Black walnut (Juglans nigra) has a reputation for being allelopathic – that is, for inhibiting the growth of other plants. Small amounts of juglone are released by the tree roots, but a far greater amount of this growth-inhibiting chemical is found under the canopy of the tree.

Some plants that are tolerant to juglone include: arborvitae, cedar, catalpa, clematis, daphne, elm, euonymous, forsythia, hawthorn, hemlock, sycamore, astilbe, begonia, bellflower, hawthorn, hemlock, sycamore, astilbe, begonia, orange hawkweed, hosta, pansy, phlox, marigold, primrose, snowdrop, sweet woodruff, trillium and zinnia.

Avoid plants that are sensitive to juglone, including apple, pear blackberry, blueberry, asparagus, cabbage, eggplant, pepper, potato and tomato.

Landscape plants sensitive to Juglone include azalea, birch, honeysuckle, hydrangea, larch, lilac, magnolia, maple, pine, potentilla, rhododendron, spruce and viburnums.

Also, keep in mind that walnuts fall and may damage whatever you plant beneath the tree.

The spring series of University of Illinois Extension's Four Seasons Gardening starts April 8. Each seminar features a color slide presentation accompanied by the voice of the instructor as people from all over the state participate

All sessions, both afternoon and evening, will be presented in Carroll County; NOTE: only the afternoon sessions will be held in Jo Daviess County. Cost per session is $5. or the entire 3-part spring series is $12. Pre registration is required. Register by calling your county extension office (Jo Daviess 815-858-2273, Carroll 815-244-9444) or email using the Unit web address: http://web.extension.uiuc.edu/jdc If you have disability needs, please indicate when registering.

Orchids 101. Have you ever wanted to grow orchids but been scared off by their "diva" reputation for high maintenance and a high price tag? Learn how to select orchids suitable for the home and how to keep them alive once you get them there.

Jennifer Schultz, U of I Extension horticulture educator, will present the program. The seminar focuses on the basics of growing and caring for orchids. It will be presented at 1 pm on Tuesday, April 8 and repeated at 7 pm on Thursday, April 10.

Containers with Pizzazz. Tired of the same old plant containers on your porch, patio or deck? Plan and plant for pizzazz! This session offers ideas for design, containers and plant combinations.

Jennifer Fishburn, U of I Extension horticulture educator, and Karen Grant, U of I Extension Master Gardener, will present the program. Those attending will get new ideas for containers and how to put together plant combinations for a beautiful visual impact. It will be presented at 1 pm on Tuesday, April 22 and repeated at 7 pm on Thursday, April 24.

A Palette of Annuals: A to Z. Why limit yourself to marigolds when there are so many annuals for your garden? This session will cover old favorites as well as some of the newer introductions.

Jim Schmidt, U of I Extension horticulture specialist, will present the program. It will be offered at 1 pm on Tuesday, May 6 and repeated at 7 pm on Thursday, May 8.

In May, when it's time to scratch the planting itch, before you run out to the garden center and hand over your plastic, it's a good idea to have a buying strategy. Here are some suggestions:

Get to the root of it. Before buying a plant, especially a pricey perennial, gently pull it out of its pot and check the roots. Are they plump and white, or brown, rotted, and stinky? You can expect most plants to be root-bound in their pots by now, so that shouldn't put you off from buying, as long as the roots look healthy. On the other hand, it you're considering a larger, and more expensive, container, checking inside the pot will tell you if you're actually paying for more plant, or if the plant's roots only extend a couple of inches into a big pot. In the trade, they call that "buying dirt", and it's certainly not a good value.

Pick your day carefully. Most garden centers gear up for big weekend sales by bringing in fresh inventory mid-week. That usually means that early in the week, pickings will be slim. On the other hand, going plant shopping on a weekend is garden masochism, just you and a thousand desperate gardeners fighting over the Big Daddy petunias. Best bet: go on Fridays, when the shelves are fully stocked and the inventory is in prime condition.

Check the cottage (garden) cheese. Careful shoppers at the supermarket check products for their expiration dates. Although plants don't carry expiration dates–if they did, they would most definitely be three days after you planted them–there are fresh plants and not so fresh plants. Just like at the supermarket, it pays to shunt aside the weary products in front and go digging for the good stuff. Look around you; sometimes the newer plants are on the ground or the lower shelf below the display table, or they may be on a large cart off to the side, awaiting shelf space.

Size Matters. Usually, you get what you pay for. Given my druthers, I'd rather buy several four-inch pots of lobelia than a flat of little cells. The root systems are better developed, and in the interest of "Time is Money", you will save a lot of time and effort in transplanting six larger plants than 48 little seedlings. While this is true of annuals, it is even truer when it comes to perennials. If you've ever mail-ordered a hosta, and received a three-inch tall plant that took four years to attain even dwarf status, then you know what I mean. Not only is it esthetically disappointing, but given our potentially harsh temperature range, perennials planted in our area need to be sturdy in order to survive. Buy the biggest plant you can afford, now.

The Beijing rule of shopping. Years ago I went on a trip to China. The first stop was Beijing, and the very first day there our government guides herded us into an enormous government-owned shop filled with merchandise. A lovely gold necklace caught my eye, but because it was Day One and I was certain we'd be visiting a dozen more government-owned shops with identical merchandise, I stifled the urge to buy it. Of course I never saw that necklace again. At the garden center, there's little risk that you won't see red petunias or yellow marigolds coming and going, but maybe not that odd plant that makes you smile. When you see it, go for it. Tomorrow–maybe even in ten minutes–it may be gone.

The Shanghai corollary of shopping. You've estimated that you need two flats of impatiens 'Elfin Coral Sparkle with Purple Eye' for your front yard, so that's what you buy, right? Wrong. Buy an extra dozen plants, at least. If matching up colors is important for your space, don't cut it too close. Some cells in the interior of the flat may be empty, some plants may bite the dust tomorrow, and in any event you'll always find a place for the extra seedlings. Tomorrow, that one color of impatiens will be the only one that has sold out, guaranteed.

Read plant tags carefully. No matter what the helpful little sign on the display table says, pull a plant's tag out of the soil and read it, every single word. You're looking in particular for highly technical buzz words such as "sun" and "water". Like real estate, gardening is about location, location, location. Beware of certain stock tag phrases, like "needs constant moisture" (needs more water than any of us will ever give it), "fast-growing" (invasive), or "potentially invasive" (don't even think about it).

Nip it in the bud. Don't be seduced by plants full of blooms. Root-bound annuals start putting their energy into producing flowers, because there is nowhere else to go. What you will end up with is a stunted plant with leggy growth and few more blossoms. Look for plants whose flowers are just starting to bud out, with perhaps one or two blooms. If all the plants are in full bloom, pinch off the buds when you get home. You will get a better root system and bushier plant.

- MaryAnne Spinner, U of I Ext. Master Gardener, Chicago

When selecting perennials for the home landscape, it's important to consider their size, bloom period, hardiness, and cultural requirements. Another consideration is their longevity. Some perennials are extremely long-lived. For example, it's not uncommon to see 50- to 60-year old peonies in older neighborhoods. In contrast, some perennials tend to be short-lived. These short-lived perennials persist for several years and then decline and fade away.

A list of long-lived and short-lived perennials is provided below. If given proper growing conditions and good care, long-lived perennials often persist for 20 or more years. Short lived perennials usually disappear within 10 years.

Long-lived Perennials

Monkshood (Aconitum spp.)

Lady's Mantle (Alchemilla mollis)

Goatsbeard (Aruncus dioicus)

Butterfly Weed (Asclepias tuberosa)

False Blue Indigo (Baptisia australis)

Snakeroot (Cimicifuga racemosa)

Gas Plant (Dictamnus albus)

Ferns (various species)

Hardy Geraniums (Geranium spp.)

Ornamental Grasses (various species)

Daylily (Hemerocallis spp.)

Hosta (Hosta spp.)

Siberian Iris (Iris sibirica)

Blazing Star (Liatris spp.)

Daffodil (Narcissus spp.)

Peony (Paeonia spp.)

Balloon Flower (Platycodon grandiflorus)

Lungwort (Pulmonaria spp.)

Black-eyed Susan (Rudbeckia fulgida 'Goldsturm')

Stonecrop (Sedum spp.)

Carolina Lupine (Thermopsis caroliniana)

Short-lived Perennials

Columbine (Aquilegia spp.)*

Tickseed (Coreopsis grandiflora)*

Delphinium (Delphinium spp.)

Pinks (Dianthus spp.)

Blanket Flower (Gaillardia x grandiflora)*

Baby's Breath (Gypophila paniculata)

Coral Bells (Heuchera spp.)

Hyacinth (Hyacinthus orientalis)

Shasta Daisy (Leucanthemum spp.)

Perennial Flax (Linum perenne)*

Lupine (Lupinus hybrids)

Maltese Cross (Lychnis chalcedonica)

Iceland Poppy (Papaver nudicaule)

Pincushion Flower (Scabiosa spp.)

Painted Daisy (Tanacetum coccineum)

Hybrid Tulips (Tulipa spp.)

*Freely reseeds

- Richard Jauron, Iowa State Universtiy Extension

*Poison ivy grows as a shrub or as a woody vine that can reach up to 60 feet long and. The compound leaves have three leaflets giving rise to the old saying, "leaves of three, let them be."

*All parts of the plant are poisonous and contain a toxic oil called urushiol, which is responsible for the severe itching and blistering of the skin.

*In the fall, leaves turn a bright red-orange color and vines can be easily seen growing up the sides of trees.

*Even in winter, contact with the plant sap can cause a reaction and produce a skin rash.

*Burning poison ivy after it has been cut or trimmed is hazardous. The smoke from burning plants can cause injury to the eyes, skin and respiratory tract.

*When dealing with poison ivy, avoid all contact with skin by wearing gloves, long pants, socks, shoes and a long-sleeve shirt

*If you are exposed to poison ivy, immediately wash the oil from your skin with soap and water to minimize the allergic reaction.

*Only 1 nanogram (billionth of a gram) is needed to cause rash.

*1/4 ounce of urushiol is all that is needed to cause a rash in every person on earth.

*1 to 5 years is normal for urushiol oil to stay active on any surface including dead plants.

*Rubbing the rashes won't spread it to other parts of your body (or to another person). You spread the rash only if urushiol oil has been left on your hands.

- George F. Czapar, Ph.D. University of Illinois Extension

Ornamental Grass:

Cut back the foliage to about 4-6 inches in the spring before growth resumes. When foliage is removed, spring growth will begin earlier. Old foliage left on the plant can delay the crown's warming and subsequent growth by as much as three weeks. Grasses do not need to be cut down before winter. In fact, they are attractive and the foliage helps to insulate the crown of the plant.