With warm temperatures and summer vegetable and flower gardens getting underway, here are some quick pointers to help you be more successful.
Feed your plants!
Or feed your soil, and let your soil feed your plants.
I’m running into a frequent problem with organic gardeners who make their own compost. They’re doing everything right: saving leaves and garden vegetation and composting it, then spreading it around the garden. Then their plants grow slowly and the older leaves are yellowing: a common sign of nitrogen deficiency.
You need to fertilize your garden for good growth and flowering. A standard rate of application that I find in soil service recommendations and fertilizer handbooks is “1,000 pounds of actual nitrogen per acre.” That’s a useful statistic if you know how to convert your acreage to square feet, and how to read a fertilizer label.
That’s a little more than two pounds of actual nitrogen per 100 square feet; 2.3 to be exact. But do you need exactly 2.3 pounds of fertilizer? No: actual nitrogen. So you need to know what percentage of your fertilizer is actual nitrogen.
A little technical overview here.
Every fertilizer you buy, by law, has two things on the label. The N-P-K formula, and the “guaranteed analysis” telling you how much of each of those is in the bag and what the sources are.
N = nitrogen.
P = phosphorus.
K = potassium.
I am not concerned about P or K. Neither is deficient here.
Here are some examples of guaranteed analyses of N-P-K:
4-6-2 (starter fertilizer, organic)
5-10-10 or 5-5-5 (common synthetic tomato-veg foods)
6-2-1 (cottonseed meal)
13-0-0 (blood meal)
10-1-4 (natural lawn food)
21-0-0 (ammonium sulfate)
That’s a lot of numbers. What should you use?
Manure is popular for gardens because it tends to be inexpensive and readily available. It’s a pretty good source of nitrogen and provides organic matter that makes the soil looser. Manure ranges from 1 to 3 percent nitrogen (steer is lower, chicken is higher). But to provide your nitrogen completely with manure, you’d need (for that 100-square-foot bed) 75 pounds of chicken manure (about four bags) or 230 pounds of steer manure (six to 10 bags).
You can provide 10 to 20 percent of your nitrogen needs by growing a cover crop in the fall and winter. Legumes, which are plants in the bean family, fix nitrogen from the atmosphere in the root zone, helping to feed other plants. A solid bed of fava beans, vetch or clover can reduce the amount of plant food you need to apply. But they won’t provide it all.
Your own homemade compost doesn’t have much nitrogen. It’s a great thing to add to your soil, but not for its plant food value.
Here’s what I do.
I incorporate some all-purpose garden compost to the whole garden bed each year, spreading an inch layer on top and turning it in. What I use contains 15 percent chicken manure. If you’re using your own compost, add some extra manure. That’s four bags (2 cubic foot) per 100 square feet.
I add a small handful of an organic fertilizer that’s 10 percent nitrogen in each planting hole as I put the seedling in. That’s about 10 pounds of fertilizer per 100 square feet.
I grow cover crops, mostly fava beans or vetch, in garden beds in the winter, and I just mow those off in spring and spread the leafy top matter around. That provides about 10 percent of my total nitrogen, and the tops and roots enrich the soil as they decompose.
By my estimates, that all adds up to about two pounds of actual nitrogen. I sometimes feed high-yielding plants like peppers and eggplant again during the summer, simply by sprinkling some more fertilizer alongside them and watering it in. And I plant bush beans in as many little corners as I can because they put nitrogen in the soil as they grow.
Already planted your vegetables or flowers? That’s fine. Just spread some fertilizer around them and carefully cultivate it into the top inch of the soil, then water it in.
Organic or synthetic?
Organic fertilizers are lower-nitrogen, so you need more pounds of them. They are somewhat more expensive than synthetic fertilizers. But there’s a big difference: They release their plant food more slowly and steadily through the season. And the plant food is in the form of organic matter that breaks down and improves the soil structure.
With organic fertilizers, the nitrogen availability is a function of soil temperature, so they tend to be there for the plant when the roots are growing and the plant needs it. Organic fertilizers only need to be applied once a season. And you’re very unlikely to mis-apply them and burn the plant.
Common sources of organic nitrogen, often blended in mixes, include alfalfa meal (very low nitrogen), bat or seabird guano, blood meal, cottonseed meal, feather meal and fish emulsion or meal (great to get seedlings going).
Synthetic fertilizers are higher-nitrogen and cheaper. They are derived from petroleum products. You can feed a garden bed for a few dollars, and you see faster results. But they release all of their nitrogen very quickly, promoting vigorous and sometimes tender new growth.
They’re salts, which can damage roots if applied at rates higher than the label recommendation, and can damage those beneficial soil organisms that help plants feed themselves. They can burn the plant if they aren’t watered in immediately and thoroughly. Within a few weeks they’re gone, so you may need to fertilize again a couple of times during the season.
Common sources of synthetic nitrogen include ammonium phosphate, ammonium sulfate, potassium nitrate and urea.
“Check daily, water as needed.”
Newly transplanted vegetable and flower seedlings may need water every other day for the first few days. Within a week or so, their roots have made a surprising amount of growth, at which point you can water longer and less often. Water thoroughly, deeply and as infrequently as possible. We see a lot of young plants watered more often than needed.
Raised planter beds, and loose, sandy soils drain faster and need more frequent irrigation. They don’t hold nutrients as well, so you may need to apply nitrogen a couple of times during the season. In most other situations, one application would be fine.
The time to plan for the rambunctious growth of your tomato plants is when you plant them. Once they get going they become increasingly difficult to corral into reasonable production units. Most tomatoes are what we call indeterminate, meaning it is a vine that keeps growing all summer and into the fall, often to 10 feet or more.
Those cute little tomato cages sold at most garden stores are no match for a normal tomato in the Sacramento Valley! Make your own cages out of concrete wire that you buy from the lumber store. They need to be at least 6 feet tall and staked securely.
Don’t freak out about the weather
When we get our first day in the 90-degree range, people start to ask “isn’t it getting kind of late to plant?” No!
Soil temperatures for summer vegetables and warm-season flowers are just getting where we want them! I plant peppers and eggplant in May or June and continue planting beans into July. Some of our favorite flowers love heat and loathe cold: verbena, lantana, zinnias are some of the easy stars of the summer garden. Shrubs and trees go in just fine during warm weather so long as you water them properly. Summer is the very best time to plant citrus trees; plants root and grow very quickly in warm soil.
Manage summer pests
Wash off your plants regularly with a strong blast of water. This kills aphids, mites and other insects and removes dust from the leaves. A regular vigorous shower, preferably early in the day, can prevent a lot of pest problems.
Know the good guys! Beneficial insects are hard at work in your garden. Summer gardens rarely need any pesticides.
Smother summer weeds. Weeds that sprout in May grow very fast and take over by August. Good-quality landscape fabric can minimize weed problems and help conserve soil moisture.
Plant some flowers
Or, plant some edibles among your flowers. Certain flowers draw beneficial insects into your garden. Cosmos and marigolds draw butterflies, borage draws bees, sweet alyssum attracts beneficial predatory insects. Diversity is always good in the garden.
— Don Shor and his family have owned the Redwood Barn Nursery since 1981. He can be reached at [email protected]. Archived articles are available on The Enterprise website, and they are always available (all the way back to 1999) on the business website, www.redwoodbarn.com