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All Past Questions and Answers Library   |   June 2009

This month's questions concern:

How To Get Rid Of Onion Maggots
Need A Filler For Containers
How Much Sun Can Caladium Tolerate
Make Your Own Topsy Turvy Tomato Bucket
Proper Houseplant Soil
Get Rid Of Pear Leaf Fungus

Please scroll down to read the answers.

Question #1:  How To Get Rid Of Onion Maggots

Question:  How do I get rid of onion maggots from my garden? I have rotated the crop to different areas, and tried wood ashes but nothing seems to work. I live in Manitoba in a zone 2-3. Any help would be greatly appreciated as I lost half of my onion crop last year.

 Gaylene Mushumanski , Manitoba, Canada


ANSWER:  Hi Gaylene! Bummer, onion maggots are tough to rid of. It can be done, but it will take some effort.

You have done everything right so far, but let's add a few more things into the mix.

Onion maggots, for those that don't have them are serious pests. The maggots burrow into developing onions and a single maggot can kill over a dozen seedlings during it's development. They can have two to three generations per year so they are a constant threat.

First thing to do is get rid of as many maggots that are still in the soil as possible.

1. If possible, (I don't know large your area is) remove the infected soil from the sites you have planted onions and had problems in the past. Replace it with clean compost. Then go to step 4 below.

If you can't remove the soil because the area is too large, then:

2. Drench the soil with this mixture:

3 hot green peppers (fresh or canned)
3 medium cloves garlic
1 small onion
1 tablespoon (15 ml) dishwashing soap
3 cups (720 ml) water

Puree peppers, garlic, onion in a blender. Pour the mixture into a jar and add the dishwashing soap and water. Let stand 24 hours. Strain out the solids and pour the liquid into a bottle and drench your soil.

3. Next get some insect parasitic nematodes that control maggots at your garden center and apply them to the soil as directed on the package.

You've now done about what you can to clean to soil of the maggots, the next step is to keep them out.

4. Cover seedlings with Floating Row Covers to keep the female flies from laying more eggs and starting the whole process over again.

You can also sprinkle your soil liberally with ground cayenne pepper, ginger, dill, or chili powder to repel the females.

5. Lastly, at the end of the season, make sure you get all onions, dead or alive out of the ground. You don't want to give the hibernating maggots a winter food supply.

That's about all you can do if you want to grow onions in the ground. You can always try growing them in containers with fresh soil as last resort.

The only thing I would be wary of was using too many wood ashes. Those are so hard on the soil and they can do more damage than good to your soil pH.

Hope this helps and good luck!

Question #2:  Need A Filler For Containers

Question:  I have two large pots in which I hope to grow Bizzy Lizzies, but it would take a lot of compost to fill them both. Would it be possible to fill them with something like gravel three quarters way up first and then the compost on top? I believe these plants are just surface plants and only need a certain amount of compost to grow in. Would the compost fall through the gravel in time? Also when I need to lift out the spent plants later next year, would it be necessary to dis-infect the gravel first before adding new compost for the next lot of plants? If so what do I use?.

 Marie Twomey, Cork, Ireland


ANSWER:  Hi Marie! Bizzy Lizzies (Impatiens walleriana) are indeed quite shallow-rooted plants and don't need huge amounts of soil to grow in - they need about 8 to 10 inches (20 to 25 cm) deep.

You could use gravel, but it is so heavy if you want to move your pots at some time. What I would do would be to recycle some of those styrofoam packing peanuts. If you don't have any your local post office or mailing center will.

1. Fill your pots with those and leave enough room for your compost and plants.

2. Take some landscape fabric and put it over the styrofoam. The fabric will keep the soil from falling into the cracks of the styrofoam peanuts.

3. Put your soil on top of fabric and plant your plants.

This way it will keep you pots lighter and accomplish the same thing.

If you need to replant, you don't have to disinfect anything, unless you see a problem.

Lastly, if you do need the weight, because of high wind or something, then you can use the gravel as you suggested, then the fabric, soil and plants.

Take care, good to hear from you again.

Question #3:  How Much Sun Can Caladium Tolerate?

Question:  How much sun can caladium tolerate?

 Veronica Reed, Milbridge, ME, US


ANSWER:  Hi Veronica! This is a great question because I just finished a 2-part, in-depth article about Caladium on my blog.

You can read them here:

Grow Caladium Bulbs, Elephant's Ear Indoors - Part 1

Grow Caladium Bulbs, Elephant's Ear Outdoors - Part 2

Once you read both of those articles, you will know everything you need to grow outstanding caladium! Thanks for the question.

Question #4:  Make Your Own Topsy Turvy Tomato Bucket

Question:  I bought a topsy turvy tomato grower, followed the instructions, and my tomato plant looks like a piece of asparagus. Will it come back or should I get a new plant?

 Linda Nasser, Iron River, MI, US


ANSWER:  Hi Linda! I was just laughing with my sister about her topsy turvy tomato because hers isn't doing too well either!

I'll tell you the same thing I told her, make your own topsy turvy. There are several ways you can do it, here are two:

1. Use a 5 Gallon Plastic Bucket:

1. Take a 5-gallon bucket with a tight-fitting lid. You can buy these cheaply at any hardware or paint store. Make sure your bucket has a secure handle for hanging with a large amount of weight of the moist soil and plant.

2. Clean the bucket well with soapy water and rinse it thoroughly. Cut an approximate 2 inch (5 cm) diameter hole in the center of the lid and one in the bottom of the bucket. To make the holes, you can use a drill with a hole saw.

3. With the bucket standing upright and the lid off, you should cover the holes with a coffee filter, some cheesecloth, or even sphagnum moss will work if packed tight enough. Just make sure the soil won't fall out of either hole when you turn the bucket over. Then fill the bucket almost full with a lightweight potting mix. Tap it down to remove any air pockets. Cover the bucket with the lid.

4. Turn the bucket over and gently make a hole to insert your tomato plant. Pack in more cloth if you feel it will be needed, although that is not usually the case. Water your plant and let it establish itself and its roots for about 2 weeks or more.

5. Find a great sunny place to hang your tomato plant. Remember, dried tomato plants produce rippled and hard fruit, so make sure you check it for water regularly and fertilize it a couple of times.

2. Use A Hanging Basket:

Just get yourself a hanging basket, the kind that already has the lining in it.

Then fill it with soil.

Buy an indeterminate tomato (one that keeps growing); there a dozens of varieties, but yellow pear and cherry tomatoes seem to really go wild.

Plant your tomato, hang it up in an area that gets good sun, keep it watered and fertilize it a couple of times.

You'll have a healthier plant, way more more tomatoes, and a great sense of satisfaction because your plant is going to do much better than the commercial products that come in the mail.

My sister is going to buy another topsy turvy anyway, and I'll probably be giving her tomatoes off my plants that are covered with fruit, because she bought a topsy turvy last year too, and that one gave her all of 5 tomatoes!

I wonder what you'll do? Let me know sometime, I'd love to know!

Question #5:  Proper Houseplant Soil

Question:  You speak of the right soil for houseplants. When we buy from a reputable nursery aren't the plants already in the right soil mix? Please advise, thank you.

 Sandra Ramini, M'sex, London, UK


ANSWER:  Hi Sandra! This is a great question! The answer is, not always.

Many reputable nurseries buy from vendors and the houseplants are shipped in. Many houseplant growers that need to ship, often have the issue of shipping costs and so they will use a very lightweight soil mix to keep costs down.

The soil they use often times has a lot of peat moss in it, which is not super nutrient rich for the plant. It also holds water for a long time so they don't have to water as much while they take care of the plant before you buy it.

Even if the nursery where you buy your plants actually does grow them on site, often times the soil they use may be just OK. I have a local grower here and he uses the cheapest mix he can make to keep his costs down.

He makes up for poor soil by feeding the plants rather heavily to get good growth on them fast so he can move them out the door quickly.

I would say for the most part that the soil nurseries use is fine, but I don't count on it and I have replanted houseplants before when they have had too much peat or bark in their soil mix.

The best plan of action is exactly what you are doing. Be aware of the soil people are using, shop carefully, and if you see a problem ask about it, or take the plant home and repot it!

Question #6:  Get Rid Of Pear Leaf Fungus

Question:  I have attached a picture of a leaf from a pear tree in my garden which is infected (both this year and last year). I have been treating it with two different types of fungicide (recommended by a local garden centre) for the last two years, but the problem does not seem to be going away. If you have any advice, I would appreciate it.

 Michael Finlan, Watermael-Boitsfort, Belgium


ANSWER:  Hi Michael! Thank you for sending in a picture. That is always very helpful.

You are on the right track, you have a fungal problem. It looks like a pear leaf spot, rust, or other fungus. I have two questions for you:

1. Do you have any other trees around like apple, cedar or other fruit trees near by?

2. Do you see any galls (hard, brown swellings) on their branches or trunks?

If you do see galls, remove and destroy them, because they are producing the spores that infect the trees. Apples, pears, quince, cedar can all be affected.

This type of fungus can be hard to get rid of because the spores can be harbored in so many other areas like galls, leaves, twigs, etc.

You can:

1. Purchase a new tree that is resistant

2. Get rid of any galls, infected branches or leaves you see.

3. Start spraying weekly with Neem oil. This is an organic and safe to use spray and it kills viral, fungal, and bacterial problems - basically everything - it is really good.

4. Make sure in the fall you rake up and get rid of any fallen leaves to remove overwintering sites for the fungus.

You will have to keep at it, and you will need to get rid of all the sources of the spores before you will see improvement, so look around carefully.

I hope this helps, let me know, and have a great day!

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