Harvesting the first crop from your vegetable garden is a very satisfying experience. The sense of accomplishment is even greater when you have overcome the challenges presented with gardening at high altitude. Cold nights with unseasonable frosts and a short growing season are to be expected when growing vegetables at elevations of 4,900 feet or more. However, with extra preparation and season-extending techniques, vegetable gardening in the high country can be very rewarding.
Select a garden location that gets at least eight hours of full sun each day. Vegetables love sunshine, so the more the better. If your land slopes, choose a southern exposure that will increase both light and heat. Raised beds are an effective way to increase soil warmth and light for northern exposures. You will also need access to a water supply for your garden.
Completely remove all plants and debris form a small plot. Even a garden of 200 square feet can produce a good harvest; it can be expanded as you gain experience. Loosen the top 6 inches of soil and spread 4 to 6 inches of well-aged compost or manure over the area. Dig the organics in lightly and allow them to break down for about a week before planting.
Make a drawing of your garden and plan the layout indicating the rows and what will be planted. Tomatoes and other warm season vegetables are challenging at high altitudes due to the short growing season. They must be started indoors six to eight weeks before the last frost to have a chance of success. Cold hardy crops like onion, lettuce, peas, cabbage and most root vegetables are better choices for new gardeners. Contact local nurseries or gardening groups for advice on what to plant in your area.
Level out the plot with the rake and mark your rows using wooden stakes and string. Pull the soil into a mound 8 to 10 inches high along each row. This will keep the soil warmer and make weeding easier. Carefully follow the directions for spacing and depth when planting the seeds.
Dig in the compost or manure to mix it well with the soil. Rake the plot level. Using your drawing as a guide, place stakes at the ends of the rows and tie string between them. Make a mound of soil about 6 inches high along the length of each row. Read the directions on each seed package and sow according to the depth and spacing instructions. Plant cold-hardy vegetables such as onions, peas, lettuce and spinach first. In Denver at an elevation of 5,280 feet, most gardeners plant these crops by the end of March or first week of April.
Give your garden at least 1 inch of water per week. This can be reduced if there is adequate rainfall. Watering should be done early in the day; it is best to give the soil one good weekly soaking rather than a light spray each day. Remove weeds as soon as possible and check your plants for any signs of insects or disease as they grow. Consult a local nursery or garden center for advice if you notice any problems of this sort.