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Past Questions and Answers | November 2010



This month's questions concern:

Overwintering Pelargoniums
Overwintering Strawberries
Get Poinsettias To Turn Red
Pollinating Passion Fruit
Dripping Dieffenbachia
Split Oranges
High pH Of Soil
Which Bulbs Need To Be Overwintered
Are Rhododendrons And Oleander Related
Planting Runner Beans Every Year
Sheared Avocado Tree

Please scroll down to read the answers.


Question #1:  Overwintering Pelargoniums

Question:  In your January 2007 Issue, you discussed the overwintering of pelargoniums in grocery bags. I would like to try this. Should the bags be paper or plastic, or does it make a difference? As I have limited space, I wonder about the procedure of bringing them out in the spring. When would that have to be done, and under what conditions?

 Barbara Clinton, Anchorage, AK, USA

 

ANSWER:   Hi Barbara! There was a lot of information in that article, so it was probably easy to miss, but the bag should be paper. If you put them in plastic, they will simply rot. As for when and how to bring them back out in the spring, here is the information again.

Dig the geraniums up and carefully shake all the soil from their roots. Then hang the plants upside down in a cool 45-50°: F (7.2-10 C), dry place. An alternate method is to place 1 or 2 plants in a large paper sack. Once a month during winter, soak the roots of each plant in water for 1 to 2 hours. Most of the leaves will eventually fall off. (The paper sack method is much cleaner than the hanging method.)

When: In the spring, when all chance of frost has past

What To Do: Prune or cut back each plant. Remove all shriveled, dead material. Healthy, live stems will be firm and solid. After pruning, pot up in a container, or plant the Geraniums back out into your garden, and water in well.

For the entire answer: overwintering geraniums.

I hope this helps clarify everything for you!



Question #2:  Overwintering Strawberries

Question:  My grandchildren have been growing strawberries and tomatoes in pots in my garden, are we supposed to bring them indoors over the winter? We have never tried anything like this before.

 Helen Logan, Kilwinning, Ayrshire, Scotland

 

ANSWER:   Hi Helen! Well, since tomatoes are an annual, and they are supposed to die at the end of summer, you don't need to worry about trying to overwinter them. The Stawberries, however, are a different story.

There are two different things you can do to overwinter strawberries in containers.

1. If you have the space: dig a hole in the ground and sink the pot up to its rim, and fill in the soil around it. By doing this, you're giving the plant all the benefits of being in the ground for the winter, which strawberries that are planted out would have. Put some mulch around them, like straw, or compost, or even shredded newspaper to help keep them warm and not freezing.

In the spring you can lift the pot out again.

You can also help your strawberries by double-potting them. That's when you place your existing container inside a larger one and fill the gap in between the two with soil that will act like insulation.

2. If you don't have the space: you can over winter them in your garage, or if you have a garden shed, as long as they are in a cold spot that doesn't freeze. The ideal temperature would be between freezing and about 45°' F (7.2° C). If you choose to do this, just don't forget to give the plants a little water during the cold dry months.

Good luck!



Question #3:  Get Poinsettias To Turn Red

Question:  When do we put the pointsettia from last year in the dark, and for how long to turn the leaves red? Many thanks.

 Wendy Osborne, Sevenoaks, Kent, UK

 

ANSWER:   Hi Wendy! While this isn't hard, it does take some diligence on your part to do. Actually I have seen people that have their plants in just the correct place in the house, and they have red poinsettias (Euphorbia pulcherrima) for the holidays every year!

This is quite rare though, so let's go over this:

Poinsettias are photoperiodic, so they will need a certain amount of dark and light to get them to flower and have red bracts again.

They need 10 weeks of dark to flower in time for the holidays. So you can start this around mid to late October. I know we are in the first week of November, but you can still start this now.

To give it complete dark put your plant in a closet or somewhere that NO light whatsoever can reach it (including flipping on a light switch), for 14 hours a night.

If you put your plant in the closet every day at 6 pm you could pull it out at 8 am every morning.

Move them into bright light for a maximum of 10 hours day, and then back into the closet every night.

That's all there is to it! It's a lot of moving around, but it is fun to see the plant come back every year.




Question #4:  Pollinating Passion Fruit

Question:  Have you any tips on hand-pollinating passionfruit? I have had my vine for a few years and the other one for almost two. There are plenty of flowers but never any fruit. Can you help me with some tips thanks.

 Deow Owen, Invercargill, New Zealand

 

ANSWER:   Hi Deow! I don't know what kind of passion vines (Passiflora) you have, if they are Passiflora edulis Sims (purple passion fruit); P. edulis f. flavicarpa Deg. (yellow passion fruit); or P. quadrangularis L. (giant granadilla).

Without knowing, here are some essentials.

Pollination is vital for fruit production on passion vines, as you well know. Flowers of the purple passion vine normally set fruit when self-pollinated, but many yellow passion vines will not set fruit unless their flowers are dusted with pollen from a different vine that is genetically compatible.

Therefore, if you have 2 plants grown from cuttings taken from the same vine, they cannot pollinate each other. And, some vines from a group of seedlings can cross-pollinate, and others cannot. Unfortunately, this can only be learned by trial and error as the plants develop.

The giant granadilla also needs pollination to ensure fruit set. It requires mild temperatures for normal fruiting, and may bloom but set no fruit (or misshapen fruit), during the hottest part of the summer.

To hand-pollinate purple passionfruit, simply dust each pistil with pollen from stamens of another flower. You can do this by using a paint brush and moving from one flower to another, or you can break off the stamens and lightly dust the pisitls.

To hand-pollinate yellow passionfruit dust the flowers with pollen from a flower of a genetically different, but compatible vine.

To hand-pollinate Giant Granadilla, you need to hand-pollinate in the late morning, within 4 to 6 hours of the flower's opening.

Let me know how it goes, I would like to know if it worked out for you!



Question #5:  Dripping Dieffenbachia

Question:  I have a very nice Dieffenbachia. It's doing well but I don't know why the leaves drip from time to time. Can you please explain?

 Valerei, Brechin, Ontario, CA

 

ANSWER:   Hi Valerei! Well, this is nothing serious and can be fixed very easily. What you are experiencing is called Guttation.

Many house plants do this when there is too much soil moisture. The plant absorbs more water than it can use, and it secrets the excess out through its leaves. This is super common in Dieffenbachia.

The solution is simple; reduce your watering a bit so the plant doesn't absorb excessive amounts of liquid. You can also increase air circulation around the plant, and improve its light source.

With a little more light and air movement, the plant will use the water rather than secrete it through its leaves.



Question #6:  Split Oranges

Question:  Why do my oranges split open on the tree before they are ripe? Very frustrating with all the babying I give them. Thanks.

 Susan Brown, Taft, CA, USA

 

ANSWER:   Hi Susan! This is a bummer of a problem because, I'm sorry to say, there isn't a lot that can be done to help the problem. Here's why.

Citrus fruits, especially navel oranges, seem to split spontaneously, and the cause is not completely understood. It doesn't have anything to do with a living organism, such as an insect or a plant disease, but in many people's opinions, the cause is environmental or cultural.

It sounds as though you are giving the tree great care, so I can understand your frustation.

To further illustrate my point, here is a report from UC Davis. They did extensive studies on this, since citrus is such a vital crop to California and Florida:

Splitting is a long-standing problem in many areas where navel oranges are grown commercially. The number of fruit affected varies from one citrus growing area to another. In some years, the percentage of split fruit is high, in other years it's negligible. Usually, splitting only affects a small portion of the fruit on each tree.

Navel oranges usually split when green - from September through November. The split usually starts at the navel end, the weakest point of the rind. The split can be short and shallow or it can be long and deep, exposing the segments and juice vesicles.

Splits probably occur when water and sugar are transported from the roots to the ripening fruit, and the rind is unable to expand as quickly as the interior. Some citrus varieties, especially thin-skinned ones, are more likely to split than other varieties. Rinds that have been sunburned or otherwise damaged may be more apt to split.

Although the exact cause is unknown, fruit splitting is likely the result of stress to the tree. Splitting appears to be most closely related to extreme fluctuations in temperature, humidity, soil moisture, and possibly fertilizer levels. The disorder is probably caused by a combination of these factors, rather than by one factor by itself. For example, when high winds occur during hot weather, the tree becomes drought stressed and begins taking water from the fruit, causing it to soften. If the tree is then irrigated heavily, the dehydrated fruit swells, causing it to crack.

Young trees, or dwarf varieties with relatively small or shallow root systems may be more susceptible to fruit splitting. Trees grown in sandy or porous soils that do not retain moisture well may also have a higher risk.

Reasonable cultural practices to avoid extreme fluctuations in soil moisture and fertilization levels during the growing season may help to minimize fruit split. Irrigate trees regularly to provide constant soil moisture, especially during hot or windy weather. When hot winds are expected, irrigate before the winds begin. After the hot winds subside, irrigate lightly for a few days and then resume a normal irrigation schedule. Instead of one large application of quick release fertilizer each year, smaller monthly applications throughout the growing season (February through May) help keep nutrient levels constant. Timed-release fertilizers supply nutrients at an even rate over the growing season, but they are usually more expensive than other fertilizers.

Split oranges are edible, although they almost never ripen enough to use. They decay quickly and eventually drop from the tree. Remove and discard damaged fruit, as it is susceptible to invading organisms that may cause diseases such as Alternaria rot. Decaying fruit may also harbor fungi, bacteria, insects, or other unwanted pests.

While, all this information they provide is very interesting, the bottom line is, I have no solution for you. I'm sorry!



Question #7:  High pH Of Soil

Question:  I am in need of some help. I planted quite a few Magnolia grandiflora and they are edged off with English box. Also I planted an acer. It seems that the maple (acer) is not dead but dying slowly; Why? I took the PH of the soil and it came to the count of 10. It's very lime. Am I right? Also I put some compost in the soil because the soil was just bare sand with no body at all. Can you give some help? Also, which month from your calendar will correspond with our weather down under?

 Maria, Melbourne, Australia

 

ANSWER:   Hi Maria! Let's take this one at a time.

When a soil pH is at 10 (extremely high) you have a very alkaline soil. Normally people with acidic soils are told to add lime to raise the pH, so in your case, yes, your soil is very lime or alkaline. Too much so.

Adding compost alone, won't help your problem. It will help add texture to your soil, which it needs, but it wouldn't lower your pH, which is what you need to do.

In order to lower your pH, you will have to add sulfur to get it down to a neutral pH level, which would be around 7.

Now I don't know what kind of Maple (Acer) you have, there are many, but generally they prefer soil that is slightly acid and sandy, with some organic matter mixed in. You should add in some acid based plant fertilizer to help maintain the right balance.

If the area you are working with is too large, you should create a raised bed and mix in lot of peat, compost, and acid fertilizer to create a more optimal environment.

Magnolias, as a rule, also like acid soil (5.0), so you should try and follow the same soil improvements as I just mentioned.

As for the plant and monthly to do lists we offer in calender form, here is a guidline for you:

Australian Summer: December to February
Australian Autumn: March to May
Australian Winter: June to August
Australian Spring: September to November

Our calendars are based on Northern Hemisphere:

Summer: June to August
Autumn: September to November
Winter: December to February
Spring: March to May

So for your Summer, look at our calendars for June to August

For your Autumn, look at our calendars for September to November

For your Winter, look at our calendars for December to February

For your Spring, look at our calendars for March to May

I hope all this helps, let me know how you are doing!




Question #8:  Which Bulbs Need To Be Overwintered

Question:  How do I know which bulbs should be taken in for the winter?

 Deborah Chamberlain, White Pigeon, MI, USA

 

ANSWER:   Hi Deborah! This is a very good question, and I bet a lot of people have wondered the same thing at one time or another.

There are two major categories of bulbs. I am going to use the term "bulbs" very loosely here, since some "bulbs" are tubers, or rhiziomes, or corms, etc.).

The two major categories of bulbs are spring blooming and summer blooming. There are also several that bloom in the fall, but we'll ignore those for the moment.

Spring Bulbs:
Most spring bulbs do not need to be dug up once planted. They will go dormant naturally when exposed to cold weather, and won't be harmed.

In very warm climates, spring-flowering bulbs may need to be dug up and put into a cold location to force them into dormancy, like hyacinths, daffodils, tulips iris.

Since you live in a cold weather climate, you don't need to worry about this.

Summer bulbs:
Summer bulbs, however, are often more tender than spring bulbs and may require that they be dug up in the winter to prevent them from freezing.

Summer bulbs include tuberous begonia, dahlia, lilies, gladiolus, caladium, calla lily, and canna lily.

What To Do:

All of these plants should be dug after frost has browned the foliage, and then allow them to dry for about a week in a shady, well-ventilated site, such as a garage or tool shed. Remove any excess soil, and pack them in peat moss, vermiculite, or perlite.

Make sure the bulbs donít touch. That's in case one decays, the rot doesnít spread to its neighbors. Dusting them with a fungicide before storage will help prevent them from rotting.

Finding a good spot to store them can be difficult, but as a rule of thumb, all the summer flowering bulbs mentioned above should be stored near 40° F (4.4° C), except Caladium, which should be stored between 50 to 60° F (10 to 15.6° C).

Thanks for the great question!



Question #9:  Are Rhododendrons And Oleander Related

Question:  Could you please tell me if the Oleander is related to the Rhododendron with all the same problems such as if they are dug out, the ground is poisoned for a period of seven years? That is if they are related.

 Brian Pearson, Corfu, Greece

 

ANSWER:   Hi Brian! Oleander (Nerium) is in the Apocynaceae family, and Rhododendron (including Azalea) is in the Ericaceae family.

Just because they are not related doesn't mean that they are not both poisonous, because they are.

I personally have never heard of the soil being poisoned for 7 years, but I do know both plants are poisonous if eaten. If the debris is cleaned up, and some good fresh compost is added to the area, the soil should be just fine.

According to the University of North Carolina, all parts of azaleas and rhododendrons are among the most popular landscape plants, but ingesting their leaves or flowers can cause salivation, watering of eyes and nose, abdominal pain, loss of energy, depression, nausea and vomiting, diarrhea, weakness, difficult breathing, progressive paralysis of arms and legs, coma.

Oleanders when ingested in certain quatities, can cause harm - and possibly death.

I don't know if you have small children or pets that you are worried about eating the plants, but if you remove the entire plants, and their debris, and add in some new compost, you'll be just fine.



Question #10:  Planting Runner Beans Yearly

Question:  Not using the same plot every year for the same crop, does this apply to runner beans?

 Charles Hudson, London, UK

 

ANSWER:   Hi Charles! I can understand thinking that planting something like beans, peas, clover, or any thing in the legume family, every year might not be a problem. This is because legumes are often planted after heavy feeding vegetable crops like corn and squash because they fix nitrogen in the soil and help rejuvenate it.

That said, however, it is always a good idea to rotate your crops, to avoid build-up of pests and diseases that might result when the same crop is grown continuously.

In addition to avoiding problems, the soil is kept healthier with rotation because different crops add and remove different nutrients at different rates.

So, bottom line, since beans are subject to diseases that may carry over in the soil to reinfect the following bean crop, it would be a good idea for you to move them around if you can.

Good question!



Question #11:  Sheared Avocado Tree

Question:  My gardener misunderstood me and cut an avacacdo tree down to a 5 foot (1.5 m) stump! It was a tree started from a pit by one of my sons to I was really attatched it to! Questions: will be come back and if so, will the roots now spread more horizontally. It is planted about 10' (3 m) from my house. One person suggested putting Nutraplus or Formula 1 Spray on the stump cautioning me to use gloves so I don't burn" my hands! I am so unsure about all of this! Thanks for your help.

 Julia Mullen, Culver City, CA, USA

 

ANSWER:   Hi Julia! Well, I can understand your being upset over your tree. I had a neighbor recently reach over the fence and shear my avocado tree from the base to the top.

I now have a tree that has growth only on one side and it is very strange looking, plus a hazard now in winds, since it is lopsided and too heavy on one side. My tree, like yours, is now a problem but fixable, so take heart!

Your tree will come back. The branching structure of the tree however, is ruined forever. What you can do is train the new growth and selectively prune to start "rebuilding" your tree's structure. If you're not sure how to do this, ask a local certified arborist to come and consult you as your tree starts putting on new growth.

The roots won't spread any further since it's an established tree, so you don't have to worry about that.

As far as the Nutraplus or Formula 1 Spray, I have no idea why anyone would suggest using those products.

Hang in there and next time you hear a chainsaw starting up, check your property to make sure it isn't one of your trees someone is working on - I do!




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Keep Seedlings Moist

When you have just planted seeds, keep the soil moist until germination.

If the soil dries out, the seeds will die.

After germination, allow the soil to dry out a bit between waterings, but keep a close eye on the seedlings until they are well established.


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