May 2013 Gardening To-Do List: Western Mountains and High Plains

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Winter in the West can be rough on trees, shrubs, and perennials. Drying winds and long hard freezes can do a lot of damage. Though days are warming, nights are still cold, as is the soil. Some plants may be slower to leaf out than others. Don’t be hasty to cut down or remove a plant that looks dead. Give it a couple of extra weeks to green up. Branches that bend are likely still alive. Branches that crack when bent and are brown or tan inside are dead and can be pruned off. Go ahead and prune off broken branches.

 

Annuals

By last frost date, you can plant all your annuals. Late light frosts may harm the tenderest annuals such as impatiens, so keep plastic sheets, burlap bags or bed sheets handy to cover them. Hardy annuals such as geraniums and petunias can tolerate a light frost.

When soil has warmed up and the danger of frost has passed, sow the tender annuals — marigold, nasturtium, and zinnia.

Soak nasturtium and morning glory seeds overnight, then sow.

THD-store-garden-center-hanging-flowers-560x400Perennials

Fertilize spring blooming bulbs early May. Snip the dead flower heads but do not cut back the foliage until it has withered and yellowed.

Thoroughly weed flowerbeds, apply an organic, balanced plant food, and spread a 2-to-3-inch layer of mulch.

Cut back the dead top growth of perennials and perennial grasses. Leave about 3 or 4 inches of stems.

Sow seeds for frost tolerant perennials as soon as the soil has thawed, dried, and begun to warm. Some seeds will not germinate until the soil is quite warm, so check directions on the seed pack.

When planting new perennials, lightly water the soil the day before you plan on planting. You want it moist, but not soggy. Water the plants in their pots a few hours before planting.

Make holes for new plants wide and shallow. Set the root-ball on undisturbed soil so that your plant doesn’t sink as the soil settles, making it susceptible to crown rot. Don’t mix granular fertilizer into the soil at planting time as it can burn tender young roots.

If your tulips are not in the right place, now is a good time to move them. Carefully dig and replant bulbs and their attached foliage in full sun and well-drained soil.

Vegetables

Plant nasturtiums and marigolds all over your vegetable garden to attract pollinators and repel pests.

Don’t rush to plant heat-loving plants like tomatoes, peppers, eggplants, and melons. Wait until the soil is warm and the danger of frost is past. Plants that are exposed to too much cold weather early in their lives may never fully recover. Black plastic mulch laid in the garden bed several weeks before planting will help warm the soil.

Plant seedlings of cool-weather vegetables now, such as broccoli, chard, cabbage and spinach. Plant snow peas directly in the soil. Plant potatoes and carrots now. You can plant root crops and leafy vegetables, such as lettuce and radiccio, either beneath or on the north side of taller vegetables that will protect them from the intense summer sun.

Sow seeds of annual herbs such as dill, chervil, fennel, and cilantro directly in the garden where they are to grow.

Plant green and yellow beans in a sunny location when soil is 60 degrees or warmer. Water well until germination.

Install upright structures such as teepees, trellises, ladders before planting seeds for climbing veggies such as pole beans, cucumbers, vining squashes, and gourds. Stabilize the structure so it doesn’t blow over in a storm. Plant seeds in soil at the base as directed on the seed packet.

Trees/Shrubs

Transplant shrubs and trees after the soil thaws out and dries, while the weather is still cool and before new growth begins.

LilacApply dormant spray to fruit trees before the buds swell and air temperature will be above freezing for at least 24 hours.

Remove any winter protection wraps from your tree trunks to avoid harboring insects.

Apply a liquid or slow release granular fertilizer to spring blooming shrubs after the flowering is complete.

Established azaleas and rhododendrons often do not require additional fertilizer. Test soil for nutrient levels and pH. If the soil is low in nutrients, lightly scatter only a few tablespoons of an acid-forming, granular, slow-release fertilizer on soil under the shrub.

Prune dead lilac flowers as soon as possible after they wilt before brown flower heads go to seed. Prune to shape shrub. Next season’s flowers form early in the lilac branches. So late pruning will remove next spring’s flowers.

Forsythia blooms on the previous year’s wood. Just after the golden yellow flowers die, prune to shape the shrub and fertilize.

Lawn/Turf

Water lawns deep to promote deep roots and develop drought tolerance. The best time to water lawns is early morning. The goal is to apply 1- 3/4 inches of water per week if the weather is dry. Try to stick with native grasses that will need less water and fertilizer to stay healthy.

After the first mowing, apply fertilizer. Include pre-emergent for crabgrass if necessary. Crabgrass seed generally germinates after the soil temperature has reached 50 degrees, and requires about 5 consecutive days of 50-degree soil temperature.

 

 

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