Garden Notes

Iceland poppies: Photo by Susan Safford
Iceland poppies fill a planter on Main Street in Vineyard Haven. Photo by Susan Safford

New season, new responsibilities

By Abigail Higgins - June 22, 2006

Welcome to summer, the solstice having occurred yesterday. With the change of season comes the need to monitor containers, which, until now, have been mostly self-tending due to the cool, wet, and overcast conditions. With the arrival of summer and more settled and warm weather, container plantings will surge in growth and consequently suffer from dryness quite suddenly.

Depending upon the potting mix you use in your container and the number of plants it contains, it will be necessary to water at most every day to at least twice a week. The exception to this is if you are using some of the containers that have built-in internal reservoirs and wicking systems. In that case it is necessary to fill the reservoirs often enough to keep up with the plants' demands. Although my experience with gel-products added to potting mix to hold more water is limited, I do not like them and do not use them. It is better to get the potting mix right for your needs.

Despite the expense, containers look good when they are planted generously: "stuffed." But they skate closer to disaster's edge - drought - with all those plants transpiring all that moisture all the time the sun is shining. Be sure to choose a container of volume equal to the job of supporting the material it contains. Then too, potting soil varies considerably.

Potting mixes formulated with peat moss and vermiculite or perlite will usually be faster draining and will therefore need to be watered more frequently. On the other hand, a potting mix that is moisture retentive can promote algae formation or root rot. A generous layer of material that promotes drainage in the container's bottom will help. Broken terracotta pieces are traditional, laid over the drainage hole; but Styrofoam peanuts, the bane of mail order shopping, are put to good use as a drainage layer in the bottom of containers and have the added advantage of light weight. Place a moistened section of newspaper or paper towel between the layer of peanuts and the potting mix if you are concerned about soil washing through and out onto your patio or deck.

I often use a four-inch plastic pot, of which I generate untold hundreds from work, upturned and placed over the drainage hole. Although most gardeners appreciate the convenience of bagged potting soils, the mix can be homemade, which is what gardeners of yesteryear did perforce. Google "John Innes composts" for a wealth of information on doing this yourself.

Once the containers have been planted up and are growing nicely, you will need to keep them that way. Soluble fertilizers and time-release fertilizer pellets such as Osmocote are two ways to feed containers. Make a point of checking the NPK (nitrogen - phosphorus - potassium) numbers on the product, as there are several different formulations. Many of the tender perennials available that work so well in containers need a feed high in nitrogen and much lower in phosphorus, in order to thrive and last all season. Check pot tags for cultural tips. Be sure to deadhead and pinch the plants frequently.

There are so many tasks that need doing simultaneously in June! Caterpillar patrol or spraying alone can take up most of the time that busy people have available for plant and garden care. (I am sick of them - the caterpillars, that is.) I recommend a spreader/sticker product to make whatever you are spraying adhere. Turbo and Nu Film are two such products. My roses have been hard punished by sawfly larvae (skeletonized leaves and green worms) this year, and I have been too busy elsewhere to take proper action; I have a large population of sawflies at my place for some reason. As they are not true caterpillars, they must be treated with insecticidal soap or rotenone spray. Side dress with rose food or fertilizer every month to keep the flowers coming.

I have received several queries about lily leaf beetles, which are active now in both adult and larval form. The larvae are the really destructive aspect of Lilioceris lilii, but are not too difficult to control by scraping them off the undersides of the lily's leaves. The larvae envelop themselves in their own excrement, which seems to put some people off, not too surprisingly, but, especially wearing gloves or using a throwaway plastic knife, scraping them off is something we can steel ourselves to do. Dispose of them in a jar of water and dish detergent. Hunt down the bright red adults in morning or late in the day when they are sluggish. I pinch off their heads with my fingernail.

Rhododendron bushes will benefit from deadheading, both aesthetically and for the new growth they are forming. (Obviously this is impractical if they are enormous old plants.) This is the time to prune them, and also azaleas, in order to keep them within bounds in foundation plantings.

Deadheading in the garden starts now in earnest as peony and iris go by. Siberian iris in particular are prolific self-seeders and love to migrate to new homes where they can be difficult to remove if they become established, for instance in pea stone walks and parking areas. Cut down the stems that flowered while the seedpods are still green and closed. Staking time is here too.

When there are free moments, pinching out the growing tips of annuals and some perennials will result in bushier growth that needs less staking, more flowers, and slightly later bloom. (I often do this or plucking crabgrass while taking phone calls.) Many gardeners are familiar with this pinching practice in regard to garden mums, but it can also be done with many other flowers, especially phlox, asters, salvias, zinnias, dahlias, and cosmos.

In vegetable gardens the timetables are more variable due to the degrees of diligence of individual gardeners; in general though it will be time to make more succession sowings of greens, beans, carrots and beets. Side dress the tomatoes and cucurbits and other heavy feeders. Keep onions well weeded.

Weed control now is paramount and will save much time and effort later on. My preferences for cultivator tools for row crops are the push-pull (stirrup) hoe, long-handled tined cultivator, and of course a wheel hoe. In smaller vegetable patches hand tools are all one needs: a cultivator claw and a Cape Cod weeder. Soils that are tough to weed are those that are most likely in need of improvement; so add as much organic matter as possible.