Happy May! The weather is now warming up day by day, with nighttime temperatures still in the low 40s, with the occasional dip in the high 30s, but the danger of frost is over. The plants are fully awake, and the garden is brimming with life. As the fruit tree blossoms fade, the viburnums are taking their turn on the flowering stage. The ornamental onions are starting to show color, and in a few weeks, peonies will be in full glory. The garden is now fully abuzz with bees and other insects. What a welcome to mid-spring!
garden Borders and beyond
Deadheading and Chelsea chopping
Deadhead your hellebores, muscari (grape hyacinths) and daffodils if you haven't done so, unless you want hellebore seedlings (which rarely come true to type and, more grape hyacinths than you know what to do with. Deadheading conserves energy for the daffodils to flower strongly next year.
You can still dig up and divide perennials. Just make sure you keep them well watered till they are established. If you haven't applied mulch, May is a good time to get the mulch on to keep weeds down and to retain moisture as we head into the rainless summer months. If they tend to flop, this is also a good time to stake your rapidly growing peonies, irises, and lilies. The emerging foliage will grow around the stakes and disguise the stakes, and will look more natural than trying to stake the plants up after they flop. Enjoy the lushness of the May garden, as leaves fill in and flowers bloom.
Another technique is to "Chelsea chop" (the Brits call it so as it coincides with the Chelsea Flower Show in mid to late May) your tall perennials such as sedums, nepeta and tall geraniums that tend to flop over. By cutting back the foliage to 2/3 or 1/2 height now, it ensures that the plant will grow stockier, and won't flop later on, although they will flower a little later. You can "Chelsea chop" half of the plants so you have a longer bloom period with the taller plants flowering earlier, and the "Chelsea chopped" plants will follow with a slightly later bloom time, to extend the flowering period.
in the vegetable patch
Tomato and Squash time!
Outdoors: Everything can be sown safely outdoors this month, although beans and cucurbits should be planted when the soil temperature is around 60 degrees. Transplants of brassicas, leeks and cool weather crops can be set out in the garden in early May, but transplants of tomatoes and peppers should be put in the ground in mid to late May, unless under cloche, as they like warmer soil temperatures. Stop sowing seeds of cool weather vegetables by the first week of May, and start sowing seeds for warm weather crops.
Indoors: Basil can be started indoors to plant out in late May, as even the coolest winds/temperatures will damage the delicate leaves.
For a detailed planting calendar, please refer to:
- Seattle Tilth's "The Maritime Northwest Garden Guide" book
- Oregon Tilth planting calendar
- Oregon extension service 's monthly calendar
- Washington State University extension service's information
Garden Tips for May
Enjoy this helpful column by AGC member and garden extraordinaire Kian. Her monthly article is popular with AGC members and others!