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Garden Questions of the Week
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Timely Gardening Information Customer service staff at Hole's regularly post up the most commonly asked questions. |
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There are black, nut-like clusters on my mayday. What are they and how do I cure them?
The Science Behind it: Your tree has likely been stricken with a serious plant disease called black knot of cherry. At the fruiting stage, the disease seems to billow out of the branch or trunk. The only solution is to prune out the affected branches well below the knot. Be sure to seal the pruned branches in a plastic garbage bag and to clean your prun-ing tools between cuts with a bleach or ethyl alcohol solution to prevent spreading this disease. It affects all members of the genus Prunus—cherry, mayday, plum, etc.
How should I clean my pruners after trimming black knot or fireblight off my trees?
Practical Answer: Cleaning your pruners between cuts is a good all-around practice. Two products work well: bleach (sodium hypochlorite) and ethyl alcohol (ethanol). Dip the pruners in the solution after each cut to avoid spreading disease. The Science Behind it: Bleach eats into metal, so don’t leave your pruners in the bleach solution for any length of time. After the job is done, apply a lightweight oil to the blades to prevent rust damage. Use a ten-percent bleach solution (one part household bleach to nine parts water) or a seventy-percent ethanol solution.
How do I determine how far apart to set my plants?
Practical Answer: Check your plant’s tag (or the seed packet, if you’re growing from seed) to find how big the mature plants will be. Use that as a guideline when transplanting. Give each plant enough space so that a mature plant’s leaves won’t overlap with the plant beside it. Tightly crowded plants won’t thrive and are more vulnerable to pests and disease.
What is transplant shock?
Practical Answer: Transplant shock is just a fancy term for stress. Many plants naturally suffer when they are moved, but with proper care they come through just fine. Symptoms of transplant shock include wilt-ing of foliage and stems, slow growth, and even foliage drop. For instance, weeping larch will often drop all its needles after trans-planting, but in a few weeks it should begin to regenerate new nee-dles and recover fully. The Science Behind it: When you move a tree from one location to another, you end up removing as much as 95 percent of its root system. It’s difficult to avoid this, because tree roots spread out a long distance from the trunk. Since roots are essential for absorbing moisture and nu-trients, a newly transplanted tree is severely stressed until it can regenerate those lost roots. Water is the key to survival for these trees. Keep the soil around the tree consistently moist (but not saturated) until it gets re-established.
If I plant my tomato plants in June, will I still get tomatoes this year?
Practical Answer: Yes, if the transplants are large. You should also shop for earlier varieties. The Science Behind it: A small seedling planted in June will not likely produce mature fruit before the first fall frost except in warm regions with a very long season.
Do containers need extra water?
Practical Answer: Yes. Containerized plants need more water than those grown in the garden. Larger containers can hold more moisture than small containers, but you’ll still need to water them almost every day. The Science Behind it: Yes, you should water containerized vegetables every day during hot, sunny weather. The same vegetables growing in the garden may need water only once a week. In the garden, water moves greater distances both down into the soil and horizontally. This provides your plants with a much greater moisture reserve. At the same time, in the garden the roots of your plants have a lot more room to spread. A plant in a container is essentially a captive in a closed environment. You have to provide it with everything it needs—and that includes plenty of water.
Do hanging baskets need extra water?
Practical Answer: On a hot day, if you water a hanging basket in the morning, it may be dry when you come home from work. The smaller the pot, the greater the problem. That’s why I tell people not to bother with hanging baskets smaller than 35 cm in diameter. One trick I like to use when my hanging basket accidentally becomes too dry and the soil has shrunk from the sides of the pot is to submerge the entire basket in a pail of water until the soil is fully soaked. The Science Behind it: Hanging baskets tend to be more exposed to the wind and sun, so they’re particularly vulnerable to evaporation. At the same time, they can’t draw any extra moisture from the surrounding area. Your plants are dependent on the moisture in the container which only you can provide. A hanging basket that is fully grown tends to shed overhead water. Therefore watering at the soil level is essential to prevent drying.
How often should I water my tree?
Practical Answer: Water a newly transplanted tree several times per week for the first few weeks, until the root system becomes established. You seldom need to water mature trees, except during periods of drought. It’s a good idea to water your trees during dry spells, to keep them lush, healthy, and less vulnerable to insects and diseases. The Science Behind it: A good rule is to provide 5 L of water per 30 cm of height or spread (whichever is greater) per week.
How do I control aphids? They’re on my leaf lettuce!
Practical Answer: Aphids are a problem in everyone’s garden at one time or another. Although they don’t cause huge amounts of damage to plants, aphids have a rather unfortunate habit of winding up in your salad! To control aphids, check your plants often, beginning early in the season. Aphids, it seems, explode in population overnight. Mild insecticides like insecticidal soap are effective if sprayed at the beginning of an outbreak. If you still end up with aphids, simply wash your lettuce thoroughly in the sink before putting it into the salad bowl. The Science Behind it: When you spot aphids, spray affected plants with insecticidal soap, making sure not to miss the undersides of the leaves. Insecticidal soap causes little harm to aphid predators like lacewings and ladybugs. You can also try to attract more ladybugs to your garden, since they prey on aphids. Ladybug lures are available at most garden centres.
My yard seems to have become instantly infested with aphids. Where did they all come from?
The Science Behind it: Aphids really do seem to come out of nowhere! Some aphid species lay eggs on tree trunks in the fall. These hatch once the weather warms in the spring. Other aphid species can literally “blow in,” riding the winds from the Gulf of Mexico. Aphids reproduce very rapidly, especially during warm, dry weather. They are parthenogenetic, meaning that the females don’t require males in order to produce offspring. During the summer, aphids give birth to live young, not eggs, making reproduction that much quicker. An aphid can actually be “pregnant” when it is born! There are many different species of aphids: green peach aphid, foxglove aphid, melon aphid, and honeysuckle aphid, to name just a few. However, they all respond comparably to the same treatment. Try diatomaceous earth or insecticidal soap if the infestation is light. If you need stronger controls, several other pesticides are effective, but always read the label and apply as recommended. Again, your best defence is a good offence: keep your garden as healthy as possible.
Why are my tomato leaves curling?
Practical Answer: Two things can cause this. If the new growth is excessively twisted or distorted, the plants may have been exposed to 2,4-D or similar volatile weed-killers. If all of the leaves are curling, chances are the soil has been too dry. Give the roots a good, thorough soaking, and the plants will likely not suffer any serious long-term damage. The Science Behind it: Tomatoes have the potential for curling locked in their genes. It is a recessive trait, while flat leaves are the dominant trait. Curling can appear naturally and is no cause for alarm if weed-killer or water are not the problem.
Should I use weed barrier on my shrubs?
Practical Answer: Weed barriers, properly installed and maintained, can reduce the amount of time you spend hunched over your shrub beds. The Science Behind it: Use caution. Weed barriers prevent many weeds from emerging, but they also intercept water and reduce the movement of oxygen into the soil. Some people also cover the barrier with a thick mulch, which further hinders the movement of water and oxygen. If you use a weed barrier, ensure that the roots get enough water, and keep mulching to a maximum of 3 cm.
Do tomatoes need bees for pollination?
The Science Behind it: No. Tomatoes are almost entirely self-pollinated. Each flower produces pollen that fertilizes its own stigma and produces a fruit. Wind encourages pollen shed and thus aids pollination. Many commercial greenhouses do use bumblebees or mechanical methods to assist pollination, however, because there is insufficient air movement in that environment.
Why won’t my daylily bloom?
Practical Answer: Daylilies need six hours of direct sunlight every day; otherwise they bloom a lot less. Your daylilies also won’t bloom in the first year if they were too small when transplanted. When shopping for daylilies, choose plants that have been overwintered in pots and grown on in the spring prior to sale.
How does powdery mildew spread?
The Science Behind it: The mildew typically begins as a very tiny spore that lands on your leaf. It remains dormant until it gets the moisture it needs for germination. Once the leaf gets moist and stays moist for about three hours (say, from overhead sprinkling or condensation on a cool, moist night), the mildew begins to develop. It rapidly spreads in white strands (hyphae) across the face of the leaf, dropping pegs (haustoria) into the leaf to anchor it and allow it to draw nutrients from your plant. At that point, it doesn’t need any more leaf-surface moisture to proliferate—it can get all it needs directly from within the leaves. Powdery mildew tends to attack plants that are already vulnerable for one reason or another. Anything that weakens the plant allows the mildew to penetrate the leaf surface more easily. For instance, plants that don’t get enough sunlight tend to have thinner leaves, making them more prone to infection. Plants deficient in nutrients (calcium in particular) have weaker leaf-cell walls and are also more vulnerable. Powdery mildew also often attacks plants stressed by drought.
Which perennials are vulnerable to cutworms?
The Science Behind it: Cutworms can attack the soft, young growth on nearly any perennial, but they rarely cause any long-term damage to them.
My yard seems to have become instantly infested with aphids. Where did they all come from?
The Science Behind it: Aphids really do seem to come out of nowhere! Some aphid species lay eggs on tree trunks in the fall. These hatch once the weather warms in the spring. Other aphid species can literally “blow in,” riding the winds from the Gulf of Mexico. Aphids reproduce very rapidly, especially during warm, dry weather. They are parthenogenetic, meaning that the females don’t require males in order to produce offspring. During the summer aphids give birth to live young, not eggs, making reproduction that much quicker. There are many different species of aphids: green peach aphid, foxglove aphid, melon aphid, and honeysuckle aphid, to name just a few.
How do I get rid of aphids?
The Science Behind it: You don’t have to worry about killing every single aphid on your rosebush. Rather, you just have to control their numbers. Spray affected plants with insecticidal soap. You can also try to attract more ladybugs to your garden, since they prey on aphids. You can buy ladybug lures at most garden centres. |
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