The Yellow Farmhouse Garden

May 30, 2019

Epsom salts for better roses

In order to grow  and flourish all plants, including roses, require basically the same nutrients. One is carbon which is supplied to the plant by carbon dioxide in the air. Another, even though we may not think of it as a nutrient, is water.

In the soil, there are three primary nutrients that plants use in large quantities: nitrogen (N), phosphorus (P) and potassium (K). Together the primary nutrients are known as NPK. Good garden soil usually contains much of the required NPK . But sometimes soil is low in one or more of the primary nutrients so we supplement it with either organic or conventional fertilizers.

Secondary nutrients are need but in far less concentrations. They include calcium, magnesium and sulfur.

A long time ago rose growers noticed, even though roses were growing in very fertile soil, sometimes their blossoms still weren’t as nice as roses in other gardens. After much trial and error they found by adding Epsom salts, roses blooms would be noticeably improved. The missing ingredient was magnesium supplied by magnesium sulfate, more commonly known as Epsom salts.

The same Epsom salts you use in your bathwater can be used for your roses.


There are other sources of magnesium but some of them like dolomitic limestone can raise the soil pH. That would cause problems if your soil pH was already on the high side.

Add Epsom salts at the beginning of the growing season. For each mature rose bush apply a half cup of Epsom salts to the soil around the bush. You can do this either in dry form and water it in or dissolve it in water and apply as a solution. Do this every year to replace any magnesium used by the plant or leached out of the soil.



May 23, 2019

Purple deadnettle in the garden

As I was going through my seed potatoes a I remembered something I heard long ago. It was the concept of potatoes and their companion plants or what scientists call positive allelopathy. The basic idea is that some plants grow better in the presence of other kinds of plants.

We hear more about the opposite type of allelopathy, where plants secrete chemical compounds into the soil to inhibit the growth of other plants. The most well known example of a negative allelopathic plant is probably black walnut trees. Anyone with a small yard with a black walnut growing in it can tell you it is impossible to grow certain types of plants in the root zone of the tree.

Purple deadnettle (Lamium) is a common weed in many gardens. This is the time of year when it is most noticeable with its purple flowers and almost magenta colored upper leaves. It is thought by a lot of gardeners to have positive allelopathic effects, particularly on potatoes. A few deadnettle plants growing among potato plants is supposed to enhance growth and improve flavor as well as repel potato beetles.

Purple dead nettle has distinctive purple upper leaves and flowers.

Purple dead nettle has distinctive purple upper leaves and flowers.

Farmers don’t like purple deadnettle because it is a winter annual, a plant that germinates in the fall and flowers in the spring. But the biggest drawback of deadnettle (and a few other wild plants) is that it can harbor soybean cyst nematodes (SCN) a very severe malady of soybeans that can drastically reduce crop yields. Farmers are not willing to take a chance on their crop by letting deadnettles grow in their fields.

Gardeners on the other hand, rarely grow soybeans so a little bit of deadcnettle here and there is no problem.  Since SCN  is species specific, meaning other crops can’t be infected, you probably wouldn’t find SCN in a garden anyway.

The relatively short purple deadnettle can grow quite nicely under the partial shade of other plants like potatoes. They supposedly don’t steal nutrients from the soil that potatoes need. That sounds like  pretty good qualities to have in a companion plant.

I’ve never tried this in my own garden because I don’t have any purple deadnettle. I certainly would never introduce Lamium to my property because it can overrun an area fairly quickly. The seeds are viable for years so once you get deaednettle, you’ll always have it.


May 16, 2019

Ornamental pear trees may become invasive in the future

Ornamental Bradford pear trees are in full flower right now. They must be everyone’s favorite tree, or you would think so because everywhere there’s a housing development there’s at least one Bradford pear tree planted in front of every house. Even municipalities and businesses are planting them.

They do have a certain charm and they’re quite eye-catching when they’re in full bloom. But there’s so many of them now that they’re beginning to just become part of the background visual-noise instead of  being an accent in the landscape.

Landscapers plant Bradfords because of their flowers, shape and moderate size, and even though they are an introduced species, they are believed to be non-invasive by many. That has been the case in Michigan until recently. There’s evidence that these trees have become tired of being well-behaved and have decided to cut loose from their suburban lawns. This was pointed out to me a couple of years ago by a local, well-respected naturalist. To drive home her point she said all you had to do was look at the number of wild Bradford pears growing all along the highways.

Well, I drove the entire length of I -275 this week and was surprised how many out of place Bradford pears there were. They weren’t overcrowding any one area but there were plenty of single trees and small clusters of them. When you’re looking for them you begin to see them everywhere.

Even though this tree was covered with flowers, no bees were around. Bees seem t prefer other kinds of flowers if given the choice.


These more boisterous, escaped trees are claiming some area for themselves and have the potential to push out the native plants. The conventional wisdom that they are sterile and unable to reproduce may be true but something is going on. It brings to mind what Jeff Goldblum’s character Ian Malcolm said in the movie Jurassic Park, “Life uh, finds a way”.

In some other states Bradford pears are already a big enough problem that they have been place on those states invasive species list and are no longer recommended for planting.

To be fair, Bradford pears may never become a problem for us. I remember early in my career when, for a short time, some people worried smoke trees might escape and become invasive. Some trees did take root out of place here and there but the smoke tree invasion never materialized.

Maybe it’s time to think about developing a replacement for the Bradford pear if for no other reason than to add more variety to the suburban landscape.


May 3, 2019

Monitor soil temperatures often this spring

Soil temperatures have been cool enough during April that it has slowed down plant growth. My winter rye cover crop looks to be a week behind last year at this date and last year was later than normal as well. So that means we’re really behind. The apple tree buds have finally, slowly opened.

This may be the year to monitor soil temperatures more closely than usual if this cooling trend continues.

Some vegetable crop seeds can be sown into cold soil and do quite well under those conditions while others will not germinate or grow at all. There are certain minimum temperatures that seeds need in order to germinate. Seeds languishing in cold soil will be damaged or more likely, rot in place before they sprout.

For example, at 35 F you can expect spinach, onions, parsnips and lettuce to germinate. We’re well past that point by now.


Although not as durable, a kitchen thermometer makes an adequate replacement for a soil thermometer

Beets, cabbage, cauliflower, swiss chard, radishes, turnips, peas, and broccoli will all germinate at 40 F. Even though they are not technically seeds, seed potatoes will begin to grow at that temperature too.

Sweet corn requires the soil temperature to be at least 50 F. If they are pinched for time, some farmers will plant corn at lower soil temperatures but they always use seeds treated with fungicide to keep them from rotting in the soil.

A minimum soil temperature of 60 F is needed for warm weather crops like beans, cucumbers,melons,pumpkins and squash seeds to sprout.

Keep in mind that these are minimum required temperatures. Optimum germination temperatures may be five, ten or even twenty degrees higher in some cases.

You may have noticed that I didn’t include many common vegetables like peppers or tomatoes in these lists. That’s because in our growing area, those plants are generally grown as started transplants, not from seeds planted directly into the ground.


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