How to keep the blooming party going in your garden

Take photographs of your bulb displays now and throughout the month as they come into flower. Think about where new bulbs may be added this fall to improve the display.

Some bulbs thin out over time and need occasional replenishing for a consistent year-to-year display. Observe your garden over the course of spring and early summer and plan to add bulbs that bloom at different times to extend color. This will make it much easier when you are ordering and planting bulbs later this year.

Remove any rogue bulbs that may have seeded themselves around the garden — they are easy to spot when they are in flower.

• If your soil is too alkaline, elemental or granulated sulfur can be added to lower the pH level. Rhododendrons and azaleas, for example, can benefit from sulfur applications in many gardens in the Chicago area.

If your blue hydrangeas are turning pink, apply sulfur to turn the flowers back to blue. The flowers turn pink in more alkaline soils. Add 3 pounds of sulfur per 100 square feet of garden area per year. It is best to apply in both spring and fall, applying one-half of the recommended rate each time. Work the sulfur into the soil and water in. Sulfur is slow-acting. Wear protective gloves and be careful to keep the dust out of your eyes when applying.

• Avoid applying crabgrass control to your lawn as an annual maintenance task. If you did not have problems with crabgrass last year, you probably do not need to apply crabgrass control this year.

Pre-emergent herbicides (like those sold for crabgrass) work by preventing the weed seeds from germinating. These herbicides need to be applied before weeds germinate. Generally, crabgrass controls are applied to lawns in early to mid-April and need to be done before lilacs begin to flower. These products also prevent new grass seed from germinating and are less effective if disturbed by maintenance activities such as core aeration.

• Tim Johnson is director of horticulture at Chicago Botanic Garden,

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