In the previous post I talked about Rhododendron impeditum and how it had been damaged by lace bugs (at right). I talked about how the shrubs were now ugly, and that I would replace them.
Now, I know what is going on here, but in considering up the reasoning process one would go through to analyze this situation, two sideline topics came up. And those are the things I want to talk about today.
Yes, these shrubs are being attacked by lace bugs. One can look at the leaves and see the characteristic damage and also the residual ‘poo’ left by the insects. And at the appropriate time of the year, one can also actually SEE the bugs. So yes, these shrubs have lace bug infestation.
A prudent, savvy gardener would want to know WHY the infestation occurred? And if it’s not controllable (preferably organically), what would be a suitable replacement plant? And by suitable, we mean not ANOTHER rhodie, for might it not also be eaten by the same bugs given that the bugs are already here?
So, why are lace bugs damaging these 2 dwarf rhodies when they are barely touching the larger one (top of photo at right)? Is it the type of rhodie that is more resistant to lace bugs? Yes, that might be part of it. Not all members of the same plant family, genus, species behave the same as all it’s relatives.
You can see one question often leads to others on the way to finding a solution to a horticulture problem. A prudent, savvy gardeners will do a good bit of research, even if that is just asking for the advice of someone more experienced with the situation. So in writing this post, I decided to do the first thing that should be done in determining if a plant is in the right location. That is looking up the plant in some sort of horticulture database. You can use your Sunset Western Garden Book or another book you have on hand. I typed the shrub’s botanical name into Google. Always use the Latin botanical name.
One of the first returns was major plant grower, Monrovia. This almost immediately lead to my first sideline topic. Exposure. Warning: I’m not going to go into what went wrong with my rhodie. If you really want to know, ask me in a comment, and I’ll tell all!
When we speak about exposure we are referring to how much sunlight a plant needs. I do believe I have previously mentioned that a plant’s liking or preferring a particular exposure is in no way the same as being tolerant of a certain exposure. Think about it. You may be able to choke down canned peas, but you adore freshly shelled peas from the garden. Canned peas : tolerate. Fresh peas : like or prefer. See the difference?
A guiding principle in gardening these days is called right plant / right place. Part of putting a plant in the right place in a garden is respecting it’s culture needs. Exposure is one of the culture needs. Need. Wants and needs are different. A need means you actually can’t live without it. If you don’t get something you want, it won’t kill you. When we speak of culture needs, they are the things a plant needs to live.
So plants need certain exposures, which is similar or different to other plants. Monrovia’s listing said my shrub needs part sun. Do you know what is meant by part sun? Are you sure?
Some guides say part sun means 4–6 hours of direct sun. (A full day of sun is usually considered to be about 6–8 hours.) But they also say the same thing for part shade — 4–6 hours of direct sun. Some guides say part sun means the plant can take closer to 6 hours of direct sun while part shade prefers closer to 4 hours. Some guides say part shade means it won’t tolerate afternoon sun, while part sun WILL tolerate late afternoon exposure.
How do we know which is correct? Well, they are all correct at various times, in various places. Keep reading. :-)
When I started gardening in the Pacific Northwest, I was told the following: In the PNW, we distinguish partial sun vs partial shade according to the time of day because our latitude causes afternoon sunshine to be considerably more harsh and punishing than morning sunshine. Part shade means a plant likes to receive it’s 4–6 hours of sunshine in the morning, avoiding the harsh afternoon rays. Part sun means a plant can handle those harsh afternoon rays, and can be planted where it will receive it’s 4–6 hours of sunshine facing the west (or east or south).
This type of wisdom is known as local knowledge. It is information that very often is not written in textbooks and specific to the local region in which you garden. You may have even more quirky local knowledge of the various micro-climates in your own garden.
Local knowledge is the fine detail or circumstance that uniquely affects the subject at hand, at that time, in that place. It is usually rendered by someone with long-time experience in that local area. Local knowledge is the best knowledge about a lot of things, subjects and situations, but it is intensely true about gardening and horticulture. The same plant may both grow in Zone 8 here in the PNW, and also on the East Coast, but it may grow a bit differently, and it’s culture needs, other than cold hardiness, may vary a bit. This can be said for 2 areas designated as Zone 8, but with differing altitudes. And I can guarantee you’ll think Zone 8 in north-central Arizona is quite a different climate than it is here in Vancouver, WA.
All of this is why I always recommend when you are looking for information about plants, that you get local knowledge. Furthermore, I like to find at least 3 trusted sources that say more or less the same thing. To me here on the west side of the Cascades, local knowledge is a well-established horticulture resource who does their growing, breeding, gardening, designing, etc, also on the west side of the Cascades. I don’t insist they only do their thing in Zone 8, but have experience with our culture situation in this region. Check out some of my trusted local resources.
So… if you live in a generic, mass-market area, you can take generic, mass-market advice. But come on, do YOU live in a generic, mass-market area? I am certain I have NEVER lived in such a place. :-) Unfortunately, most resources that are marketed to the country in general won’t give you information specific to your unique situation and location. Gardeners must be pro-active. Seek out local knowledge.
I also recommend utilizing independent garden centers rather than big-box stores, particularly if you are a novice. In general, I believe the independent guys are able to provide better local knowledge. Another great source of local knowledge is your local Extension and it’s branch of Master Gardeners. My local branch is Clark County WSU Master Gardeners. Do you know how to find yours?
I am not poo-pooing Monrovia. They have a great reputation, and I utilize their information all the time. I buy their plants! How can one not? :-) They may be mass-market, but their reputation gives them solid credibility in the market. Sun exposure is not the ONLY thing. This is why I recommend finding at least 3 trusted sources of information and making sure they overlap on the major points. For the finer points, go with the resources that is most local to you.
You will very often see a fairly wide variety in stated plant sizes from different plant growers / vendors. This is because the growers observe their own plants’ growth at facilities in variety of places. Refer to the first paragraph under Local Knowledge about how the same plant growing differently in Zone 8 on East and West Coasts, etc. This makes it very important for you to understand where your information is coming from.