Questions and Answers on Gardening
How to Test Soil For Magnesium Level
This question is in response to last month’s emailed gardening tip. You mentioned to make sure to do a soil test to see what your magnesium level is before adding any Epsom salt to outdoor plants. You said, “Without knowing your current magnesium levels, you shouldn’t apply Epsom salt at all to outdoor plants. Many areas have almost toxic proportions of magnesium present in the soil, and continually adding more will end up poisoning the plants and the soil.” That’s great, but how do I test for Magnesium levels?
Jim Trueman, UK
Hi Jim! Great question. Since most home “do-it-yourself” soil testing kits only test for pH, Nitrogen, Potassium, and Phosphorous, in order to find out your calcium and magnesium levels you’ll have to take a sample to a local soil testing lab. Every county has one, and the cost is usually around $10 (£5). It’s fast and very accurate.
Out Of Control Weeds
We have recently moved into our house, and the gardens are full of weeds. We have tried pulling them out, we have tried both chemical and organic weed killers, and tried solarization. Is there any other way. We just can’t seem to contain them.
Brad Martin, Lismore, NSW Australia
Hi Brad! I can hear and understand your frustration. Nothing is worse than a battle of the weeds. Unfortunately, the best advice I can give you is diligence, and try mixing up your techniques a bit more.
The problem with a lot of chemical weed killers is they do a great job of killing what’s there, but if you simply leave that area bare, and don’t do anything else, new weed and grass seeds can blow in and take root in the now clean and open area.
You also have to realize there are perennial and annual weeds, which means that at any time of the year, some kind of weed will be growing. The trick is to keep after it year-round and in a season or two, you will see a huge decrease in the problem as you kill each weed’s growing cycle and start to get the upper hand.
So what I would suggest is to pick a general weed killing method, I like solarization because it’s chemical free, but many people opt for RoundUp or another systemic weed killer.
Once you have killed everything back, come back in and put down some corn gluten, I mentioned this up on question # 6, see above if you didn’t read it.
Corn gluten is great because it will keep any new seeds from germinating. Keep in mind, it will keep all seeds from germinating, so if you are planning on starting a vegetable garden from seed, this will be a problem.
If that is the case, and you can’t put down a pre-emergent, put down a good layer of mulch, 2 to 3 inches (5.1 to 7.6 cm) to keep any new weeds smothered.
Hang in there, you have the right idea, and in time, your garden is going to look great.
What Is Heavy Soil
I want to start a water garden. I went and bought a Papyrus plant. I was told to repot plant and to use “heavy soil” and water plant fertilizer. Can you tell me what “heavy soil” is? And what type of fertilizer to use that can be used with fish in pond?
Ramona Diorec, Honolulu, HI, USA
Hi Ramona! Good question. Soils come in various “textures” meaning there sandy, loam, and clay soils, which some people can refer to as light, medium, and heavy soils.
Heavy soils (the same as a clay soil) are called that because they contain more clay, are sticky, and have little pore space, drain slowly and retain water and nutrients longer, which tend to make them more fertile than other soils, and are ideal for pond plants.
A medium soil (the same as a loam soil) which is considered the ideal garden soil (not for pond plants, but general gardening), because it has a nice balance of 3 particle types, clay, silt, and sand, giving it a combination of large and small pore spaces allowing it to have air for healthy root growth, and to drain well and lose nutrients at only a moderate rate.
Lastly, a light soil (the same as a sandy soil) contains particles that are fairly large and irregular, and have large pore spaces between the particles giving the soil lots of air, which drains very quickly losing nutrients and water. That’s why plants in sand need watering and feeding more often.
In your situation, you will want to use a heavy clay soil, and there are such soils packaged specifically for aquatic plants, so ask for that. In a pond situation, using the wrong type of soil can cause numerous problems, so start your plants out correctly with the right soil.
Now, just a few extra tips for you. One of the problems with ponds is that they can get a brown tinge to the water. This is because the soil has come out of the pot, which can happen in a high wind when the pot blows or falls over spilling soil into the water, or the soil washes out of the bottom of the pot. To avoid this problem here are a couple of things you can do:
1. Use a shorter wider pot (sometimes called a “pan”) because it is less likely to blow over than a taller pot, especially if it is a taller growing plant (like some Papyrus); and make sure that you add some medium sized stones on top of the soil to keep the soil in the pot. The stones will also add extra weight which will keep the pot from tipping over in the pond in the wind.
2. Line the pot with burlap, weed barrier mat or a few layers of damp newspaper. After the bottom of the pot is lined then add your soil and plant. This helps keep the soil from washing out the drainage holes into the pond. Once the plant is potted up, soak the entire pot in a bucket that is large enough to cover the top of the pot for about 24 hours. This will allow any loose soil to be washed off into the bucket of water and not in your pond.
3. When you are putting the plant in the pond make sure that you slowly lower the pot into the water rather than just plunge the pot into the water. By lowering the pot slowly this will keep the force of the water from washing the soil out of the pot and into the water.
The final part of your question was about fertilizer. There are many made especially for ponds, just ask for fertilizer for Pond Plants. It will be safe for all aquatic life, and it won’t turn water green from algae growth.
Leafminers on Tomatoes
I have 5 pots of “patio” tomotoes growing in large pots on my balcony. All 5 plants have tan “schrigely” marks on them, as you can see in the picture. Not all leaves have these marks. Also, the newest growth leaves on top of plants do not have these marks (yet??). Any suggestions as to the problem? Thanks.
Bob Coyne, FL, USA
Hi Bob! First of all, thank you for sending a picture with your question. It always is so helpful to be able to see exactly what you are talking about.
What you have are called Leafminers. They like to feed on bean, beet, cabbage, chard, lettuce, pepper, tomato, and other vegetables; also many ornamentals, especially chrysanthemum and nasturtium.
The larvae tunnel through the leaf tissue making hollowed-out, winding mines. They can kill seedlings, but the good news is that on older plants, such as your tomatoes, the larvae are more of a nuisance, and a cosmetic issue, than a serious problem.
There are a few things you can do:
1. Handpick and destroy mined leaves.
2. Remove any egg clusters you may see on the undersides of the leafs as soon as they are visible in the spring.
3. You can also spray neem oil. Read more about neem oil.