May Gardening

There are just a few of the ways you can efficiently use water in your garden:

• Mulch, mulch, mulch!
• Water deeply and less frequently, instead of often and shallowly.
• Water early in the day.
• Wherever you can, use soaker hoses or drip irrigation systems.
• If you use sprinklers, don’t set them so high that they give off a mist, which will just uselessly evaporate away.

And speaking of water, if you happen to have a pond or other water feature in your garden, it’s time to start cleaning it up and ensuring your pump is both clean and in good working condition. Place mosquito dunks in your pond to keep mosquitos under control. If your pond has water lilies that were sunk for winter protection, it is time to raise them back up closer to the surface. You should also feed them with water lily fertilizer tabs.

May is an excellent time for planting annuals like Impatiens, petunias, salvia, and bacopa! You should only delay planting if it is still unusually cold at night. When planting your annuals, pay attention to the maximum spread and allow each individual a little room to grow. Adding granular, time-release fertilizers after planting can help keep the plants fed for the next several weeks, encouraging vigorous growth and abundant flowers.

As for perennials, the season started a while back, but it’s still going strong. Many heat-loving perennials—such as Echinacea and other daisy-like plants—are not available until May. 

As for your existing perennials, tidy and fertilize if you have not already done so this spring. Most perennials should be growing well now and can use the nutrition. You can also add a thin layer of compost on top of the soil to improve the soil and temporarily suppress weeds. Get those peonies, dahlias, and other floppy growers caged so that the blooms will stand up well later on. It is best to get the cage set before the plant has grown up to the height of the grid or ring. If the plant is already tall, be careful to gently tuck the foliage into it. This is probably the last acceptable time for any dividing before the heat of summer.

May and June are the best times for planting heat loving tuberous plants such as begonia and dahlia. For bulbs that are blooming or just finished, go ahead and feed them if you have not yet done so this season. Do not remove green leaves from bulbs—even if they are floppy. They usually only last a while and the plants need to be absorbing as much sunlight as possible.

Pests are definitely rearing their ugly little heads. Aphids are spreading rapidly and slug populations can get large this time of year. These can be controlled with insecticidal sprays or baits, many of which are safe for people and pets if not misused. If you’re unsure if aphids are present, a quick glance at the new growth or blossoms will give them away. Look for their soft bodies and dandruff-like, molted skins on or near the new leaves. If you have seen what looks like saliva on rosemary, lavender, and other plants, you are seeing spittlebugs. While unsightly, they are usually fairly harmless. 

Ever heard of the thriller, filler, and spiller rule? The basic idea is to get a combination of plants with different growth habits to create a lush, full container display. Visit our Thriller-Filler-Spiller Page to learn more and see a few examples.

May is a great time for planting woody plants. The soil is warming and drying a bit, and digging shouldn’t be too hard at this point. When preparing the planting site, remember that the soil underneath the root ball should not be loose; it will compact later and the stem will end up buried too far, often killing the plant. This is especially true of balled-and-burlap (B&B) trees that have a clay-based soil in the root ball.

This is also a fine time for feeding your established trees and shrubs if you have not done so recently. Mature trees and large shrubs may not need feeding. If they grow and bloom just fine, it probably isn’t necessary.

Roses are just getting ready for their first blooms of the year. Feed them as well and watch for pests. Aphids may have set in, and fungal diseases such as black spot may be starting.

As established hedges start to grow, this may be a good time to trim for size and shape. Lightly feeding them after doing so can encourage a fresh flush of growth that will minimize the visual impact of your trimming. Of course, this might mean more frequent pruning with fast growers.

Rhododendrons and other spring flowering evergreens can be pruned just after bloom. This may be the only good time of year for mild to moderate pruning, as pruning late in the year can ruin the flowers for next year.

With most shrubs, the trimming just mentioned is for mild trimming for size and shape. Removal of large branches is often better for the plant if done in winter.

May is generally the first month recommended for planting most warm-season vegetables, such as tomatoes and eggplants. That said, you’ll need to keep them protected until the temps are steadily above 50°F—and that usually happens around mid-June. Some people start their squashes and melons in May, although June is often a better time for them as well. For those who have already planted, several products are available to keep your plants cozy.

When you do plant fruiting veggies (e.g. tomatoes, squash, peppers, etc.), make sure to add some lime to your soil. This is especially important for tomatoes and squashes, as it helps to prevent blossom end rot.

If you started seeds indoors or in a greenhouse, it may be warm enough to acclimate them to outside temperatures and plant them—but they will still  be susceptible to cold damage, so keep an eye on nighttime temps.

It is not too late for most greens and cole crops (e.g. cabbages, broccoli, and their kin), but the sooner the better. If it gets hot early in the growing season they may bolt, ruining the crop. Please refer to our vegetable planting calendar for further timing details.

Wash the leaves of indoor plants and check/treat for pests and diseases. If you suspect you have a problem with a plant and are not sure what it is, bring a sample to our Info Desk. We carry a full line of safe products for houseplants and tropicals.

It’s time to be feeding most indoor plants as they actively put on growth. We have several types of indoor plant food and recommend Dyna-Gro Pro as a good, all-around fertilizer. Give us a call if you have questions on feeding or care of specific indoor plants.

Start setting houseplants outside in a shady location for some fresh air. If you have any questions about particular plants and where they like to spend their spring and summer, feel free to call either shop.