Question of the Month

Poinsettia caution

Poinsettia

Q. Are poinsettia plants poisonous?

A.The term "poisonous plants" is often associated with plants that may cause great harm or be fatal if ingested. Potential poisoning depends on the level of toxins contained in the plant and the amount consumed.

Insect leaf damage

Caterpillar

Q. I’ve noticed many leaves of my plants look chewed. What is causing this and is there anything I can spray to help my plants? 

 A. At this time of year, many different types of insects and their larvae frequently feed on the leaves of plants. Without seeing the culprit, it is not possible to determine which insect is causing the damage to your plants. Inspect your plants thoroughly in order to positively identify the insect causing the damage.

Lack of flowers on lilacs

lilac

Q. Why doesn’t my lilac bloom in the spring?

A. There are several possible reasons why your lilac fails to bloom. The most common cause is lack of adequate sunlight. Lilacs (Syringa) need to be planted in a location that receives at least six hours of strong, direct sun per day. They are very tolerant of different moisture conditions as long as they are planted in well-drained soil.

Watering tips

Q. How much water do plants need to keep them healthy?

A. The amount of water plants need depends on several different factors, like type of plant, how long it’s been planted, type of soil, and location.

Using fallen leaves in the garden

Q. How can I use fallen tree leaves in my garden?

A. Shredded leaves can be used to insulate various plants in the garden during the cold winter months. When leaves are used whole they can prevent water from penetrating the root zones of plants; therefore, it is important to shred them first. If only a small amount is needed, whole leaves can easily be shredded in a garbage can using a weed whacker. It is always a good idea to wear safety goggles when using a weed whacker. If a larger amount is needed, a lawn mower can be used.

Sprinklers and irrigation systems

Q: What types of sprinklers should I be using in my garden?

A:  There are many types of irrigation devices with distribution patterns to fit different watering needs. 

Hand-held devices or watering cans are the easiest to use for containers or specimen plants that may require higher amounts of irrigation.  Screw nozzles and pressure grips with triggers are available to distribute water in a variety of ways that range from full stream to fine mist sprays. 

How to prevent mums from getting spindly

Q: Last year my mums grew tall and spindly. Is there something I can do to prevent this from happening again this year?

A:  Hardy chrysanthemum plants can grow 1 to 3 feet tall, depending on the cultivar, with a spread sometimes equal to the height. To keep them growing optimally, they should be planted in a full-sun location that receives at least six hours of direct sun per day. Plants requiring full sun that are planted in shady areas will often stretch for more sunlight and grow straggly. The soil should be well-drained and kept slightly moist.

Overwinter Mums

Q: There are so many beautiful varieties of mums at this time of year. They are supposed to be perennial, but I lose them over the winter.  Is there a trick to get mum plants to overwinter?    

Gift Plant Recommendations

Q: I'd like to give plants as gifts for the holidays. Many gift plants are treated as short-lived houseplants because they are difficult to get to rebloom or keep alive and are discarded. Can you recommend plants that are easy to grow and that will last more than one season?  

Spring Rose Care

Spring Rose Care

Q. Do I need to prune my roses in spring?

A. Early April, or when the forsythia begins to bloom, is a good time to assess how your roses came through the winter, and to determine what their pruning needs might be. Many roses require minimal pruning at this time, primarily to remove dead or winter-damaged wood, whether that is the tip of a cane, or in some cases, the entire cane.

Winter Burn

winter burn

Q. As plants in my garden begin to green and produce new growth, I've noticed that some of my evergreens are very brown. Is this a disease? What should I do?

Winter Rose Preparation

Winter Rose Preparation

Q:  Is there anything I should do now to prepare my roses for winter? 

A:  Discontinue the fertilization of roses by the first week of August, approximately. Without supplemental fertilization, the plants will begin to shut down for the summer and will begin the process of storing nutrients to best survive the harshness of winter. 

Why is phosphorus, a component of lawn fertilizer, bad for the environment?

Phosphorus is a component of most fertilizers that helps plants to grow. When too much is applied or is applied at the wrong time—such as right before it rains—most of it is washed away and ends up in the local waterways. This type of pollution is called nonpoint source pollution. It causes eutrophication (a reduction of dissolved oxygen in water bodies caused by an increase of minerals and organic nutrients) of rivers and lakes. This reduced level of oxygen in water ends up suffocating fish.

Why is my hosta foliage turning brown?

Botrytis on hosta

A.  The cool, damp, cloudy spring we had this year is conducive to many fungal infections. Some of the more common fungal problems affecting hostas are anthracnose and botrytis. This season, Plant Information has seen many cases of hostas infected with botrytis, which can be prevalent in cool, wet weather. Botrytis on hosta first appears on foliage as water-soaked spots that begin small and increase in size. As the spots enlarge, cinnamon to dark tan rings can sometimes be seen within the lesions. Lesions can also travel down to the petiole of the plant.

Tomato plants don’t produce as much fruit

Tomato plant stress

Q. Last year, my tomato plants didn’t produce as much fruit as in past years. Why is this and is there anything that I can do about it?

A. There can be several reasons to explain low fruit production:

• Sometimes flowers drop off the plant during periods of fluctuating temperatures. Temperatures above 90 degrees Fahrenheit during the day can cause the blossoms to drop without setting fruit. If evening temperatures fall below 55 degrees, remain above 75 degrees, or if the humidity is too high, blossoms can also drop prematurely.

Aquatic Garden Preparation

Aquatic Garden

Q. I have a small aquatic garden in my yard. How do I get it up and operating for summer?

A. Performing basic maintenance on your water feature as part of spring startup will enable it to be a source of enjoyment throughout the warm weather. Here are the basic steps.

• Once the marginal plants begin to grow, remove the pond cover and trim back any dead foliage.

• Verify that pumps and other electrical equipment are operating properly and repair as necessary.

• Service any filters according to their manufacturer’s instructions.

Types of Strawberries

Types of Strawberries

Q. What is the difference between June-bearing and ever-bearing strawberries? 

A. Types of strawberries are named according to their harvest time. June-bearing strawberries are the most familiar type and produce the largest fruits as well as large yields. Ever-bearing plants produce two smaller crops, one in June and another in early fall. June-bearing varieties also produce larger numbers of runners than ever-bearing varieties.

Deadheading and Pruning Roses

Rose Care

Q: When and how should I deadhead and prune my roses?

A: Deadheading—the removal of spent flowers—is a form of pruning. Before making pruning decisions about your roses, it is best to determine the type of rose, and how and when it blooms. Roses are divided into different types based on common characteristics.

Pruning cuts should be made on a 45-degree angle, ¼ inch above an outward-facing bud or five-leaf axil. Dead, diseased, spindly, or crossing branches can be removed at any time.

Winter Evergreen Discoloration

Juniper in Winter

Q:  I recently noticed that some of my evergreens have become discolored. Should I be concerned?

A: It is normal for the foliage of some evergreens, such as arborvitae (Thuja) and boxwood (Buxus), to change color in cold weather. The different color of the foliage in such species is not indicative of a pathogen or cultural disorder; it is a normal response to winter temperatures.

Species that are known to change color in cold weather include:

Protecting Houseplants from Insects

Houseplant Care in Winter

Q: I have had problems with insects on my houseplants during past winters. Is there anything I can do to prevent or control them?

A: The first step is to keep insects out of the house by carefully inspecting any plants before bringing them into your home. This is especially important for plants that have spent the summer outdoors. If insects are found, isolate the affected plants immediately.

Planning on tomato plants

tomato seedlings

Q: I really want to start my own tomato plants this year. Am I too late?

 A: No, you are not too late. In the Chicago area, we do not recommend that tomatoes be transplanted into your garden until June 1. Since tomatoes require approximately eight weeks from seeding to transplanting, you do not need to start seeds until early April. However, starting tomatoes from seed, while a straightforward process, requires planning and preparation well before April.

Drill a Drainage Hole

Ceramic Pots

Q: I understand the importance of planting in pots with adequate drainage, but many of my pots don’t have holes. Every time I try to drill into the bottom of the pot, it cracks. How do I drill a drainage hole into a ceramic plant pot without cracking it?

A: The following process can be successful, but it is not guaranteed, and it is intended for adults with cordless drill competence.

Materials/Tools:

Deadheading Perennials

Deadheading Perennials

Q.  Will cutting spent flowers off of my perennials encourage more blooms? 

 A.  Removing old or spent flowers is known as deadheading. Most ornamental plants benefit from deadheading; however, newly planted young plants are less likely to require frequent deadheading in their first year of growth.

There are several reasons for deadheading. Most gardeners do it because it aesthetically looks better when dead plant material is removed, such as peonies and annual pinks (Dianthus chinensis).

Tomato Ripeness

Ripe Tomatoes

Q. How can I tell when the tomatoes in my garden are ripe?

A. Determining when tomatoes are ripe can be tricky, especially when we are anxiously waiting to sample the first tomatoes of the season. As a practical matter, the best guides to tomato ripeness, particularly for the heirloom varieties and those hybrids bred for the home gardener, are color and touch.