The River Valley’s last frost occurs around mid-April. You can get away with planting frost-sensitive plants earlier if you are prepared to do some protecting when frost is predicted.

April highlights include Easter Sunday (today), deadline to file your 2017 income taxes on April 17 (because the official April 15 deadline falls on a Sunday), and Earth Day on April 22. This year, Earth Day's focus is on ending plastic pollution, especially support for an effort to eliminate single-use plastics and regulations for disposal of plastics.

And while the temperatures have been jumping all over the chart, it’s time to get ready for spring gardening. Here’s a “to do” list for mid- to late April:

• Early treatment can prevent damage by cabbage worms on cole crops such as cabbage, broccoli, and cauliflower. Cabbage looper, diamondback moth caterpillar, and the imported cabbage worm can cause serious damage. Check weekly for eggs and larvae under the leaves. Use Bacillus thuringiensis (BT) spray as soon as they are first noticed. These vegetables are heavy feeders of nitrogen and can use a side dressing of nitrogen three to four weeks after planting.

• To grow monster size onions, fertilize weekly with a water-soluble fertilizer and mix at half rate.

• Wait until mid month or later to plant warm season vegetables — or you may have to replant. You may want to delay planting okra, peppers, southern peas and sweet potatoes until late this month or the first of May. Warm soil temperatures are critical for these vegetables.

• Spray hybrid tea roses with a fungicide to prevent black spot. Follow label directions.

• Wait to fertilize bermuda or zoysia grass lawn until it has fully greened up — usually around mid-May.

• Prune and fertilize spring blooming trees and shrubs immediately after bloom. Remember to remove the old canes of forsythia, quince, weigela, spirea and other cane producing plants.

• Summer bulbs such as cannas, caladiums, dahlias, gladioli and tuberoses can be set out in later this month. Plant gladioli several times at two-week intervals for blooms throughout the summer.

• Continue to divide summer and fall blooming perennials.

• As flowering bulbs fade, allow six to eight weeks of green growing time for bulbs to replenish their nutrients. Crocus and daffodils do not have to have their flower heads removed, but it is beneficial with hyacinths and tulips. Fertilize with complete fertilizer. You can transplant and divide spring flowering bulbs after foliage begins to die down.

• Keep birds away from strawberries with bird netting. Watch for slugs.

• Attract butterflies by planting butterfly weed, parsley, dill, fennel, rue, passionflower, and tulip tree. These will nourish the young caterpillars after they hatch.

• Plant seeds of annual vines such as hyacinth vine, moon vine and cypress vine later this month.

• Mulching is your best method to prevent weeds, plus it maintains soil temperature and moisture.

• Aphids can occur in large numbers in the spring. Aphids dine on the sap of an endless number of plants but can be controlled with malathion or insecticidal soap. But be aware and be vigilant: a second invasion can occur within days.

Jayson McGaugh is the Sebastian County Cooperative Extension agent. Have questions about lawn, garden or other horticulture-related issues? The Sebastian County Extension Service can help with offices in Barling and Greenwood. Call (479) 484-7737 for answers to horticulture questions.