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Fertilizer, Pruning, Geraniums, Bentgrass & PNWFS

What plant food to use; pruning dead branches from holly; geraniums that may be virused; and bentgrass problems plus an update on the flower show scene!
by Art Drysdale
by Art Drysdale


Art Drysdale, a life-long resident of Toronto and a horticulturist well known all across Canada, is now a resident of Parksville, British Columbia on Vancouver Island, just north of Nanaimo. He has reno-vated an old home and has a new garden there. His radio gardening vignettes are heard in south-western Ontario over radio station Easy 101 FM out of Tillsonburg at 2 PM weekdays.

Art also has his own website at

June 14, 2009

Above, our tree peony blooms between two different variegated cultivars of holly, and in the back, one green-leaved cultivar with some berries from the previous season; a typical shot of balcon geraniums growing in Oberamergau Germany--these too are very subject to viruses; and a shot of bentgrass infesting a lawn. Below, two other recent shots from our garden here, first the lawn alongside the perennial border which surrounds our large pond showing ‘Lee’s Best Purple’ Rhododendron, lupines and in the distance some wallflowers; and finally our geyser in the large pond with the sun on it.
Author photos.

First, a couple of questions that were directed to Donna Dawson. The first from George Rhiner, of unknown location, asked a simple question: “Hi--question what is the best plant food for flower and vegetable you can recommend. Thanks and regards.”

That is a common question, and one to which there is no basic answer. I always tell folks any fertilizer is better than none, especially if your soil is pure sand as is the case in our garden now and one I had a way back, up until 1986 in Toronto.

I also tell folks that if you already have a fertilizer sitting around, and something needs nutrition, then why not use what you have. There should be some exceptions to that. I would not recommend using a strong lawn fertilizer (something with a double-digit first number--Nitrogen) for flowers. That likewise applies to vegetables such as tomatoes, beans, cucumbers, okra, peas, even carrots and beets where you are dependent on either the flowers and or fruits. However, that same lawn fertilizer would be fine for spinach, lettuce, rhubarb etc. where foliage is what you want in the harvest.

The first discussion currently is usually whether to use an organic or chemical fertilizer. It seems these days that the organic people knock chemical fertilizer automatically. Not fair! Did you know that plants definitely cannot tell the difference between a specific nutrition that comes from an organic source vs. one that comes from a chemical source? If we had not had, or did not have chemical fertilizers, we would not have been able to feed the world for the last many decades. Now, organic fertilizers are better for the soil than chemical ones, but that can be overcome in a couple of ways, including the addition of home compost to the soil at least once per year. Also, it is possible to grow most ‘crops’ well simply by putting as poor a soil as we have in our garden (we live on a sand bar!) on top of concrete, or rock, and adding chemical fertilizer. The addition of compost is a nice luxury, but it washes down to the depths (if not on rocks or concrete) in a matter of a year or two. All additives to a sandy soil wash down ever so fast. Clay soils are different, as their fine particles retain nutrients much longer.

The second discussion when considering what type of plant food is whether to use a granular, dry fertilizer, or a water soluble powder. As many of you will know from reading or hearing me on this topic for over four decades, I lean to liquid fertilization because there is a faster overall result--at least a percentage of the nutrients are absorbed by the foliage on which they are sprayed, and the balance goes into the soil for the roots to pick up. If it is a matter of price, granular, dry fertilizers almost always are more economical than liquids or soluble powders.

Generally high middle number soluble fertilizers (i.e. 15-30-15 or 8-16-8) are best for flowers and non-leafy vegetables, and high Nitrogen analyses (i.e. 18-3-3 or 18-2-5) are better for plants where you want high leaf production (i.e. lawns, lettuce etc.). And, it is always good to have a general purpose soluble fertilizer around, such as 10-10-10 or 20-20-20. Now, whatever you do, do NOT fall into the trap that so many people do; believing that only the two later analyses are “balanced.” All fertilizers that have any percentage of fertilizer of the three primary ingredients (the three numbers on the container) are balanced--by definition. Those people who write and say the opposite are simply wrong!

Let’s turn to another question sent to Donna, this one from Sandra Macneil, also of unknown location: “My holly got hit with frost but continue to grow nicely at the bottom. My question is do I cut the frost part off which of course is brown leaves or leave it be? Thank you.”

A quick answer: Yes! Before you cut anything though, make sure it is dead: i.e. the stems are brown and dry if you scratch their surface. Then cut the dead portions off. I would be interested in knowing where you live with regard to the hardiness of hollies. And, I presume you are writing about the hardiest ones, the so-called “blue hollies”.

This next one comes from Tillsonburg Ontario, a small town in Ontario’s tobacco growing area that I know fairly well because I have had my 90 second radio gardening vignettes running there for over a decade on John Lamers’ EASY101. Here is the question: “Hello Art! My wife and I are experiencing something strange with our geraniums this year. The plants look wonderfully healthy and they begin to produce stems with the blooms, and then stop. The stem just below the buds starts to turn yellow and then dries up. The first time it happened she cut back all the stems and the second set have appeared and the same thing is happening. Any idea??”

Now that is an unusual and disappointing problem. My first guess would be that the plants have a virus, which is initially just claiming the flowers as they develop. Two decades ago or more in southern Ontario, geranium growers started getting reports, mainly about the common Zonal Geraniums, that while they bloomed well in the spring, by the time the heat of July rolled around the plants all stopped blooming. And, they did not re-commence blooming until the cooler weather returned in mid or even late September.

The virus was diagnosed and growers did one of two regimens to eliminate the problem. One was to grow the plants in a sterile environment where anyone entering the greenhouses would walk through a sterilizing solution to eliminate the transfer of the virus from nearby soil. In addition, all insects were excluded through screening. The other method was to grow the plants through a number of successive cuttings; i.e. after a cutting rooted and started growing, say to 10 cm (4”) of growth, a new cutting would be taken from the top of each young plant and the old rooted bases would be put in the garbage. This done two or three times seemed to eliminate enough of the virus so that it did not impact the plants in their first year. The reason this worked is that the virus is usually centred at the base of the stem, and not up at the top of the actively growing cutting.

It sounds to me that you may have that virus or one similar to it. If you bought your geraniums as young plants at a garden centre, you should advise them--they may well have had similar reports from other customers, and may re-place the stock. If you grew the plants from cuttings you took yourself (or someone else did) using old ‘mother’ plants from the previous year, then you very well could have a virus similar to the one I described. And, the only answer, for another year, is the two- or three-cutting regimen I described.

Sorry not to be able to help more.

The final question this week came in just on Friday, from Diane Church of Hamilton Ontario: “I am getting in my lawn a type of grass that is growing in patches and it looks like something has laid on it, and flatted it down; it seems to be bent over and I don’t think that the lawn mower is cutting much off of the top. The grass in these patches seems to be a lighter colour of green. I looked up bent grass but I don’t think that is what I have. I have also sprayed it with Ortho weed control that does not kill the grass but nothing seems to happen to it. My lawn is very thick and is fertilized five times through the year from a lawn company. Do you have any idea as to what this would be? Thanks.”

Well, Diane, I think you may be wrong! I do think it is one or another type of bentgrass. Now, it is often possible to kill bentgrass with several “stiff” applications of a combined weed control product such as Killex or Lawn WeedOut. It often dies. However, since you are in Hamilton, theoretically you cannot use such “cosmetic pesticide products” due to the new Ontario law. You’ll have to wait until the Conservatives are elected (one potential leader is promising a repeal of the law)!

The only other answer is to hand remove the plants!

Finally this week there is good news on the flower show front. Duane Kelly, owner of both the Northwest Flower & Garden Show in Seattle annually in February, and the San Francisco Flower & Garden Show annually in March, has announced that he has accepted an offer to purchase the Seattle show, and expects the deal to close around the end of this month. This deal follows the sale of the San Francisco show that was finalized late last month to a new group known as San Francisco Flower Show LLC. If you wish to read some background on this just go to: . Many photos of the 2007 and 2008 Northwest Show are included there.

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