Ambler Campus, Temple University

Summer gardens in Philadelphia struggle along from heat wave to heat wave. After a rain, the plants perk up again only to be hit with the next string of 95 degrees plus.

There are always going to be failures, but this year my garden is more colorful than ever. The soil is the key to healthy plants all year long but especially during erratic summer rainfall.

Plan ahead — it is too late to look at a poor, sickly plant now and hope to revive it with a quick drink from a hose. Soil preparation is the key to making your plants drought resilient.

All gardeners chuckle to themselves when they pick up a new plant at the nursery to read the requirements and read “Moist, Well-Drained Soil.” “Ha!” we think — if only we had that soil we could grow anything. But it is true, the nearer that you can get to a good water holding capacity, without water logging the soil, our ordinary garden plants will grow well.

Whether you have a clay or sandy soil, adding good clean compost is the first step. Ideally, compost your own leaves and garden/kitchen waste (no diseased plants, weeds or weed seeds). Next best step, try your local township and see if you can pick up the leaf compost that many of them now make. Third option in the Philadelphia area is the spent mushroom compost from the Kennett Square Mushroom growers — it is good stuff.

Find a way to increase the organic, humus content of your

soil. Compost encourages not only moisture retention but an active soil ecosystem of bacteria, fungi, insects and other soil organisms that break down the bark, leaves, tea leaves, etc. that you have added. That is why you have to keep adding it.Think about the natural Eastern Deciduous forest here in Ambler. Every year the leaves fall, and there is your new mulch and compost.

Speaking of mulch, do add one. Not the type that is piled five inches deep against the sides of the tree, but at least an inch or so, maybe two. Mulch not only keeps moisture in the soil but also suppresses the growth of weeds that compete with your garden plants for moisture. Try the traditional ground bark, or salt hay in a vegetable bed (not straw — too full of weed seeds). My current favorite for dry areas is a gravel mulch. Pick the size and color of gravel or small stones that you like, and put down a couple of inches.

If you have to water, water deeply. Once a week if necessary, and give plants about an inch. If you do not know how much to water, use a rain gauge under the sprinkler. A rain gauge is also a great tool so that you can see how much rain you have had.

So to conclude — what is flowering now in the summer heat. Start with the herbs, many of which are blooming with little extra water. Lavender (Lavandula); tansy (Tanacetum parthenium) a thug but it can be controlled; bronze fennel (Foeniculum vulgare ‘Purpureum’) also aggressive; anise hyssop (Agastache foeniculum) strong aniseed scent; bee balm (Monarda didyma) red, purple, pink or white flowers; cone flower (Echinacea) many new ones out in different shapes, sizes and colors; and yarrow (Achillea) new cultivars such as ‘Paprika’ a lovely red orange, cut back after flowering for some re-bloom.

Other stars in the summer are the tall daisy like flowers, mostly yellow, that everyone confuses with each other. In the garden they fill the same niche at the back of the border. Try my favorite Silphium perfoliatum

or the cup plant or compass plant that grows to 10 to 12 feet tall. The leaves cling around the stem to trap a little water in the ‘cup.’ The goldfinches love this plant and I leave the seed heads on for them. Cup plants are very drought tolerant as they are prairie plants.

Of course the summer phlox (mainly Phlox paniculata) has to be the star of many a herbaceous border at this time of year. In whites and lavenders, this fragrant old-time favorite has many fans and does not need much water.

Finally, if you need a bold splash of red orange, with sword like foliage, the crocosmias are blooming now. The cultivar Crocosmia ‘Lucifer’ is the old favorite that seems to be more hardy than most. It can be grown from a bulb or bought potted up as a plant. There are many other cultivars that I think are slightly less hardy. I am trying Crocosmia ‘Emberglow’ that is bright red in color.

Do come and wander around the arboretum and see what is in bloom. Do not miss the herb garden by Dixon Hall. Pick up one of our new brochures with brief garden descriptions and a map. See you in the garden!