are still just thinking about it can be left for next week. Those plants which are going to seed should be put in the debris container. Never throw them on the ground! They will simply place your weed seeds there. The other weeds, which are just green growth and not going to seed, may be placed back in the bed behind some of your plants which you want, as long as the air is dry and they can shrivel. They will then just turn into mulch! If you allow yourself the luxury of NOT pulling the weeds going to seed and play a video game instead, you will be preparing for an even BIGGER onslaught of weeds next year.

Here is the list of Phil’s garden tasks for May…

    • Buy tender annuals and plant outside in your pots or flower beds if you are going to have blooming flowers such as Petunias and Impatiens. When a plant just lives through the growing season it is called an annual.
    • Begin moderate watering of lawns and beds. They begin drying out much more quickly this time of the year. Soak once every two weeks, more often if dry.
    • Fertilize lawn with a natural fertilizer (non-petrochemical).
    • Mow regularly. Set your lawn mower one more setting higher.
    • Thatch and renovate lawn only if you actually need it. If you use totally natural fertilizer, and not petroleum derivatives, you probably will never need to do this step as the earthworms will take care of your thatch and keep your ground, free-draining.
    • Weed.
    • If you have notches in your Rhodie and Azalea leaves you can Begin root weevil control. Safe alternatives are the use nematodes, DE (diatomaceous earth) or sticky traps on trunks of plants.
    • This is the time of the year to fertilize rhododendrons, azaleas and all shrubs that actually need it. If they look good and green and you mulch them they may not need any additional fertilizer. If you are into the neat and tidy look then it is the time to remove spent blossoms on shrubs like Rhodies, which have finished blooming.
    • Prune plants that need it after they flower this month, such as a Rhododendron, if it actually needs it.
    • Plant chrysanthemums now for perennial fall color.
    • Control aphids by washing foliage with soap suds, removing by hand, by pesticides, or by promoting natural predators, such as Ladybugs.
    • Tiny holes in foliage and the appearance of shiny, black beetles on cabbage, and potatoes indicate flea beetle attack or possibly cabbage butterflies. Treat the ground around the stems with DE, spray with BT (bacillus Thuringensis), soapy water; pick them off if you can find them, or all of the above.
    • Control slugs with bait, salt, or by smashing.
    • Begin liquid fertilizing of your new annuals. annuals. Natural organic fertilizer is best. Every two weeks is optimal right after you water.
    • Later in the month, plant these warm season vegetables: tomatoes, peppers, egg plants, snap and lima beans, Brussels sprouts, slicing and pickling cucumbers, dill, kale, pumpkins, summer and winter squash, onions, potatoes.
    • Spray fruit, nut, and shade trees for tent caterpillars, if present.

Be fearless, oh real estate/property owner! Tackle your land and bring it under control. Doing so can easily take the place of paying a gym to work out and it is right there at your finger-tips!

An Invasive Violet for Western Oregon

It is not uncommon for people to ask me about violets which seem to be taking over their yard.

Violets come up in planting beds and lawns in the early spring, with purplish-blue flowers and purple leaves in the sun but darker-green leaves in the shade. They can grow here in Western OR, even in gravely, dry soil where not much else will grow. They are not fragrant.

European Dog Violet
European Dog Violet

This is the European Dog Violet or technically, Viola riviniana ‘Purpurea Group’.  Sometimes V. riviniana plants are sold as Viola labradorica purpurea and sometimes even Viola hederacea, but I am told that those plants are not generally sold or even found growing in the NW.  Buyer beware!

V. riviniana can spread from its running fleshy roots which can plunge rather deeply, making this plant quite drought tolerant.

These plants can out compete smaller plants such as Mentha requenni  and can mar the look of a stand of slightly taller plants such as Ophiopogon p. ‘nigrescens’.  However bigger plants can comingle with no problems.  For instance, the currently invasive common exotic ivy, Hedera helix, can easily quash this violet but then who wants a groundcover of ivy?

V. riviniana can spread easily by seed as they shoot their seeds explosively, up to 8’ away when they are brown and ripe. Therefore, once established, they can become very numerous. On top of that fact, the seeds may stay viable for up to 5 years in the ground.

Some suggested methods of removal are:

  • Covering a densely growing area, where they are to be removed, with cardboard and 2” of bark mulch. Anything that dares to come up from far flung seeds, immediately remove with your handy Hori-Hori! This may take more than one year.
  • Hori Hori
    Phil’s trusty Hori-Hori

    I personally have removed all of my V. riviniana with only a hoe over the past 15 years. If I see one riding piggy back in the potting soil around a plant from a nursery, I immediately dispose of that violet in the garbage, not the compost pile! I wait to plant it in the ground, watching the potted plant and digging out any other unwanted Violets over the course of a year. I have seen several come up around a piggy-backed plant from a nursery!

  • There was a location in my garden, after the 10th year, where violets repeatedly came up from seed or old roots around the base of my largest old Azalea. Ultimately, I crawled on my hands and knees and surgically removed them with my Hori-Hori. They have not returned since.

Plants from the Genus Viola that you may want to cultivate in Western Oregon.   

viola sempervirens
Viola Sempervirens

We have some lovely native violets here in the Pacific NW, but many are robust growing as well. Try them where they will not cover smaller plants and you will be fine. You may find different species on-line. I have grown (and particularly like) a yellow one that is local and evergreen, Viola sempervirens. It is cheery in the spring. It spreads by stolons as well as seeds.

There are plenty of other lovely exotic violets that are not invasive. These Violas include the plants which we commonly call Violas and Pansies  in the nurseries. They have been bred to have large blooms and are available in many colors.

From what I have read, the most fragrant form of this plant is Viola odorata ‘Rosea’,  which is a bright pink form.

Final thoughts:

Clearing a property of Viola riviniana is not a task for the faint of heart.  It requires persistence and boldness and a ready willingness to dig in the rainy season, because that is when it is easiest to pull/dig out of the ground.  In the dry season of summer, it can be almost impossible to extract this Viola from the concrete-like dry ground. Your Hori-Hori is your best friend if you would like to rid yourself of these invasive plants.