Vegetables can be classified based on the family or genus to which they belong – this gives us information about how to use and care for them. For example, plants from the genus Brassica are called cole crops, and they are generally cool-season crops – they grow best at cooler temperatures. Cucurbits come from the family Cucurbitaceae (the gourd family) – they grow best at warmer temperatures. Vegetables are also classified based on the plant part that is eaten – roots, leaves, or fruits. This is important during planting and care. Remember that high-nitrogen fertilizers produce vegetative growth – they work well with vegetables produced for their leaves but not so well on root vegetables. Roots vegetables should treated with a lower nitrogen fertilizer. On the other hand, both root and leafy vegetables do just fine in semi-shady areas of your yard, whereas fruit-bearing vegetables such as tomato or pepper require full sun to get enough photosynthate to produce flowers and fruit.
One of the most important classifications of vegetables is whether they are considered warm- or cool-season. This information tells you when is the best time for planting to get the most out of your vegetable harvest. Cool-season vegetables prefer daytime temperatures of about 60 to 64 deg, and many will tolerate a light frost – they can be planted early in spring as soon the soil can be worked. This includes popular vegetables like spinach, broccoli, and radishes. Other cool-season vegetables should be planted about 2 weeks later in spring than the first group because they will be damaged by temperatures close to freezing – many leafy vegetables fit in this category as do carrots. Cool-season vegetables should not be planted too late in the season, because heat will produce a poorer quality product. Some cool-season vegetables will “bolt” in warmer weather. Bolting is flowering that occurs as a response to the shorter nights and warmer days of late spring and summer. Warm-season vegetables must be planted after danger of frost has passed – they are frost-tender. And they will grow slowly and may fail to develop fruit at temperatures lower than 55-65 deg.
The number of days from the last spring frost until the until the earliest fall frost is called the frost-free period. The frost-free period varies with latitude and ranges from 60 days in North Dakota to 250 days in the southern part of the U.S. This is an important concept to consider when deciding on vegetable cultivars to grow. The days to maturity is listed on vegetable seed packets and provided with transplants – it tells you how long from seed or transplant to time of harvest is required for the vegetable. Obviously, people living in cold-winter climates will be more limited in their vegetable cultivar selection because of their relatively shorter growing season. Good cultivars for your region can be found on the Cooperative Extension web site – your local garden center may also recommend appropriate varieties. The map on this slide tells you the date of last frost for your area if you live in the U.S. By finding where you live on the map, you can find out how early you can grow frost-tender vegetables and plan your garden accordingly. Other freeze/frost maps can be found at the web site listed at the bottom of the slide.
As mentioned previously, different vegetables have different tolerances for heat and cold. By using the map on the previous slide to find your frost-free date, knowledge of the frost-free period for your region, and information on the temperature tolerances of the vegetables you’d like to grow, you should be able to plan your garden. Information on this slide is specific to areas along the Wasatch Front in Utah, but similar information can be found at your local Cooperative Extension office. It is important that the first planting of your vegetables be as early in the spring as possible without danger of cold damage to the vegetable – that way you can be assured of a good harvest before the first fall frost.
Choosing a site for your garden is an important decision because it will ultimately determine how successful you will be. A good site will have plenty of sunshine and will be far enough away from trees to avoid shading at certain times of the day and so that vegetable roots don’t have to compete with tree roots for water and nutrients. Any rich, loamy soil will do as long as it is well draining. Gardens can be planted in clayey or sandy soils, but some preparation will need to be done ahead of time to improve its structure. Also consider where your water supply is, so that you will be able to irrigate when needed. The garden should not be located on a steep slope where water will run off rapidly – water that runs off is not available for plant growth and can lead to erosion of soil. If the garden must be planted on a gentle slope, plant in rows along or around the hill rather than up and down in order to allow water to drain into the soil.
Now that you have your garden in, you will need to watch and protect from damage by insect pests. Control of pests will be discussed at greater length in Unit 4, but there are some easy and safe strategies for reducing pest attacks. For example, aphids are known to be repelled by garlic, and radishes repel beetles that attack tomatoes, squash, and eggplant. Radishes also repel mites. Other natural repellents are listed on this slide – these plants can be planted in your garden and also used for food or for ornamental purposes.
A garden plan saves time and work and doesn’t have to be complicated. A simple drawing will do. On graph paper, draw a sketch of the area to be planted – preferably to scale. Remember that a small well kept garden gives better returns than a large weedy one. Try to avoid having taller plants shading out shorter ones – this can be done by planting rows in an east-west direction. Block gardens can also be used to get maximum yield from minimum space – a block garden is pictured on this slide. Larger gardens should have paths planned in for easy access for cultivation and harvest. Separate crops that will remain in the ground for multiple years – perennial crops – from annual crops to avoid disturbing perennial plant root systems. Succession cropping – planting at intervals of every two weeks – can provide an almost continuous harvest throughout the season. Most crops can be succession cropped, with the exception of slow-to-mature warm-season vegetables.
Seeds are usually planted in rows or hills. Mark each row with a labeled stake and form a shallow row with a hoe handle, using a string stretched the length of the row to keep it straight. Follow directions on the seed packet for appropriate planting depth and spacing. Don’t worry about planting too many seeds as some will not germinate and you will be thinning them after they germinate. A common practice is to interplant fast-germinating seeds such as radish with slow-germinating seeds such as carrots. The radishes will germinate in a few days and mark the row for you. They will be harvested in three weeks – well before the carrots start to develop. Make sure to water seeds in after planting and keep the soil moist until they germinate. Seeded plants will need to be thinned as soon as leaves of neighboring plants touch. Thinning allows you to choose the most vigorous plants and provides proper spacing between plants. Plants that are purchased or grown indoors for outdoor transplanting should be installed in the garden during the cooler part of the day – before 10 a.m. or in early evening. Vegetable transplants should be planted slightly deeper than they were in their pots. Tomatoes should be planted with a good portion of its stem in the ground to encourage adventitious root development along the submerged stem. Remember to harden off plants you have planted indoors from seed before bringing them outdoors. This involves gradually lowering the temperature and humidity and increasing light levels to which they have been exposed as seedlings.
Heidi Kratsch,University of Nevada Cooperative Extension
Cool-season vegetables – prefer daytime temperatures 15-18°C (60-65°F) ◦ Spinach, cabbage, broccoli, radish, beet, asparagus, garlic, brussels sprouts (frost tolerant) ◦ Lettuce, celery, artichoke, endive, mustard, carrot (damaged by temps near freezing) Warm-season vegetables – must be planted after danger of frost has passed ◦ Sweet corn, pepper, snap beans, squash, pumpkin, lima beans, cucumber, tomato, cantaloupe
Frost free period ◦ Calculated from date of last spring frost to date of first fall frost Days to maturity ◦ Seed to harvest ◦ Differs by cultivar Frost-tolerance
Cultivar = cultivated variety Examples: ◦ „Early Girl‟ tomatoes ◦ „Sugar Ann‟ snap peas ◦ „Buttercrunch‟ lettuce ◦ „Royal burgundy‟ bush beans Cultivars are varieties within a crop selected for a particular characteristic.
EARLY SPRING LATE SPRING/EARLY Late SUMMER summerHARDY SEMI-HARDY TENDER VERY TENDER HARDYAsparagus Beet Celery Cantaloupe BeetsBroccoli Carrot Cucumber Eggplant CabbageBrussels Cauliflower Dry bean Lima bean Kalesprouts Endive Snap bean Pepper LettuceCabbage Lettuce New Zealand Pumpkin OnionKale Parsley spinach Tomato RadishOnions Parsnip Sweet corn Watermelon RutabagaPeas Potato Zucchini Winter SpinachRadish Salsify squash TurnipRhubarb Swiss chardSpinachTurnip
Sunlight – avoid trees Good soil – sandy loam is best Source of water Avoid steep slopes Protection from strong wind
South, east, west exposure Afternoon shade will protect sensitive fruits in a western exposure. Eastern exposure – sunlight less intense (6 hours minimum)
Must be accessible Hose dragging can pull up or damage plants. May need more than one water source.
Ideal is 50% permeable. Should be as long as possible. Windbreaks meeting at right angles give maximum protection against shifting winds.
Three-season gardening Relaying: overlapping planting of one crop Planting several varieties of the same crop
Early Spring (March 15): cool season veggies Summer – late May / early June: warm season veggies Fall – August: cool season veggies (again)
Allows dense plantings. Avoids competition for nutrients and light. Simple schemes: ◦ Onions, lettuce, carrots ◦ Radishes, lettuce, pepp ers ◦ Brussels sprouts, parsley, spinac h, onions
Three Sisters Method: Relies on complementary characteristics: ◦ Corn is a heavy feeder but provides a trellis for ◦ Beans, which fix N for corn and ◦ Squash, which shades the ground
Plant polycultures. Interplant herbs and flowers. Provide refuge for beneficial insects. Use least toxic methods to control pests. Know your weeds. Cleome serrulata
Plant: Repels: Basil Flies/mosquitoes Marigold Many insects Garlic Many pests Mint Cabbage moths Onion Ants Radish Many insects Rosemary Bean beetles Tansy BeetlesSource: Horticulture Principles and Practices, 4th ed., G. Acquaah, Pearson Education, NJ
A example of a 4-foot by 8-foot raised bed design
From seed indoors: ◦ Sterile “soil” – fine ◦ Plant 2-3x the width of the seed. ◦ Label! ◦ Use mist to water ◦ Cover until they begin to germinate. ◦ Artificial vs. natural Seedlings in egg carton light ◦ Heat: 60-75 deg F