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Past Questions and Answers | June 2007

This month's questions concern:

Rotate Tomatoes
Lipstick Plant Drops Flowers
Fertilizer Burn on Lawn
Dying Nandina
Spittle Bug
Poor Corn Pollination
Proper Watering Times
Roundup and Edible Crops
Unseasonable Cold Snap
Keeping Birds Away
Separating Overgrown Iris

Please scroll down to read the answers.

Question #1:  Rotate Tomatoes

Question:  I plant tomatoes every year in the same bed. Now last year I had a strange occurance - on top of the mulch there grew a white powdery-looking substance. Now I did get a crop of tomatoes, but there were a number that were not "pretty" - they'd have sizeable cracks develop by the stem, and some had scarring around the bottom of the tomato. Can I plant tomatoes there again this year? What can I do to rehabilitate the soil? Thank you for any assistance you can provide.

 Linda Muckey, Pennsylvania, USA


ANSWER:   Hi Linda! If I were you, I wouldn't plant tomatoes there again for 3 or 4 years. There is a strain on the soil when you grow the same crop year after year, and it also invites more disease and insect problems, many of which can overwinter in the soil.

Every year, try and rotate your crops, especially cabbage-family crops (cabbage, broccali, cauliflower, Brussels sprouts), nightshade-family crops (tomatoes, potatoes, peppers, and eggplants) and vine-family crops (cucumbers, squashes and melons).

Tomatoes and related vegetables, such as potatoes, peppers and eggplants, should not be planted on the same land more than once in three years. Ideally, any cover crop or crop preceding tomatoes should be members of the grass family. Corn, an excellent rotation crop with tomatoes, supplies large amounts of organic matter and does not promote the growth of disease organisms that attack tomatoes.

If you grow greens (spinach, chard, mustard, lettuce) or root crops, those don't seem to be as susceptible to disease and don't need to be rotated as often.

To improve your soil, you can put in crops like corn as I mentioned above, or crops like rye or clover between fall and spring crops so that the soil has been improved in time for spring planting. Also, every spring and fall, work a good amount of compost into the soil. This will really help soil texture and health.

If you want to see how I prep my soil, see last month's feature article: How To Start A Vegetable Garden

Good luck!

Question #2:  Lipstick Plant Drops Flowers

Question:  My Lipstick plant is a combination of two varieties (a small leafed variety and a larger leafed variety). I do not think I over water, and I fertilize about every 3 weeks with "Liquid Growth 2-12-12 with carbon." It is in a 12 inch (30 cm) self-watering pot (which I stopped bottom watering after course #4 of your Houseplant Tutorial!)

Originally I had it hanging with an eastern exposure, but because of the size of the plant (it is about 3 feet (.91 m) long) I had to move it to a northern exposure. I have not noticed any difference in the plant since the change of light exposure.

What my problem is and has been is that this plant develops flower pods (not as many as I would like) but what happens is often the pod does not fully develop, and it falls to the floor. There is no consistency in when the pod falls. Sometimes I do not see any red flowers developing, other times the flowers are just about to come out, and some blooms remain on the plant fully (as the picture shows). Any ideas as to what I am doing wrong? Any help would be appreciated.



ANSWER:   Hi Lorraine! That's great you're reading through the Houseplant Tutorial. Good work!

In regards to your Lipstick Plant (Aeschynanthus radicans (lobbianus)), There are couple of things I would do. Once a year, after your plant has finished flowering, pinch it back. This will help rejuvinate the plant and keep it flowering better and longer. Most tend to bloom heaviest in the fall, so in the early spring, pinch it back.

Also, I don't know how old your plant is, but mature plants can fail to bloom because they are in too large a container. Being pot bound triggers lipstick plants to bloom. As long as they have plenty of room, they tend to put their energy to new growth instead of blooming. If that is the case with you, you may need to give your plant a bit longer to fill into its pot.

During spring and summer, feed lipstick plants every two weeks. I would use a more balanced fertilizer like a 10-10-10, and then reduce fertilizing to once a month during the fall and winter months.

You might also want to check your humidity. When the humidity is too low, flowers will darken, almost to black, and fall off, since they are native to hot, moist places and need the high humidity to stay healthy. During the spring and summer, mist the foliage every day or two. In fall and winter, spray twice a week.

Lastly, water lipstick plants when they are approaching dryness. Avoid letting them dry out, but don't keep excessively moist, especially in the winter months. Always water with warm to tepid water.

Overall Lorraine, it looks like you are doing a really good job with your plant. It looks nice and healthy, but if you add the above to your routine, I think your plant will have many more flowers this fall.

Thanks for the question and sending in the picture!

Question #3:  Fertilizer Burn on Lawn

Question:  Hi, I spent 3 weeks digging down deep and removing all roots, weeds and stones. I then leveled the whole area, and I laid the long awaited turf in my garden. The garden looked really lovely and so green and there was no patches or dry areas. After about a week I decided to feed it with a liquid lawn feed but could not read what the directions said on the back of the food as it had been given to me and was old and faded so I poured the whole contents into a watering can and filled it up with water and scattered it around.

Now 2 weeks later everywhere that I scattered the fertilizer looks dead, and my lovely green lawn is ruined.I am so upset. I know its my own fault but havent got a clue what to do. I have been giving the problem areas a severe watering since I noticed the patches (2 days ago). Is there anything I can do to revive it or anything I can buy to make it green again. Thank you so much.

 Anita Maria McDevitt, London, UK


ANSWER:   Hi Anita! What a shame! My heart goes out to you, especailly after all the great prep work you did.

As of now, you are doing the correct thing. Leach out as much of the fertilizer as you can by heavily watering the dead areas. When you over fertilize like that, there is a huge salt build up in the soil, that's why the lawn gets burned out.

If after a few weeks of leaching the areas you don't see any new growth starting to fill back in, don't panic. You can buy a some replacement strips of sod and patch the areas. For some direction on that you can see an article I did a few months ago: Grow a Green, Lush Lawn - Part 2

In time, everything will come back and look terrific, so don't worry! Next time, as I'm sure I don't need to tell you, just toss anything that's so old you can't read the label! Hang in there!

Question #4:  Dying Nandina

Question:  I planted a Nandina domestica 'Firepower' last year and it was doing well til now. It is looking very unhealthy and maybe even dying, it is in a sunny spot near the house wall, what do you suggest? Thank you

 Trish Clifford, Horsham, West Sussex, England


ANSWER:   Hi Trish! This is a tough question, because Nandina are such resilient plants. There are only two things that come to mind. One is that Nandina don't like a lot of water. Allow them to dry out between waterings, so check to make sure your soil has good drainage, and try not to over water.

The second thing is that they are subject to chlorosis in alkaline soil. Now I realize in your part of the world, the soils tend to be more acidic, however, I don't know how old, or what material your house wall is made of.

Sometimes lime can leach out of house walls and concrete walks and can raise the alkalinity of the soil. Nandina like a mildly acidic to neutral soil (6.1 to 7.5). If for some reason there was a concrete walk there before, an acid loving plant won't be happy there. If that is the case, start fertilizing with an acid-based fertilizer and see if that doesn't help. Let me know how it goes!

Question #5:  Spittle Bug

Question:  Hi! I just noticed what I would call "foaming" on a few of my perennials (different varieties). The foaming is on just a few stems, not all of them, and it is right at the top growth. Any ideas what it is, if it is harmful, and if so, how to get rid of it?

 Deb Regan, Bloomington, MN, USA


ANSWER:   Hi Deb! Sounds like you have Spittle Bugs (Homoptera: Cercopidae). I used to get this on a juniper shrub every spring at my old house.

These are relatively harmless insects, and there are usually not enough spittle bugs on any one plant to cause much injury, however, extensive feeding by spittle bugs can cause yellowing or stunt plant growth.

They cover themselves in a white, frothy substance for protection from predators. When the spittle is removed, the small green larvae can be seen.

I used to wash them off with a strong stream of water, repeated a few times. The water will dislodge the bug, or wash the spit off of it. Once the "spit" is washed away from the bug, it dehydrates. No need, at all, to use chemicals on this bug.

Question #6:  Poor Corn Pollination

Question:  Last year my corn had only about half the cob covered with kernals. Tasted great, but could you tell me how to prevent this from happening to this year's crop?

 Randi Gulseth, Coos Bay, OR, USA


ANSWER:   Hi Randi! Sounds to me like you had some bad pollination going on. Whenever you see patchy spots on kernels, or ears that are not filled to the tip, that indicates inadequate pollination. Rain and wind can affect good pollination - wind can blow the pollen away very easily, and rain can stick the silks together so that some of them do not get pollinated.

In small home gardens you can hand pollinate to solve the problem. Strip the pollen from the tassles and sprinkle it on the silks, especially on plants on the outside edges of the plot.

The tassles are the male flowers located at the top of the stalk, and they drop their pollen onto the silks of the cobs. Each silk is connected to one kernal and so at least one pollen grain needs to land on each silk for germination to occur and thus the kernal to fill out properly.

If you have only a few plants, then because the tassels form pollen a couple of weeks earlier than the silks appear, and the tassels only bear pollen for two weeks or so, you will find that late cobs may not get sufficient pollen to fill the cobs, even when the weather is great. So it pays to have a lot of corn plants instead of only a few.

Also try planting your corn in blocks, instead of long rows.

Hope this helps.

Question #7:  Proper Watering Times

Question:  When is the best time of day to water a garden that has just been planted?

 David Seibert, Painesville, OH, USA


ANSWER:   Hi David! I am really glad you asked this question because it is a pet peeve of mine!!

Don't worry, I won't get on a soapbox here! That said however, the proper time to water anything, be it lawn, plants, or vegetable gardens, is first thing in the morning - there are very few exceptions to this.

The only exception to this is for people who live in the desert where night time temperatures stay high. Then those people can water lawns and plants in the evening without as much risk of disease infestation.

Everyone else needs to water in the morning so the plant material can dry off. Otherwise wet, plant foliage sits overnight and is literally ringing the dinner bell for all kinds of diseases and pests.

I'm glad you brought this up!

Question #8:  Roundup and Edible Crops

Question:  How soon after spraying Roundup, to kill wild grass, can I plant vegetables?

 Mary Lerma, Rep. of Ireland


ANSWER:   Hi Mary! I do believe every weed killer has its purpose. Sometimes a heavy duty chemical like Roundup is necessary to take care of very serious weed problems. That said, however, so many people use these very toxic chemcials and don't think twice about it.

There are so many other options to kill grass that are not as toxic. In the future you may want to try a product called BurnOut, a product sold by Plant Natural next time you have a grass problem. It is a non-selective, herbicide and can kill just grass just as good Roundup, but isn't made up from such toxic chemicals.

Back to your question, the waiting time for Roundup and edible crops is questionable.

With the exception of the Concentrated Roundup Weed and Grass Killer, none of the Roundup products have additional information on their labels about this.

For the three products that are ready to use, there is no reference to a longer waiting time for edible crops. There is no list distinguishing three-day crops from thirty-day crops. The only sentence in reference to planting after application is "Ornamentals and flowers may be planted or seeded 1 day after [the phrase �1 day after� appears in bold on all Roundup products] applying Roundup."

This omission is deceptive. The consumer is led to believe that it is safe to plant 1 day after Roundup is applied, when, in fact, there are many crops that should not be planted until 30 days have past. Among these are tomatoes, the staple of the home vegetable garden.

So Mary, I would wait 30 - 60 days to be sure, but keep in mind the only way to be 100% sure, is to not use Roundup around edible crops, or call the 800 number they have listed on the bottle and double check with them.

Good question!

Question #9:  Unseasonable Cold Snap

Question:  We've had really hot weather in the recent weeks, but suddenly, temperatures changed and the nights became frosty for two days. The tomato plant on my balcony reacted with wilted leaves (I couldn't bring it in as I was away on business). There are only two small leaves on top that still look ok. Is there anything I can do to help it survive?

 Michaela Pilz, Kreuzlingen, Switzerland


ANSWER:   Hi Michaela! What a bummer! You go away for business, and you come home to wilted plants.

Well, if it were me, I would give them one more chance before I tossed them out. Try replanting your tomatoes and see what happens. I don't know how much room you have, but if you can get a long container that is about 6 inches (15 cm) deep, I would strip off the wilted and dead looking leaves, but keep the ones that look OK on the plant, and replant your tomatoes on their sides.

For an example of this see last month's feature article: How To Start A Vegetable Garden

Tomatoes can be very tough, and by planting them on their side, it will help them develop more roots, and they will be stronger. Also, next time you leave, you may want to put a light shade cloth over them just in case.

Good luck, I hope they pull through.

Question #10:  Keeping Birds Away

Question:  I am currently growing some cauliflower and cabbages.I have a huge problem of birds eating of the leaves.How can I scare them away for good?

 Mrs. Mulla, Johannesburg, South Africa


ANSWER:   Hi Mrs. Mulla! I have used many different methods over the years to keep birds out of my crops. The two best are netting, and mylar strips, sometimes called bird repeller ribbon.

Netting works great for grapes, berries and some fruit crops. Mylar works great for fruit crops and vegetable crops.

Repeller ribbon is made from holographic mylar foil and is great for spot control for nuisance birds by producing a visual, audible and physical discomfort zone.

The light reflected from its holographic surface is menacing and scary to most pest birds. A light breeze will provide movement, and a metallic rattle, which keeps the nuisance animals at a distance.

Application is easy; with scissors, cut several pieces of ribbon 2 to 3 feet (.61-.91 m) long. Hang the length of ribbon where nuisance birds and animals will see and hear it. Fasten the strips at one end to the desired locations using whatever you have, string, twine, staples, etc., just make sure the length of ribbon can move freely with the wind.

In a garden, I would just put a few stakes around, and tie the ribbon to the top and let the rest hang down so it can blow in the wind.

Try it, I know you'll be as happy with it as I have been!

Question #11:  Separating Overgrown Iris

Question:  I have a bed of iris bulb down the length of my house. They are so overgrown they did not bloom this year. My question is how to thin them out? The tube like roots are all grown together. Help?

 Dawn Marshall, Kansas City, MO, USA


ANSWER:   Hi Dawn! From you question, I am going to assume you have Rhizomatous Iris as opposed to Iris that grow from true bulbs. You said the "tube like roots," that sounds rhizomatous to me, so I am going to answer that way.

Iris plants do spread by rhizomes, producing large, indefinitely expanding clumps that tend to decline and die out in the center unless periodically divided.

Dividing should be done after flowering is complete, but not later than mid-August.

Using a pitch fork, carefully dig around the iris plant, starting about a foot away from the outer most edge. Try not to pierce the rhizome with the fork. Work the fork around the bearded iris plant and gently lift the rhizomes out of the soil. Since bearded iris are grown at soil level, this is one of the easiest plants to lift.

Once you have the iris rhizomes lifted, shake off any loose soil. Rinse off any remaining soil with a garden hose. If you don't have space to do this in the garden, it is sometimes easier and neater to do it on a tarp. Rising off the soil will allow you to better see the rhizomes and roots, to inspect for damage. Once the rhizomes are cleaned, you can separate the individual rhizomes from one another. Don't break them apart, just loosen the already separate sections.

Once the rhizomes are clean, cut the foliage to about 6 inches (15 cm). Cutting the fan of leaves connected to a lifted iris rhizome makes the plant easier to work with when dividing and replanting and helps prevent water loss while the plant is becoming re-established. The fan does not need to be cut symmetrically. Some leaves may be damaged and will need to be cut shorter than 6 inches (15 cm).

Once the iris rhizomes are clean, look for small to medium holes, like the one on the rhizome above left. These are telltale signs of borer damage. If your iris leaves have dark streaks in them, you probably have iris borers, so look closely. Also look for soft spots like the front section of the above right rhizome. This is another common iris problem called soft rot.

Using a sharp knife or pruners, remove any traces of either iris borer damage or soft rot and dispose of these segments of rhizome. Soft rot spreads easily, so disinfect your cutting tool with denatured alcohol between cuts, to prevent further contamination.

Now you are ready to divide the rhizomes. You will see natural places to make a split, such as where the rhizome has forked. Study the rhizome and make sure each section you have chosen will wind up being at least 3 inches (7.5 cm) long and will have healthy roots growing from it. Then go ahead and make a clean cut through the rhizome, using the same sharp, disinfected knife or pruner.

The final step is re-planting your bearded iris. Choose a full sun location and start by digging a shallow hole that will be wide enough to spread out the rhizome's roots. Make the hole about 2-3 inches (5-7.5 cm) deep, then create a mound in the center of the hole to just about soil level.

Soak the soil in the planting hole. Then take a rhizome division and place it in the center of the mound making sure the newest leaves face the direction in which you want the plant to grow. Spread the roots around and down the mound. Cover the division with soil, being careful not to bury the rhizome with more than an 1 or 2 inches (2.5-5 cm) of soil. Remember, it will probably settle a bit lower and iris will rot and certainly won't bloom, if buried too deeply. Water well and do so weekly until you start to notice new growth.

Now you can enjoy your iris for another couple of years!

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