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May Gardening Tips

deer fern


General Gardening Tips

May is projected to continue the trend of being a bit cooler than usual.  Tender or heat-loving plants, such as geraniums and tomatoes, may need to go out later than usual or be given protection. See the tomato tips for suggestions. 

Bait for slugs with pet and wildlife safe slug bait such as Sluggo.

Weed! Any weed you pull before it sets seed reduces your work later.


Vegetable and Herb Gardening Tips

Time to plant:  Early May marks the end of the spring planting season for cool-season veggies. If you haven’t planted your greens, cabbage family crops, root crops, and peas, get them in as soon as possible.

Here at Sky, we’re beginning to make way for hot-season crops. This is your last chance until about August for most cool-season veggies!

Almost all herbs can go right in the ground now. A few tender herbs like basil and lemon verbena need protection from cold nighttime temperatures.

Hot-season veggies and herbs can be planted with protection from cold nighttime temperatures in early May, or without protection in late May. 

Tomatoes: We carry over 100 varieties of tomatoes here at Sky, all grown in Washington and Oregon using sustainable growing practices. You can find some basic tomato information, along with a list of the varieties we plan to carry this year, here

If you’re itching to plant your tomatoes, make sure they’re protected! Season extension tools are even more important than usual because we’re having such a cool spring. Portable options like Hotkaps and Wall O’ Waters work great in both veggie beds and container gardens. We have everything you need to protect your tomatoes and other hot-season veggies here at Sky. 

For those restricted in space, we have Tomato Barrels, easy-to-store Tomato Planter Bags, and more. 

Hot Season Veggies and Herbs: Beans, squash, corn, eggplant, cucumbers, and basil need nighttime temperatures above 50°F. Usually, that happens around mid-May here, although it may be a bit later this year. In the meantime, make sure to protect all hot-season veggies and herbs. 

apple tree blossoms

Berry & Fruit Gardening Tips

Monitor fruit trees and berries for insect and disease problems; consult a Sky Nursery associate for recommendations if you spot an issue.

Do not spray any insecticides, even organic ones, on fruit trees or berries in bloom. If disease problems require a fungicide treatment, use the least-toxic product and spray at dusk or very early morning to reduce impact on pollinators. Once the petals drop, you can resume spraying insecticides if needed. 

Thin apples and pears when the fruit is under a nickel size to improve cropping consistency.

Apply apple maggot barriers or Surround clay once you’ve thinned your apples or pears.  Surround may need to be re-applied depending on rainfall.

Fertilize with organic fertilizer.

Remember to water regularly when the rain stops (soon, we hope!). Even a week long drought can cause fruit drop.

Ornamental Gardening Tips

Fertilize rhododendrons after bloom and remove spent flowers to keep plants tidy.  If you need to prune at all, now is the best time to do so.

Prune spring flowering shrubs after bloom.

Remove spent flowers from spring flowering bulbs; leave foliage as long as it is green, because the bulb is storing energy for next spring’s bloom.  Tip: you can fill in with fast-growing annuals around your spring bulbs to provide color and interest while the bulbs are fading out.

Native plants, being adapted to our soil and climate, are naturally easy to care for.  And they appeal as much to wildlife as to humans, attracting birds and pollinators to your garden.  May and June sees Sky’s best selection of native perennials such as shooting star and false lily-of-the-valley.

May is also your last great chance to get major plantings established before summer’s heat and drought, which can be stressful for transplants.  Sky has an excellent selection of all the plants you’ll need, from specimen trees and shrubs to perennials, groundcovers, and ferns. 

For roses, apply a little alfalfa, kelp, and Epsom salts to boost their immune systems.  Watch for aphids on tender new growth (talk with a Sky sales associate for earth-friendly controls).

Planter and Hanging Basket Tips

Sky has a great selection of gorgeous hanging baskets and custom containers, plus tables upon tables of starter plants for putting together your own.  Don’t see quite the container you want?  Our container design department can custom-create one just for you.

Fertilize heavy-blooming annuals in containers or baskets every two weeks with a good liquid fertilizer.

Once night-time temperatures stay consistently above 50°F (10°C): Geraniums, begonias, coleus, sweet potato vine, and other warm-weather lovelies are safe to leave outside without protection.

Lawn Care Tips

Mow!  If possible, leave your clippings (grass-cycling). 

The grasses that do the best in the Puget Sound area are what are known as cool season turf grass.  This means that as the summer heats up, lawns will go dormant unless watered regularly.  Your lawn needs 1 to 2 inches of water per week. Once rains stop providing that, it’s up to you whether you prefer to water or let your lawn go dormant. 

Setting your mowing height higher can reduce water needs by shading the ground and promoting deeper root growth.  Improving your soil with extra compost can also promote deeper root growth and increased drought resistance.  Healthy turf will weather drought stress better, so make sure your grass starts the summer in good shape by following a good fertilizing and liming schedule. 

If you haven’t fertilized yet this spring, do so ASAP with a good organic fertilizer.  If you’re following our recommended four times a year schedule, your next feeding will be at the end of the month (Memorial Day).

If weeds are a problem, try pulling or spot-treating rather than using a weed & feed product.  Remember that a well-fed lawn can outgrow most weed problems.

Water Gardening Tips

Water plants are here!  We have floating plants like water hyacinth, reeds and cattails to ornament the edges of your pond, oxygenators to keep your fish happy, and more. Wait for warmer weather, though, to look for the more tender exotics like papyrus. 

If you have water lilies, now is the time to re-pot and fertilize them.

Sky also carries a full line of pumps, replacement parts, and pond test kits—everything you need to keep your water feature, big or small, in top condition. 

If you have fish, they should be active by now. Watch your water temperature and fish activity level to know when to start feeding. Pond temperatures should be above 50°F before you begin feeding your fish, and even then you should start slowly, with frequent small feedings of a low-protein food.

Viburnum Tinus

As always, we’re here to help. See you soon!