Best of Horticultural Tips for May
Trees & Shrubs
- Many houseplants will do well outside in warm weather, especially in partially shaded areas. Adding some to your containers will save money and create a different look. For sunny containers, look for tropical plants on sale.
- Iris borer damage shows up in May and June. Iris borers can be killed by hand. Simply squeeze the leaves.
- Hostas: work compost in around the plant and keep well-watered. Do not plant hostas beneath maple trees. The tree roots will take up most of the water. Mulch around the hostas, but not right up to the crown. This will help avoid crown rot.
- Daffodils may be divided when they are done blooming.
- If you want to give your perennials a nutrient boost, apply fertilizer to the soil when new growth starts. Compost or worm castings are natural fertilizers that feed the plant and condition the soil.
- Early spring, when the leaf points start to emerge, is the best time to divide clumps of hosta.
- Cut back winter-damaged rose canes to 1” below the blackened area. Make cure to remove all leaf litter out of the rose garden to help reduce diseases.
- Try planting ground covers in beds this year. As ground covers grow, less mulch will be needed. Some ground covers, like ajuga and lamium (dead nettle), also bloom.
- Hardwood mulch in the garden reduces water demand by as much as 40 per cent when spread at a 3-4” depth.
- Lightly side-dress perennials, including spring bulbs,with a 10-10-10 fertilizer. Avoid getting fertilizer in the center of the plant over the crown.
- Zinnias are among the quickest and easiest annuals to grow from seeds.
- Most flowers look better if they are cut for a vase before the buds open. In the morning blossoms are full of moisture and therefore less likely to wilt. But in the evening they have more food stored in their stems, which helps them to last longer in a vase. Just do not cut flowers mid-day.
- To renovate lilacs, remove 1/3 of old growth at the base.
- Look into flowering quince, one of the first spring bushes to bloom (red).
- DO NOT prepare for Japanese beetles by buying a trap. The lure will attract
insects from as far away as one mile!
- The first step in planning a successful garden is amending the soil with good compost. OmaGro is a great example if available. Then, mulch with organic material rather than rock. And NEVER use weed barrier fabric. The tiny roots of weed seedlings will pierce the fabric. Once the roots spread underneath the fabric, you will not be able to pull the weeds out. Instead, use thick layers of newsprint (not the shiny ads or magazines.) The newsprint will eventually decay and add to the garden soil.
- Want more flowers? Look for fertilizer with a higher middle number (P), the nutrient that stimulates blooms.
- You can also sprinkle a slow release fertilizer around perennials as they start to emerge in spring.
- Plan to stop feeding perennials and shrubs by mid August so that new growth is not damaged over winter.
- Nutsedge, which is light green with a triangular stem, will show up when temperatures rise consistently to 60 and above.
- Control nutsedge with products like Sedgehammer or Dismiss.
- Weeds in buffalo grass can only be sprayed for control in November and December.
- Buffalo grass may be seeded in spring. Cover seed with ¼” to ½” of soil. Apply fertilizer 18-24-6 every four weeks. This type of grass does not grow well in shade.
- Tall fescue grass is shade tolerant.
- White clover in lawns can be controlled with Triclopyr. However, it is worth considering that white clover will make bees happy at the same time that it adds nitrogen to your soil.
- Spray violets in the lawn while temperatures are still cool and before the plants have developed the protective, waxy covering on their leaves. Weed-Be-Gone works well.
- Grass seed can be started any time until the end of May. After that time, you are better off waiting until next fall.
- Setting the mower at 3” all year long helps shade out weed seed germination.
- Remember to always keep a sharp lawnmower blade on hand. Change the blade each month for best results.
- Nitrogen needs:
KentuckyBluegrass: 2-4 lbs. N/1,0000 sq ft./year
Tall Fescue: 1-3 lbs. N/1,000 sq. ft./year
Buffalograss: 1-2 lbs. N/1,000 sq. ft. /year
This amount cannot be put down all at once! Divide the amount by the number of times you want to apply (generally 4-5). Easy schedule to remember focuses on holidays: Arbor Day, Memorial Day, Labor Day, Halloween, Thanksgiving. Never fertilize during the hot months, especially July. That will overstress the grass.
- Mid-Sept. through late October is the best time to control dandelions by putting down pre-emergent and/or hand spraying.
- If the turfgrass plant cannot take up the nutrients, simply applying fertilizer will not increase the amount of nutrients the grass takes up. Make sure you have a soil test done every few years to check on the soil PH.
- The simple act of cutting a leaf blade is stressful for a grass plant. The grass still has to recover from a wound and a there is a reduction in the plant’s energy-making factory, the leaves.
- Crabgrass completes its life cycle in one year: germinating from seed in spring, growing throughout summer, and setting seed in fall. The most effective means of control is using a preemergence herbicide in the spring, after ground temps hit the mid-50’s for several days in a row.
- If tall fescue is mixed in with buffalo grass, don’t spray now. Wait until fall after a killing frost to spray with Round-Up.
- Annual bluegrass is a winter annual, so there is no need to control. It will die in the heat of summer.
- Prostrate knotweed is an early summer annual. No need to spray; it will die in fall.
- Spread lime on the lawn only if a soil test indicates a ph value of 6 or lower. Aerate before applying the lime.
- September 15 through October 15 is the best time to kill dandelions. Right now, go out and dig while the ground is so wet. You should be able to get the entire root.
Trees & Shrubs
- Be on the lookout for bagworms. Pull the bags off trees or shrubs and dispose of in the trash. DO NOT throw them on the ground as the insect will still be inside. It does no good to spray this early as no chemical will be able to penetrate the bag.
- Looking for an interesting tree? Flowers on a Paw-Paw tree grow upside down.
- Crabapple trees can be pruned in the summer.