A clean garden is a healthy garden. Be vigilant in removing weeds and weak or diseased plant material. Mulch minimizes weeding work, and, with many types available, you can determine the most effective choice for your space and sense of aesthetics. Hay and wheat straw work well in the vegetable garden because they break down into good organic material quickly and can be tilled directly into the soil at the end of the season. Bark and pine straw last longer and are good for around trees or among the perennials. Then there are all the others on the market now, such as rubber and recycled plastic, black or white plastic, etc. Investigate which ones suit your purpose..
Brew some compost tea for your flowers: Fill an old pillowcase or burlap bag with compost (even manure or mushroom compost you buy at the store) and tie the top with twine. Tie the twine to a stick and suspend the bag in a bucket of rainwater or water from the tap that has been allowed to sit for a day or two. After just a few hours, you’ll have a good brew that won’t burn your young seedlings.
Roses will benefit from a slow release fertilizer this month. Keeping air circulating around your roses will help cut down on disease. Remember to pick up yellowed leaves from the rose bushes and the ground. Do not compost them.
Plant a few extra ‘Knock Out‘ roses. The selection of colors is expanding.
Watch for aphids attacking new plant growth and spray with a liquid soap, followed by a strong blast from your garden hose. (If you see lady bugs in your garden, look for aphids.)
To aid the germination of your nasturtium seeds, rub them with a nail file. Sow them in full sun, 12 inches apart and cover lightly with only ½ inch of soil. (Soaking them overnight can also help with germination.)
Sow poppies at the end of May, in warmed soil and in full sun.
Plant caladiums once the soil temperature has reached 70 degrees. (5-7 consecutive days of 70-plus degree temperatures will create a soil temperature of 70 degrees.)
Remove damaged or brown leaves from hostas. Look for snail damage as weather warms. Pick them off by hand and drop them in soapy water.
Divide hostas this month. Dig them with a garden fork, not a shovel, so their long roots are not damaged.
Planting marigolds in the garden and vegetable patch is legendary for repelling bad insects and attracting the good ones, such as the hoverfly (whose larvae eat aphids). The adult hoverfly works as a pollinator throughout the garden. They are attracted to the orange and yellow of the marigolds.
Continue planting beets, carrots, chard, chives, lettuce, onions, parsley, parsnips, radishes, shallots, spinach, and turnips.
You may enjoy trying Malabar Spinach this season. It performs well even as temperatures warm, unlike other spinaches, and is not bothered by insects. The vigorous vines with tasty red leaves can climb to 8 feet, when trellised. (It came from East Asia in the 1800’s.)
By mid month, you should be able to plant the heat loving crops such as tomato, okra, corn, peppers, melongs and squash. Wait for the soil temperatures to heat up.
As your tomato seedlings grow, clip off the lower branches to keep any leaves from touching the ground. This will help keep soil-borne diseases off the plants. It also helps the plant concentrate its energy on the blossoms and fruit, not on all that foliage. Newspaper covered with hay around tomato plants keeps soil from splashing on the plant.
This month you’ll be harvesting asparagus. Remember that when the shoots start to thin, stop cutting them and let them grow their ferny foliage and nourish the roots for next year. Established roots will give you about six weeks of harvest before the shoots begin to thin. If this is your first year of harvest, only cut the shoots for a couple of weeks before letting them grow up. Fertilize in spring and fall by top-dressing with liquid fertilizer (such as compost tea) or side-dressing with a balanced organic fertilizer.
Your broccoli, cabbage and cauliflower are maturing. If bugs are a problem, use Bacillus thuringiensis (BT) to control cabbage looper caterpillars. Row cover works well on these, too.
If you’ve planted potatoes, keep hilling them up as the plants grow taller. You can use soil or moist mulch (rotted hay, compost, etc.) to cover the bottoms of the plants. This gives the plant room to grow the tubers. Make sure all surfaces of the tubers are covered. Sunshine will turn them green which makes them toxic. You’ll be harvesting early-crop potatoes in June.
Apply a slow release granular fertilizer or a layer of compost to spring blooming shrubs after the flowering is completed. Prune them then, too, if they need it. They will start setting next year’s blooms midsummer, so get pruning chores done before that.
Use a horticultural oil on azaleas that have shown signs of lace bugs (mottled and yellowing leaves).
Treat Otto Luyken Laurels with an oil spray for mites, spraying the back side of leaves. The mites are barely visible, and often are on the underside of leaves. If you suspect mites are attacking your bushes, take a plain sheet of white paper, place it under the branch, and tap the branch. If you see red specks on the paper, you have spider mites.
Only prune young trees to remove dead or broken branches.
Lawns do best when they are soaked once a week and then allowed to dry between waterings. This allows grass roots to breathe. In spring and early summer, irrigation is rarely needed. Remember: if the soil is moist, do not water.
If you have an irrigation system, check for clogged ‘heads,’ cleaning or replacing as needed. Get to know the irrigation clock or timer, and adjust the run time when we have more rain.
Although results can vary, most herbicide labels do not recommend core aeration after a preemergence herbicide application. The core aeration may stimulate crabgrass growth.
For your best cut, keep your mower blades sharp. Consider installing a mulching blade, the next time you need to replace it. Mow often and keep the grass 3-4 inches tall, cutting no more than a third of its length each time. Let the clippings stay where they fall to return nutrients to the soil.